Effect of weight loss and regain on adipose tissue distribution, composition of lean mass and resting energy expenditure in young overweight and obese adults

Increasing the health span: unique role for exercise

Health span, that period between birth and onset of major disease(s), when adequate physical and cognitive function permit those daily living activities essential to life quality, is lower in the United States than other developed countries. Physical inactivity and excessive calorie intake occupy dominant roles both in the problem, and by redressing them, in the solution. Consequently, this review focuses on evidence that appropriate exercise engagement and calorie restriction (CR) can improve physical and mental health with a view to extending the health span. Humanity, writ large, has grasped these underlying concepts for Millennia but has been largely intransigent to them. Thus, the final section proposes a novel Monty Python-esque approach that encompasses humanity's inimical sense of humor to increase physical fitness and mental health, restore energy balance, sustain better cognitive function, and extend the health span.

Adaptive thermogenesis driving catch-up fat during weight regain: a role for skeletal muscle hypothyroidism and a risk for sarcopenic obesity

Across the spectrum of weight regain, ranging from cachexia rehabilitation and catch-up growth to obesity relapse, the recovery rate of body fat is often disproportionate relative to lean tissue recovery. Such preferential 'catch-up fat' is in part attributed to an increase in metabolic efficiency and embodied in the concept that 'metabolic adaptation' or 'adaptive thermogenesis' in response to large weight deficits can persist during weight regain to accelerate fat stores recovery. This paper reviews the evidence in humans for the existence of this thrifty metabolism driving catch-up fat within the framework of a feedback loop between fat stores depletion and suppressed thermogenesis. The search for its effector mechanisms suggests that whereas adaptive thermogenesis during weight loss results primarily from central suppression of sympathetic nervous system and hypothalamic-pituitary-thyroid axis, its persistence during weight regain for accelerating fat recovery is primarily mediated through peripheral tissue resistance to the actions of this systemic neurohormonal network. Emerging evidence linking it to an upregulation of skeletal muscle type 3 deiodinase (D3), the main thyroid hormone inactivating enzyme, along with slowed muscle metabolism and altered contractile properties, suggest that D3-induced muscle hypothyroidism is a key feature of such peripheral resistance. These findings underlying a role of skeletal muscle hypothyroidism in adaptive thermogenesis driving catch-up fat, but which can also concomitantly compromise muscle functionality, have been integrated into a mechanistic framework to explain how weight cycling and large weight fluctuations across the lifespan can predispose to sarcopenic obesity.

Weight cycling and its effects on muscle mass, sarcopenia and sarcopenic obesity

The prevalence of obesity is rising around the world, as the number of subjects dieting and experiencing weight loss followed by unintentional weight regain, the so-called weight cycling (WC). In this narrative review we sought to reveal the effects of WC on body composition as well as to evaluate if WC may represent a risk factor for sarcopenia and sarcopenic obesity. The relative changes in lean and fat compartments after WC have been shown to depend on several factors as the degree of energy deficit, the rate of weight loss and baseline body weight, as well as sex, age, physical activity and subject's metabolic or hormonal status. Effects of WC on body compartments may be underestimated depending on body composition measurements, interference of physical exercise, number of WC, age and population characteristics. Studies using the most precise methods to assess body composition changes, as well those with higher number of WC and/or including old subjects, show that with WC, lower fat free mass (FFM) is regained with a mismatch between muscle and fat. In addition, when WC is involuntary in old age, it drives and accelerates the age-related loss of FFM, in particular in frail populations. Finally, an association between WC and sarcopenia or sarcopenia obesity, was also observed when evaluating strength together with WC-related body composition changes. In conclusion WC may act as an accelerator of biological aging, and it could be further investigated as a potential risk factor for sarcopenia or sarcopenic obesity.

Changes in Trunk, but Not Limb, Lean Body Mass Contribute to Variability in Metabolic Adaptation Following Weight Loss

Background

Metabolic adaptation (MA) in response to weight loss is highly variable. Several methodological issues are likely to contribute to the large inter-individual variability in MA, namely the lack of adjustment for changes in the composition of fat-free mass.

Objective

The aim of this analysis was to investigate the contribution of changes in trunk versus limb lean body mass (LBM) to the variability in MA, at the level of resting metabolic rate (RMR).

Methods

116 premenopausal women with overweight (body mass index (BMI): 28.2 ± 1.2 kg/m2; age: 34.4 ± 6.4 years) enrolled in a weight loss program. Body weight/composition (dual energy x-ray absorptiometry), RMR (indirect calorimetry) and insulin sensitivity (SI) (intravenous glucose tolerance test) were measured after 4 weeks of weight stability at baseline and after weight loss. Multiple linear regression was used to determine the contribution of changes in trunk versus limb LBM to MA variability, after adjusting for relevant confounders.

Results

A large variation in MA (-206 to +233 kcal/day) was found after an average of 12.1 ± 2.4 kg weight loss. After adjusting for RMR at baseline and changes in SI, changes in trunk (but not limb) LBM were a significant contributor to MA variability.

Conclusion

In premenopausal women with overweight and loss of trunk, but not limbs, LBM contributes to MA variability, suggesting that loss of organ mass might be more important than loss of skeletal mass in modulating the magnitude of MA. Trial Registration: ClinicalTrial.gov Identifier (JULIET study): NCT00067873, URL: https://clinicaltrials.gov/ct2/show/NCT0006787.

Long-Term Yo-Yo Dieting Exaggerates Liver Steatosis and Lesions but Preserves Muscle Performance in Male Zebrafish

Weight regain within one year after weight loss is frequently observed and is referred to as yo-yo dieting or weight cycling. In this study, we explore the effects of yo-yo dieting on the liver, adipose tissue, and muscle characteristics of male zebrafish. Four-month-old AB wild-type male zebrafish were randomly assigned to three groups: high-calorie intake (H, seven meals per day), low-calorie intake (L, two meals per day), and yo-yo diet (the low- and high-calorie alternation switched every two weeks) groups. Feeding the fish the H diet for over 8 weeks led to steatosis and damage to the liver. The yo-yo diet reduced liver lipid accumulation at week eight but caused a similar degree of lipid accumulation as the H diet thereafter. It was found that twenty weeks of yo-yo dieting actually exacerbated hepatic damage. Compared to the L diet, feeding the fish on the yo-yo and H diets for a period of 20 weeks significantly increased the size of muscle fibers, resulting in higher speed during burst swimming and a significant increase in the size and number of adipocytes in the abdominal tissue. To summarize, short-term yo-yo dieting was found to attenuate hepatosteatosis and maintain fast-twitch muscle function. Long-term yo-yo dieting preserved fast-twitch muscle function and muscle fiber size; however, it exacerbated the pathological changes in the liver.

Effects of multidisciplinary therapy on energy balance, inflammation, and metabolic diseases in adolescents with obesity: A narrative review

Obesity is a consequence of multiple factors, including genetics, lifestyle and nutritional choices, physical activity, sleep duration, screen time, and mood disorders. These behavioral elements can impair the regulation of energy balance and obesity management that link obesity to a constellation of chronic conditions that lead to a high prevalence of cardiometabolic risk factors, metabolic syndrome, and nonalcoholic fatty liver disease. Multidisciplinary therapy is defined as an approach delivered by a multidisciplinary-trained health team covering at least two components of behavior, physical activity/exercise, dietary habits, and/or psychological counseling associated with clinical interventions. This narrative review summarizes the effects of multidisciplinary therapy on neuroendocrine regulation of energy balance, inflammatory biomarkers, cardiometabolic risk factors, metabolic syndrome, nonalcoholic fatty liver diseases, behavior, and quality of life. We found that multidisciplinary therapy, including medical, nutritional, exercise, and behavioral counseling, and/or education, was useful for addressing outcomes such as visceral adiposity, neuroendocrine regulation of energy balance, inflammatory biomarkers, cardiometabolic risk factors, nonalcoholic fatty liver disease, and metabolic syndrome. The effects were mediated by improvements in neuroendocrine regulation of energy balance, downregulation of the pro-inflammatory states, and a reduction in comorbidities. Multidisciplinary therapy also improved mood disorders and quality of life.

Impact of baseline adipose tissue characteristics on change in adipose tissue volume during a low calorie diet in people with obesity-results from the LION study

BACKGROUND/OBJECTIVES

Weight loss outcomes vary individually. Magnetic resonance imaging (MRI)-based evaluation of adipose tissue (AT) might help to identify AT characteristics that predict AT loss. This study aimed to assess the impact of an 8-week low-calorie diet (LCD) on different AT depots and to identify predictors of short-term AT loss using MRI in adults with obesity.

METHODS

Eighty-one adults with obesity (mean BMI 34.08 ± 2.75 kg/m², mean age 46.3 ± 10.97 years, 49 females) prospectively underwent baseline MRI (liver dome to femoral head) and anthropometric measurements (BMI, waist-to-hip-ratio, body fat), followed by a post-LCD-examination. Visceral and subcutaneous AT (VAT and SAT) volumes and AT fat fraction were extracted from the MRI data. Apparent lipid volumes based on MRI were calculated as approximation for the lipid contained in the AT. SAT and VAT volumes were subdivided into equidistant thirds along the craniocaudal axis and normalized by length of the segmentation. T-tests compared baseline and follow-up measurements and sex differences. Effect sizes on subdivided AT volumes were compared. Spearman Rank correlation explored associations between baseline parameters and AT loss. Multiple regression analysis identified baseline predictors for AT loss.

RESULTS

Following the LCD, participants exhibited significant weight loss (11.61 ± 3.07 kg, p < 0.01) and reductions in all MRI-based AT parameters (p < 0.01). Absolute SAT loss exceeded VAT loss, while relative apparent lipid loss was higher in VAT (both p < 0.01). The lower abdominopelvic third showed the most significant SAT and VAT reduction. The predictor of most AT and apparent lipid losses was the normalized baseline SAT volume in the lower abdominopelvic third, with smaller volumes favoring greater AT loss (p < 0.01 for SAT and VAT loss and SAT apparent lipid volume loss).

CONCLUSIONS

The LCD primarily reduces lower abdominopelvic SAT and VAT. Furthermore, lower abdominopelvic SAT volume was detected as a potential predictor for short-term AT loss in persons with obesity.

Gut-muscle communication links FGF19 levels to the loss of lean muscle mass following rapid weight loss

OBJECTIVE

Optimal weight loss involves decreasing adipose tissue while preserving lean muscle mass. Identifying molecular mediators that preserve lean muscle mass is therefore a clinically important goal. We have shown that circulating, postprandial FGF19 levels are lower in patients with obesity and decrease further with comorbidities such as type 2 diabetes and MASLD. Preclinical studies have shown that FGF15 (mouse ortholog of human FGF19) is necessary to protect against lean muscle mass loss following metabolic surgery-induced weight loss in a mouse model of diet-induced obesity. We evaluated if non-surgical weight loss interventions also lead to increased systemic levels of FGF19 and whether FGF19 levels are predictive of lean muscle mass following rapid weight loss in human subjects with obesity.

RESEARCH DESIGN AND METHODS

Weight loss was induced in 176 subjects with obesity via a very low-energy diet, VLED (800 kcal/d) in the form of total liquid meal replacement for 3-4 months. We measured plasma FGF19 levels at baseline and following VLED-induced weight loss. Multiple linear regression was performed to assess if FGF19 levels were predictive of lean mass at baseline (obesity) and following VLED.

RESULTS

Postprandial levels of FGF19 increased significantly following VLED-weight loss. Multiple linear regression analysis showed that baseline (obesity) FGF19 levels, but not post VLED FGF19 levels, significantly predicted the percent of lean muscle mass after VLED-induced weight loss, while controlling for age, sex, and the baseline percent lean mass.

CONCLUSION

These data identify gut-muscle communication and FGF19 as a potentially important mediator of the preservation of lean muscle mass during rapid weight loss.

Effects of Additional Protein Intake on Lean Body Mass in Patients Undergoing Multimodal Treatment for Morbid Obesity

(1) Multimodal treatment is a standard treatment for patients with obesity. However, weight loss also leads to reductions in fat-free mass. The aim was to investigate whether additional protein intake contributes to better preservation of lean body mass (LBM). (2) A total of 267 obesity patients (age 45.8 years; BMI 47.3 kg/m2) were included in this analysis. For the first 12 weeks of the program, patients were given a formula-based diet of 800-1000 kcal per day. Patients were divided into a control group (CG) (n = 148) and a protein group (PG) (n = 119). The PG was characterized by an additional protein intake with the aim of consuming 1.5 g of protein per kilogram of normalized body weight, whereas the CG had a protein intake of 1 g/kg/d. Bioelectrical impedance analysis was performed at the beginning (t0) and after 12 weeks (t1) of the program. (3) There were no significant differences between the groups with respect to weight loss (p = 0.571). LBM was also significantly reduced in both groups, without significant differences between CG and PG. (4) Increased protein intake had no significant effect on body composition of morbidly obese patients during a 12-week formula-based diet and multimodal treatment.

The Physiological Effects of Weight-Cycling: A Review of Current Evidence

PURPOSE OF REVIEW

There is a common perception among the public that yo-yo dieting, defined as repeated cycles of weight loss followed by weight regain, results in accumulation of fat in the body and lower metabolic rate, thus hindering subsequent attempts to lose weight. We evaluated the effects of weight-cycling on body weight and body mass index (BMI), body composition including fat mass (FM) and lean body mass (LBM), and resting metabolic rate (RMR), by systematically reviewing existing scientific literature.

RECENT FINDINGS

Twenty-three cross-sectional and cohort studies (including subjects with a history of weight-cycling compared to those without such history) and interventional studies (evaluating physiological effects during one or more cycles of weight loss and regain) were identified, conducted in generally healthy adults across various age groups, races, and both genders, who had normal weight, overweight, or obesity. Eighteen studies investigated the association between weight-cycling and body weight or BMI, and thirteen of them found no significant association. Fifteen out of twenty studies also found no increase in FM, and none of eighteen studies found a decrease in LBM. Twelve out of fourteen studies reported no adverse changes in RMR either. The overwhelming majority of evidence suggests that weight-cycling (yo-yo effect) is not associated with any adverse effects in body weight, body composition, and metabolic rate. Accordingly, healthy individuals who struggle with overweight or obesity should not be discouraged from repeated attempts to lose the excess weight.

Proportion of caloric restriction-induced weight loss as skeletal muscle

OBJECTIVE

This study's objective was to develop models predicting the relative reduction in skeletal muscle (SM) mass during periods of voluntary calorie restriction (CR) and to validate model predictions in longitudinally monitored samples.

METHODS

The model development group included healthy nonexercising adults (n = 897) who had whole-body SM mass measured with magnetic resonance imaging. Model predictions of relative SM changes with CR were evaluated in two longitudinal studies, one 12 to 14 weeks in duration (n = 74) and the other 12 months in duration (n = 26).

RESULTS

A series of SM prediction models were developed in a sample of 415 males and 482 females. Model-predicted changes in SM mass relative to changes in body weight (i.e., ΔSM/Δbody weight) with a representative model were (mean ± SE) 0.26 ± 0.013 in males and 0.14 ± 0.007 in females (sex difference, p < 0.001). The actual mean proportions of weight loss as SM in the longitudinal studies were 0.23 ± 0.02/0.20 ± 0.06 in males and 0.10 ± 0.02/0.17 ± 0.03 in females, similar to model-predicted values.

CONCLUSIONS

Nonelderly males and females with overweight and obesity experience respective reductions in SM mass with voluntary CR in the absence of a structured exercise program of about 2 to 2.5 kg and 1 to 1.5 kg per 10-kg weight loss, respectively. These estimates are predicted to be influenced by interactions between age and body mass index in males, a hypothesis that needs future testing.

The BREAK study protocol: Effects of intermittent energy restriction on adaptive thermogenesis during weight loss and its maintenance

BACKGROUND

Adaptive thermogenesis, defined as the decrease in the energy expenditure components beyond what can be predicted by changes in body mass stores, has been studied as a possible barrier to weight loss and weight maintenance. Intermittent energy restriction (IER), using energy balance refeeds, has been pointed out as a viable strategy to reduce adaptive thermogenesis and improve weight loss efficiency (greater weight loss per unit of energy deficit), as an alternative to a continuous energy restriction (CER). Following a randomized clinical trial design, the BREAK Study aims to compare the effects of IER versus CER on body composition and in adaptive thermogenesis, and understand whether participants will successfully maintain their weight loss after 12 months.

METHODS

Seventy-four women with obesity and inactive (20-45 y) will be randomized to 16 weeks of CER or IER (8x2 weeks of energy restriction interspersed with 7x1 week in energy balance). Both groups will start with 2 weeks in energy balance before energy restriction, followed by 16 weeks in energy restriction, then 8 weeks in energy balance and finally a 12-month weight maintenance phase. Primary outcomes are changes in fat-mass and adaptive thermogenesis after weight loss and weight maintenance. Secondary outcomes include weight loss, fat-free mass preservation, alterations in energy expenditure components, and changes in hormones (thyroid function, insulin, leptin, and cortisol).

DISCUSSION

We anticipate that The BREAK Study will allow us to better understand adaptive thermogenesis during weight loss and weight maintenance, in women with obesity. These findings will enable evidence-based decisions for obesity treatment.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT05184361.

HIGH-FIBER DIET PROMOTES METABOLIC, HORMONAL, AND SATIETY EFFECTS IN OBESE WOMEN ON A SHORT-TERM CALORIC RESTRICTION

•Body weight and BMI decrease in both the EG and CG groups during the period of caloric restriction. •For both the EG and CG groups, fat-free mass decreases during food restriction. •Subjects on a high-fiber diet have reduced fasting glucose and basal insulin as well as improved insulin resistance, as attested by the lower HOMA-IR index. •Obese women on a high-fiber diet have suppressed postprandial (after 60 min) acylated ghrelin, confirming that the diet composition influences ghrelin levels from the first day. •In the present study, it was possible to verify that fasting leptin concentration diminishes in obese women on a high-fiber diet. Background - Several mechanisms, including excessive hunger, account for patients' difficulties in maintaining weight loss and dietary changes after caloric restriction. Objective - To evaluate the effect of short-term high-fiber calorie-restricted diet in appetite-regulating hormones, and hunger and satiety sensations in women with obesity. In a randomized controlled trial study, thirty women with body mass index (BMI) higher than 30 kg/m2, and aged from 20 to 50 years were hospitalized following a calorie-restricted diet (1000 kcal/day) for three days. The experimental group (n=15) received high-fiber diet and the control group (n=15), conventional diet. Results - Body weight, BMI, resting energy expenditure (REE), acylated and total ghrelin, leptin, insulin and glucose, and hunger and satiety sensations were evaluated. Linear regression models with mixed effects (fixed and random effects) helped to assess the variables between the two groups and within the groups. Body weight and BMI decreased in both the experimental and control groups (P<0.001). After the high-fiber diet, postprandial acylated ghrelin (P=0.04), glucose (P<0.001), insulin (P=0.04), and leptin (P=0.03) levels as well as the HOMA-IR index (P=0.01) decreased, whereas satiety improved (P=0.02). Obese women that followed the conventional diet had increased body fat percentage (P=0.04) and lower REE (P=0.02). The two diets did not differ in terms of hunger sensation. Conclusion - A short-term high-fiber diet improves satiety sensations and metabolic parameters while suppressing postprandial acylated ghrelin (60 minutes) and maintaining the resting energy expenditure.

Weight cycling based on altered immune microenvironment as a result of metaflammation

As a result of the obesity epidemic, more people are concerned about losing weight; however, weight regain is common, leading to repeated weight loss and weight cycling. The health benefits of early weight loss are nullified by weight regain after weight cycling, which has much more severe metabolic consequences. Weight cycling alters body composition, resulting in faster fat recovery and slower muscle reconstruction. This evident fat accumulation, muscle loss, and ectopic fat deposition destroy the intestinal barrier, increase the permeability of the small intestinal epithelium, and cause the lipotoxicity of lipid metabolites and toxins to leak into extraintestinal tissues and circulation. It causes oxidative stress and hypoxia in local tissues and immune cell infiltration in various tissues, all contributing to the adaptation to this metabolic change. Immune cells transmit inflammatory responses in adipose and skeletal muscle tissue by secreting cytokines and adipokines, which mediate immune cell pathways and cause metaflammation and inefficient metabolic degradation. In this review, we focus on the regulatory function of the immunological microenvironment in the final metabolic outcome, with a particular emphasis on the cellular and molecular processes of local and systemic metaflammation induced by weight cycling-induced changes in body composition. Metaflammation in adipose and muscle tissues that is difficult to relieve may cause weight cycling. As this chronic low-grade inflammation spreads throughout the body, metabolic complications associated with weight cycling are triggered. Inhibiting the onset and progression of metabolic inflammation and enhancing the immune microenvironment of adipose and muscle tissues may be the first step in addressing weight cycling.

Total and regional appendicular skeletal muscle mass prediction from dual-energy X-ray absorptiometry body composition models

Sarcopenia, sarcopenic obesity, frailty, and cachexia have in common skeletal muscle (SM) as a main component of their pathophysiology. The reference method for SM mass measurement is whole-body magnetic resonance imaging (MRI), although dual-energy X-ray absorptiometry (DXA) appendicular lean mass (ALM) serves as an affordable and practical SM surrogate. Empirical equations, developed on relatively small and diverse samples, are now used to predict total body SM from ALM and other covariates; prediction models for extremity SM mass are lacking. The aim of the current study was to develop and validate total body, arm, and leg SM mass prediction equations based on a large sample (N = 475) of adults evaluated with whole-body MRI and DXA for SM and ALM, respectively. Initial models were fit using ordinary least squares stepwise selection procedures; covariates beyond extremity lean mass made only small contributions to the final models that were developed using Deming regression. All three developed final models (total, arm, and leg) had high R2s (0.88-0.93; all p < 0.001) and small root-mean square errors (1.74, 0.41, and 0.95 kg) with no bias in the validation sample (N = 95). The new total body SM prediction model (SM = 1.12 × ALM - 0.63) showed good performance, with some bias, against previously reported DXA-ALM prediction models. These new total body and extremity SM prediction models, developed and validated in a large sample, afford an important and practical opportunity to evaluate SM mass in research and clinical settings.

The Prevalence Rate of Adult Sarcopenic Obesity and Correlation of Appendicular Skeletal Muscle Mass Index with Body Mass Index, Percent Body Fat, Waist-Hip Ratio, Basal Metabolic Rate, and Visceral Fat Area

Background: This study aimed to investigate the prevalence rate of adult sarcopenic obesity and discuss its predisposing factors. Methods: A total of 14,608 participants including 7521 men and 7087 women aged 18-93 years were enrolled in this study. The definition of sarcopenia was based on appendicular skeletal muscle mass index (ASMI) standards (≤7.0 kg/m² for men and ≤5.7 grams/m² for women). The definition of obesity followed percent body fat (PBF) ≥25% for men and ≥35% for women. Sarcopenic obesity was defined as the combination of sarcopenia and obesity diagnosis. Risk factors for the onset of sarcopenic obesity were analyzed by logistic regression analysis, followed by diagnostic value assessment. Results: There were 496 cases of sarcopenic obesity, including 308 male patients and 188 female patients. The overall prevalence rate was 3.4%, with 4.10% for men and 2.65% for women. Compared with nonsarcogenic obesity group, the subjects with sarcogenic obesity showed shorter height and circumference of limbs, arm muscle, neck, chest, waist and hip, lighter weight, lower body mass index (BMI), bone mineral content (BMC), skeletal muscle mass, basal metabolic rate (BMR), body cell mass, fitness score and ASMI, and higher body fat mass, PBF, waist-hip ratio (WHR), visceral fat area (VFA), extracellular fluid/total body fat, and extracellular water/total body water (ECW/TBW; P < 0.01). Based on logistic regression analysis, BMI, BMC, PBF, WHR, BMR, VFA, fitness score, lean balance trunk, lean balance left leg, ASMI, ECW/TBW and the circumference of left arm, left leg, arm muscle, chest waist and hip were considered as risk factors for sarcogenic obesity (P < 0.05). After receiver operating characteristic (ROC) curve analysis of basic condition, muscle mass, and limb condition, ASMI [area under the curve (AUC) = 0.75] showed relatively high diagnostic value for adult sarcopenic obesity; other indicators (AUC <0.75) showed moderate diagnostic value for adult sarcopenic obesity, except for fitness score. According to joint ROC analysis, combination of BMC, PBF, VFA, and ASMI (AUC = 0.78) showed high diagnostic value for adult sarcopenic obesity. ASMI was correlated with BMI (r = 0.246, P < 0.001), BMC (r = 0.798, P < 0.001), WHR (r = 0.197, P < 0.001), BMR (r = 0.932, P < 0.001), PBF (r = -0.761, P < 0.001), and VFA (r = -0.530, P < 0.001). In adult patients with sarcopenic obesity, a decrease in ASMI indicators may be accompanied by a decrease in BMI, BMC, WHR, and BMR as well as an increase in PBF and VFA. Conclusion: The prevalence rate of adult sarcopenic obesity was 3.40%. ASMI was closely correlated with BMI, BMC, PBF, WHR, BMR, and VFA, which may serve as early indicators in the diagnosis of adult sarcopenic obesity.

Effects of a 4-month active weight loss phase followed by weight loss maintenance on adaptive thermogenesis in resting energy expenditure in former elite athletes

PURPOSE

Despite adaptive thermogenesis (AT) being studied as a barrier to weight loss (WL), few studies assessed AT in the resting energy expenditure (REE) compartment after WL maintenance. The aim of this study was twofold: (1) to understand if AT occurs after a moderate WL and if AT persists after a period of WL maintenance; and (2) if AT is associated with changes in body composition, hormones and energy intake (EI).

METHODS

Ninety-four participants [mean (SD); BMI, 31.1(4.3)kg/m2; 43.0(9.4)y; 34% female] were randomized to intervention (IG, n = 49) or control groups (CG, n = 45). Subjects underwent a 1-year lifestyle intervention, divided in 4 months of an active WL followed by 8 months of WL maintenance. Fat mass (FM) and fat-free mass (FFM) were measured by dual-energy X-ray absorptiometry and REE by indirect calorimetry. Predicted REE (pREE) was estimated through a model using FM, FFM. EI was measured by the "intake-balance" method.

RESULTS

For the IG, the weight and FM losses were - 4.8 (4.9) and - 11.3 (10.8)%, respectively (p < 0.001). A time-group interaction was found between groups for AT. After WL, the IG showed an AT of -85(29) kcal.d-1 (p < 0.001), and remained significant after 1 year [AT = - 72(31)kcal.d-1, p = 0.031]. Participants with higher degrees of restriction were those with an increased energy conservation (R = - 0.325, p = 0.036 and R = - 0.308, p = 0.047, respectively). No associations were found between diet adherence and AT. Following a sub-analysis in the IG, the group with a higher energy conservation showed a lower WL and fat loss and a higher initial EI.

CONCLUSION

AT in REE occurred after a moderate WL and remained significant after WL maintenance. More studies are needed to better clarify the mechanisms underlying the large variability observed in AT and providing an accurate methodological approach to avoid overstatements. Future studies on AT should consider not only changes in FM and FFM but also the FFM composition.

Unprocessed red meat in the dietary treatment of obesity: a randomized controlled trial of beef supplementation during weight maintenance after successful weight loss

BACKGROUND

Consumption of unprocessed red meat in randomized trials has no adverse effects on cardiovascular risk factors and body weight, but its physiological effects during weight loss maintenance are not known.

OBJECTIVES

We sought to investigate the effects of healthy diets that include small or large amounts of red meat on the maintenance of lost weight after successful weight loss, and secondarily on body composition (DXA), resting energy expenditure (REE; indirect calorimetry), and cardiometabolic risk factors.

METHODS

In this 5-mo parallel randomized intervention trial, 108 adults with BMI 28-40 kg/m2 (45 males/63 females) underwent an 8-wk rapid weight loss period, and those who lost ≥8% body weight (n = 80) continued to ad libitum weight maintenance diets for 12 wk: a moderate-protein diet with 25 g beef/d (B25, n = 45) or a high-protein diet with 150 g beef/d (B150, n = 35).

RESULTS

In per protocol analysis (n = 69), mean body weight (-1.2 kg; 95% CI: -2.1, -0.3 kg), mean fat mass (-2.7 kg; 95% CI: -3.4, -2.0 kg), and mean body fat content (-2.6%; 95% CI: -3.1, -2.1%) decreased during the maintenance phase, whereas mean lean mass (1.5 kg; 95% CI: 1.0, 2.0 kg) and mean REE (51 kcal/d; 95% CI: 15, 86 kcal/d) increased, with no differences between groups (all P > 0.05). Results were similar in intention-to-treat analysis with multiple imputation for dropouts (20 from B150 compared with 19 from B25, P = 0.929). Changes in cardiometabolic risk factors were not different between groups, the general pattern being a decrease during weight loss and a return to baseline during weight maintenance (and despite the additional mild reduction in weight and fat mass).

CONCLUSIONS

Healthy diets consumed ad libitum that contain a little or a lot of unprocessed beef have similar effects on body weight, energy metabolism, and cardiovascular risk factors during the first 3 mo after clinically significant rapid weight loss.

The Impact of the Rate of Weight Loss on Body Composition and Metabolism

PURPOSE OF REVIEW

Weight loss has multiple beneficial effects on body composition and metabolism, but whether these depend on the rate at which body weight is lost is not clear. We analyzed data from studies in which the same amount of weight loss was induced rapidly or gradually.

RECENT FINDINGS

Thirteen studies were included in which the same percentage weight loss was achieved at slow or fast rates (range: 0.2 to 3.2 kg/week) by means of dietary calorie restriction, exercise, and bariatric surgery. Faster rates of weight loss may result in more fat-free mass and less fat mass being lost during the dynamic phase of weight reduction compared with slower rates of weight loss, in conjunction with greater declines in resting energy expenditure. However, these differences are attenuated after 2-4 weeks of stabilization at the new, lower body weight, and do not affect the rate and amount of weight regain 9-33 months later (nor the tissue composition of regained weight). Differences in waist circumference, visceral and liver fat contents, resting blood pressure, fasting blood lipid profile, and insulin and adipokine concentrations in response to different rates of weight loss are trivial. The decline in fasting glucose concentration and the improvement in insulin sensitivity after 6-11% weight loss are both greater with rapid than gradual weight loss, but not different after 18-20% weight loss. Changes in body composition and metabolism after losing the same amount of body weight at different rates are largely similar, and occasional differences are likely not meaningful clinically for the long-term management of obesity and cardiometabolic diseases.

Effect of a Novel Intervention Targeting Appetitive Traits on Body Mass Index Among Adults With Overweight or Obesity: A Randomized Clinical Trial

Importance

Behavioral weight loss (BWL) programs result in weight loss for some, but most individuals regain the weight. The behavioral susceptibility theory proposes that genetically determined appetitive traits, such as food responsiveness (FR) and satiety responsiveness (SR), interact with the environment and lead to overeating and weight gain; the regulation of cues (ROC) intervention was developed specifically to target FR and SR.

Objective

To evaluate the efficacy of ROC, ROC combined with BWL (ROC+), BWL, and an active comparator (AC) over 12 months of treatment and 12 months of follow-up.

Design, Setting, and Participants

This randomized clinical trial was conducted from December 2015 to December 2019 in a university clinic. A total of 1488 volunteers from the community inquired about the study; 1217 were excluded or declined to participate. Eligibility criteria included body mass index (BMI) of 25 to 45, age 18 to 65 years, and lack of comorbidities or other exclusionary criteria that would interfere with participation. Data were analyzed from September 2021 to January 2022.

Interventions

ROC uniquely targeted FR and SR. BWL included energy restriction, increasing physical activity, and behavior therapy techniques. ROC+ combined ROC with BWL. AC included mindfulness, social support, and nutrition education.

Main Outcomes and Measures

Change in body weight as measured by BMI.

Results

A total of 271 adults (mean [SD] age, 46.97 [11.80] years; 81.6% female [221 participants]; mean [SD] BMI, 34.59 [5.28]; 61.9% White [167 participants]) were assessed at baseline, midtreatment, posttreatment, and 6-month and 12-month follow-up. Sixty-six participants were randomized to AC, 69 to ROC, 67 to ROC+, and 69 to BWL. Results showed that ROC, ROC+, and BWL interventions resulted in significantly lower BMI at the end of treatment (BMI ROC, -1.18; 95% CI, -2.10 to -0.35; BMI ROC+, -1.56; 95% CI, -2.43 to -0.67; BMI BWL, -1.58; 95% CI, -2.45 to -0.71). Compared with BWL, BMI at the end of treatment was not significantly different from ROC or ROC+ (BMI ROC, 0.40; 95% CI, -0.55 to 1.36; BMI ROC+, 0.03; 95% CI, -0.88 to 0.93); however, the BMI of the AC group was substantially higher (BMI AC, 1.58; 95% CI, 0.72 to 2.45). BMI reductions at 24 months after randomization were similar for ROC, ROC+, and BWL. Importantly, FR was a moderator of treatment effects with more weight loss for participants who scored higher in FR in the ROC and ROC+ groups.

Conclusions and Relevance

These findings suggest that ROC and ROC+ provide alternative weight loss approaches for adults. These models could be particularly effective for individuals who struggle with FR and could be used as a precision approach for weight loss.

Trial Registration

ClinicalTrials.gov Identifier: NCT02516839.

Cold exposure prevents fat accumulation in striped hamsters refed a high-fat diet following food restriction

Background

In mammals, body mass lost during food restriction is often rapidly regained, and fat is accumulated when ad libitum feeding is resumed. Studies in small cold-acclimated mammals have demonstrated significant mobilization of fat deposits during cold exposure to meet the energy requirements of metabolic thermogenesis. However, no studies to our knowledge have examined the effect of cold exposure on fat accumulation during body mass recovery when refed ad libitum. In this study, striped hamsters restricted to 80% of their regular food intake were then refed ad libitum and exposed to one of three conditions: Intermittent cold temperature (5 °C) for 2 h per day (ICE-2 h/d), intermittent cold temperature (5 °C) for 12 h per day (ICE-12 h/d), or persistent cold exposure (PCE) for four weeks. We measured energy intake, fat deposit mass, serum thyroid hormone levels, and uncoupling protein 1 expression in brown adipose tissue.

Results

There was no significant effect of intermittent or persistent cold exposure on body mass regain, whereas energy intake increased significantly and total fat deposit decreased in the ICE-12 h/d and PCE groups compared to the ICE-2 h/d group and control group maintained at 23 °C (CON). In the ICE-12 h/d and PCE groups, hamsters had 39.6 and 38.3% higher serum 3,3′,5-triiodothyronine levels, respectively, and 81.6 and 71.3% up-regulated expression of uncoupling protein 1, respectively, in brown adipose tissue compared to their counterparts in the CON group. The rate of mitochondrial state III and state IV respiration O2 consumption and the activity of cytochrome c oxidase in BAT and liver were significantly higher in the ICE-12 h/d and PCE groups than in the ICE-2 h/d and CON groups.

Conclusions

Our findings suggest thyroid hormone-mediated heat production in brown adipose tissue and liver may be involved in preventing fat accumulation during refeeding in animals frequently or persistently exposed to cold conditions.

Adaptive thermogenesis after moderate weight loss: magnitude and methodological issues

PURPOSE

The aim of this study was (1) to assess AT through 13 different mathematical approaches and to compare their results; and (2) to understand if AT occurs after moderate WL.

METHODS

Ninety-four participants [mean (SD); BMI, 31.1 (4.3) kg/m2; age, 43.0 (9.4) years; 34% females] underwent a 1-year lifestyle intervention (clinicaltrials.gov ID: NCT03031951) and were randomized to intervention (IG, n = 49) or control groups (CG, n = 45), and all measurements were made at baseline and after 4 months. Fat mass (FM) and fat-free mass (FFM) were measured by dual-energy X-ray absorptiometry and REE by indirect calorimetry. AT was assessed through 13 different approaches, varying in how REE was predicted and/or how AT was assessed.

RESULTS

IG underwent a mean negative energy balance (EB) of 270 (289) kcal/day, p < 0.001), resulting in a WL of - 4.8 (4.9)% and an FM loss of - 11.3 (10.8)%. Regardless of approach, AT occurred in the IG, ranging from ~ - 65 to ~ - 230 kcal/day and three approaches showed significant AT in the CG.

CONCLUSIONS

Regardless of approach, AT occurred after moderate WL in the IG. AT assessment should be standardized and comparisons among studies with different methodologies to assess AT must be avoided.

Phenotypic differences between people varying in muscularity

BACKGROUND

Body mass is the primary metabolic compartment related to a vast number of clinical indices and predictions. The extent to which skeletal muscle (SM), a major body mass component, varies between people of the same sex, weight, height, and age is largely unknown. The current study aimed to explore the magnitude of muscularity variation present in adults and to examine if variation in muscularity associates with other body composition and metabolic measures.

METHODS

Muscularity was defined as the difference (residual) between a person's actual and model-predicted SM mass after controlling for their weight, height, and age. SM prediction models were developed using data from a convenience sample of 492 healthy non-Hispanic (NH) White adults (ages 18-80 years) who had total body SM and SM surrogate, appendicular lean soft tissue (ALST), measured with magnetic resonance imaging and dual-energy X-ray absorptiometry, respectively; residual SM (SM_R ) and ALST were expressed in kilograms and kilograms per square meter. ALST mass was also evaluated in a population sample of 8623 NH-White adults in the 1999-2006 National Health and Nutrition Examination Survey. Associations between muscularity and variation in the residual mass of other major organs and tissues and resting energy expenditure were evaluated in the convenience sample.

RESULTS

The SM, on average, constituted the largest fraction of body weight in men and women up to respective BMIs of 35 and 25 kg/m² . SM in the convenience sample varied widely with a median of 31.2 kg and an SM_R inter-quartile range/min/max of 3.35 kg/-10.1 kg/9.0 kg in men and 21.1 kg and 2.59 kg/-7.2 kg/7.5 kg in women; per cent of body weight as SM at 25th and 75th percentiles for men were 33.1% and 39.6%; corresponding values in women were 24.2% and 30.8%; results were similar for SM_R indices and for ALST measures in the convenience and population samples. Greater muscularity in the convenience sample was accompanied by a smaller waist circumference (men/women: P < 0.001/=0.085) and visceral adipose tissue (P = 0.014/0.599), larger liver (P = 0.065/<0.001), kidneys (P = 0.051/<0.009), and bone mineral (P < 0.001/<0.001), and larger magnitude resting energy expenditure (P < 0.001/<0.001) than predicted for the same sex, age, weight, and height.

CONCLUSIONS

Muscle mass is the largest body compartment in most adults without obesity and is widely variable in mass across people of similar body size and age; and high muscularity is accompanied by distinct body composition and metabolic characteristics. This previously unrecognized heterogeneity in muscularity in the general population has important clinical and research implications.

Workplace wellness programs targeting weight outcomes in men: A scoping review

Workplaces have been identified as a priority setting for the delivery of wellness programs to address risk factors for overweight and obesity. Men in particular may benefit greatly from these types of programs as they are typically harder to engage in health promotion. A scoping review was performed to provide an overview of interventions that have been implemented within the workplace that target weight outcomes in men. A searched of six electronic databases (Medline, Embase, CINAHL, Scopus, Cochrane Database of Systematic Review, and Business Source Ultimate) was conducted from January 2010 to August 2020. Of the 2191 articles identified, 25 were included. The majority took place in North America or Europe (72%). Over half (n = 17, 68%) utilized both a nutrition and physical activity component. Thirteen of the 19 articles (68%) that reported weight as an outcome showed the program to be efficacious in reducing weight. Overall, only seven articles were solely focused on an all-male population. Workplace wellness programs targeting weight outcomes in men have been conducted to some extent, with majority being successful in reducing weight. However, there is a need for more randomized controlled trials (RCTs), long-term follow-up, and male-only programs.

Does adaptive thermogenesis occur after weight loss in adults? A systematic review

Adaptive thermogenesis (AT) has been proposed to be a compensatory response that may resist weight loss (WL) and promote weight regain. This systematic review examined the existence of AT in adults after a period of negative energy balance (EB) with or without a weight stabilisation phase. Studies published until 15 May 2020 were identified from PubMed, Cochrane Library, EMBASE, MEDLINE, SCOPUS and Web of Science. Inclusion criteria included statistically significant WL, observational with follow-up or experimental studies, age > 18y, sample size ≥10 participants, intervention period ≥ 1week, published in English, objective measures of total daily energy expenditure (EE) (TDEE), resting EE (REE) and sleeping EE(SEE). The systematic review was registered at PROSPERO (2020 CRD42020165348). A total of thirty-three studies comprising 2528 participants were included. AT was observed in twenty-seven studies. Twenty-three studies showed significant values for AT for REE (82·8 %), four for TDEE (80·0 %) and two for SEE (100 %). A large heterogeneity in the methods used to quantify AT and between subjects and among studies regarding the magnitude of WL and/or of AT was reported. Well-designed studies reported lower or non-significant values for AT. These findings suggest that although WL may lead to AT in some of the EE components, these values may be small or non-statistically significant when higher-quality methodological designs are used. Furthermore, AT seems to be attenuated, or non-existent, after periods of weight stabilisation/neutral EB. More high-quality studies are warranted not only to disclose the existence of AT but also to understand its clinical implications on weight management outcomes.

A protein-supplemented very-low-calorie diet does not mitigate reductions in lean mass and resting metabolic rate in subjects with overweight or obesity: A randomized controlled trial

BACKGROUND & AIMS

The European Food Safety Authority recently recommended an increase in the protein content of total diet replacement (TDR) products from 50 to 75 g/day. The rationale was to minimize reductions in lean mass (LM) and resting metabolic rate (RMR) that occur with weight loss, and thereby facilitate maintenance of lost weight. We sought to directly compare the efficacy of TDR regimens with the new vs the current protein requirement.

METHODS

We randomized 108 adults with overweight or obesity (body mass index 28-40 kg/m²) to very-low-calorie diets (VLCD) with either 52 or 77 g/day protein for 8 weeks (total energy intake of 600 or 700 kcal/day, respectively). LM was determined by dual energy X-ray absorptiometry and RMR by indirect calorimetry.

RESULTS

Attrition rate was 22% in both groups. Both VLCDs decreased body weight, fat mass, LM, and RMR (all P < 0.05). Significant time-by-group interactions were detected for weight and fat mass (both P < 0.05), with corresponding reductions being smaller in the higher-protein than the standard-protein VLCD, likely because of the added calories. On the other hand, reductions in LM (6% from baseline) and RMR (9-10% from baseline) did not differ between groups (P = 0.155 and P = 0.389, respectively), and the contribution of LM to total weight loss was identical (27 ± 2% of lost weight, P = 0.973).

CONCLUSIONS

Our results indicate that the proposed increase in the protein content of TDR products does not attenuate reductions in LM and RMR in individuals with overweight and obesity who are treated with <800 kcal/day VLCDs for 2 months.

CLINICAL TRIAL REGISTRY

ClinicalTrials.gov # NCT04156165.

Obesity treatment: Weight loss versus increasing fitness and physical activity for reducing health risks

We propose a weight-neutral strategy for obesity treatment on the following grounds: (1) the mortality risk associated with obesity is largely attenuated or eliminated by moderate-to-high levels of cardiorespiratory fitness (CRF) or physical activity (PA), (2) most cardiometabolic risk markers associated with obesity can be improved with exercise training independent of weight loss and by a magnitude similar to that observed with weight-loss programs, (3) weight loss, even if intentional, is not consistently associated with lower mortality risk, (4) increases in CRF or PA are consistently associated with greater reductions in mortality risk than is intentional weight loss, and (5) weight cycling is associated with numerous adverse health outcomes including increased mortality. Adherence to PA may improve if health care professionals consider PA and CRF as essential vital signs and consistently emphasize to their patients the myriad benefits of PA and CRF in the absence of weight loss.

Effect of 2-year caloric restriction on organ and tissue size in nonobese 21- to 50-year-old adults in a randomized clinical trial: the CALERIE study

BACKGROUND

Sustained calorie restriction (CR) promises to extend the lifespan. The effect of CR on changes in body mass across tissues and organs is unclear.

OBJECTIVES

We used whole-body MRI to evaluate the effect of 2 y of CR on changes in body composition.

METHODS

In an ancillary study of the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE) trial, 43 healthy adults [25-50 y; BMI (kg/m2): 22-28] randomly assigned to 25% CR (n = 28) or ad libitum (AL) eating (n = 15) underwent whole-body MRI at baseline and month 24 to measure adipose tissue in subcutaneous, visceral, and intermuscular depots (SAT, VAT, and IMAT, respectively); skeletal muscle; and organs including brain, liver, spleen, and kidneys but not heart.

RESULTS

The CR group lost more adipose tissue and lean tissue than controls (P < 0.05). In the CR group, at baseline, total tissue volume comprised 32.1%, 1.9%, and 1.0% of SAT, VAT, and IMAT, respectively. The loss of total tissue volume over 24 mo comprised 68.4%, 7.4%, and 2.2% of SAT, VAT, and IMAT, respectively, demonstrating preferential loss of fat vs. lean tissue. Although there is more muscle loss in CR than AL (P < 0.05), the loss of muscle over 24 mo in the CR group comprised only 17.2% of the loss of total tissue volume. Changes in organ volumes were not different between CR and AL. The degree of CR (% decrease in energy intake vs. baseline) significantly (P < 0.05) affected changes in VAT, IMAT, muscle, and liver volume (standardized regression coefficient ± standard error of estimates: 0.43 ± 0.15 L, 0.40 ± 0.19 L, 0.55 ± 0.17 L, and 0.45 ± 0.18 L, respectively).

CONCLUSIONS

Twenty-four months of CR (intended, 25%; actual, 13.7%) in young individuals without obesity had effects on body composition, including a preferential loss of adipose tissue, especially VAT, over the loss of muscle and organ tissue. This trial was registered at www.clinicaltrials.gov as NCT02695511.

Sexual Dimorphism in Body Weight Loss, Improvements in Cardiometabolic Risk Factors and Maintenance of Beneficial Effects 6 Months after a Low-Calorie Diet: Results from the Randomized Controlled DiOGenes Trial

A low-calorie diet (LCD) is an effective strategy to lose weight and improve cardiometabolic risk factors, however, sexual dimorphism may be present. This study aims to investigate sexual dimorphism in cardiometabolic risk factors following weight loss and after weight maintenance. 782 overweight/obese participants (65% women) of the DiOGenes trial followed an 8-week LCD (~800 kcal/day), with a 6-months follow-up weight maintenance period on ad libitum diets varying in protein content and glycemic index. Men lost more body weight during the LCD period (−12.8 ± 3.9 vs. −10.1 ± 2.8 kg, respectively, p < 0.001), but regained more weight during the follow-up period than women (1.5 ± 5.4 vs. −0.5 ± 5.5 kg, respectively, p < 0.001). Even though beneficial LCD-induced changes in cardiometabolic risk factors were found for both sexes, improvements in HOMA-IR, muscle and hepatic insulin sensitivity, triacylglycerol, HDL−, LDL− and total cholesterol, diastolic blood pressure, cholesterol esters, sphingomyelins and adiponectin were more pronounced in men than women (std. ß range: 0.073–0.144, all q < 0.05), after adjustment for weight change. During follow-up, women demonstrated a lower rebound in HDL-cholesterol, triacylglycerol and diacylglycerol (std. ß range: 0.114–0.164, all q < 0.05), independent of changes in body weight. Overall, we demonstrated sexual dimorphism in LCD-induced changes in body weight and cardiometabolic risk profile, which may be attributed to differences in body fat distribution and metabolic status.

Changes in body composition and low blood urea nitrogen level related to an increase in the prevalence of fatty liver over 20 years: A cross-sectional study

AIM

Qualitative body composition (BC) change, characterized by the combination of visceral fat gain and muscle loss, is drawing attention as a risk factor for fatty liver (FL). The present study aimed to describe trends in BC change and its association with FL in the Japanese population.

METHODS

Data from medical checkups carried out on 56 639 Japanese participants every 5 years from 1997 to 2017 were analyzed. Fat mass index (FMI) and fat-free mass index (FFMI) were calculated using body mass index and body fat percentage. Subjects were divided into two groups according to deviations from the correlation line of FMI and FFMI as the reference: FMI-predominant BC and FFM-dominant BC. Fatty liver was determined using abdominal ultrasonography.

RESULTS

The prevalence of FL significantly increased from 27.3% to 42.7% in men and from 18.0% to 25.5% in women. The prevalence of FMI predominance significantly increased from 33.6% to 43.9% in men and from 29.1% to 47.0% in women. Fat mass index predominance was independently associated with FL in men and women (odds ratio: 1.96 and 1.94, respectively). Serum blood urea nitrogen level was inversely associated with FL in men and women (0.958 and 0.961, respectively) and significantly decreased from 15.8 to 14.9 mg/dl in men and from 15.1 to 14.0 mg/dl in women.

CONCLUSIONS

Increasing FMI-predominant BC and decreasing serum blood urea nitrogen level could account for the increase in the prevalence of FL over 20 years. We believe that these factors stem from current lifestyle habits in Japan.

Describing the Weight-Reduced State: Physiology, Behavior, and Interventions

Although many persons with obesity can lose weight by lifestyle (diet and physical activity) therapy, successful long-term weight loss is difficult to achieve, and most people who lose weight regain their lost weight over time. The neurohormonal, physiological, and behavioral factors that promote weight recidivism are unclear and complex. The National Institute of Diabetes and Digestive and Kidney Diseases convened a workshop in June 2019, titled "The Physiology of the Weight-Reduced State," to explore the mechanisms and integrative physiology of adaptations in appetite, energy expenditure, and thermogenesis that occur in the weight-reduced state and that may oppose weight-loss maintenance. The proceedings from the first session of this workshop are presented here. Drs. Michael Rosenbaum, Kevin Hall, and Rudolph Leibel discussed the physiological factors that contribute to weight regain; Dr. Michael Lowe discussed the biobehavioral issues involved in weight-loss maintenance; Dr. John Jakicic discussed the influence of physical activity on long-term weight-loss maintenance; and Dr. Louis Aronne discussed the ability of drug therapy to maintain weight loss.

Diagnosis of obesity based on body composition-associated health risks-Time for a change in paradigm

Traditional diagnosis and understanding of the pathophysiology of obesity are based on excessive fat storage due to a chronically positive energy balance characterized by body mass index (BMI). Quantitative and qualitative analysis of lean and adipose tissue compartments by body composition analysis reveals that characterization of obesity as "overfat" does not facilitate a comprehensive understanding of obesity-associated health risk. Instead of being related to fat mass, body composition characteristics underlying BMI-associated prognosis may depend (i) on accelerated growth by a gain in lean mass or fat-free mass (FFM) in children with early BMI rebound or adolescents with early puberty; (ii) on a low muscle mass in aging, associated chronic disease, or severe illness; and (iii) on impaired adipose tissue expandability with respect to cardiometabolic risk. It is therefore time to call the adipocentric paradigm of obesity into question and to avoid the use of BMI and body fat percentage. By contrast, obesity should be seen in face of a limited FFM/muscle mass together with a limited capacity of fat storage.

From famine to therapeutic weight loss: Hunger, psychological responses, and energy balance-related behaviors

Understanding physiological and behavioral responses to energy imbalances is important for the management of overweight/obesity and undernutrition. Changes in body composition and physiological functions associated with energy imbalances provide the structural and functional context in which to consider psychological and behavioral responses. Compensatory changes in physiology and behavior are more pronounced in response to negative than positive energy balances. The physiological and psychological impact of weight loss (WL) occur on a continuum determined by (i) the degree of energy deficit (ED), (ii) its duration, (iii) body composition at the onset of the energy deficit, and (iv) the psychosocial environment in which it occurs. Therapeutic WL and famine/semistarvation both involve prolonged EDs, which are sometimes similar in magnitude. The key differences are that (i) the body mass index (BMI) of most famine victims is lower at the onset of the ED, (ii) therapeutic WL is intentional and (iii) famines are typically longer in duration (partly due to the voluntary nature of therapeutic WL and disengagement with WL interventions). The changes in psychological outcomes, motivation to eat, and energy intake in therapeutic WL are often modest (bearing in mind the nature of the measures used) and can be difficult to detect but are quantitatively significant over time. As WL progresses, these changes become more marked. It appears that extensive WL beyond 10%-20% in lean individuals has profound effects on body composition and physiological function. At this level of WL, there is a marked erosion of psychological functioning, which appears to run in parallel to WL. Psychological resources dwindle and become increasingly focused on alleviating escalating hunger and food seeking behavior. Functional changes in fat-free mass, characterized by catabolism of skeletal muscle and organs may be involved in the drive to eat associated with semistarvation. Higher levels of body fat mass may act as a buffer to protect fat-free mass, functional integrity and limit compensatory changes in energy balance behaviors. The increase in appetite that accompanies therapeutic WL appears to be very different to the intense and all-consuming drive to eat that occurs during prolonged semistarvation. The mechanisms may also differ but are not well understood, and longitudinal comparisons of the relationship between body structure, function, and behavior in response to differing EDs in those with higher and lower BMIs are currently lacking.

The effects of weight fluctuation on the components of metabolic syndrome: a 16-year prospective cohort study in South Korea

Background

Weight fluctuation (WF) is highly prevalent in parallel with the high prevalence of intentional or unintentional dieting. The health risks of frequent WF for metabolic syndrome (MS) have become a public health concern, especially for health care providers who supervise dieting as an intervention to prevent obesity-related morbidity or to improve health, as well as for the general population for whom dieting is of interest. The aim of this study was to investigate the long-term effect of WF on the risk of MS in Koreans.

Methods

This study analyzed secondary data from the Korean Genome and Epidemiology Study, a 16-year prospective cohort study, on 8150 individuals using time-dependent Cox regression.

Results

WF did not increase the risk of MS in either normal-weight or obese subjects. In an analysis of the components of MS, greater WF significantly increased the risk of abdominal obesity (HR = 1.05, 95% CI = 1.02–1.07, p < 0.001) in normal-weight individuals. However, WF did not increase the risk of hyperglycemia, low high-density lipoprotein cholesterol levels, elevated blood pressure, or raised fasting glucose in normal-weight individuals, and it did not influence any of the components of MS in obese individuals.

Conclusion

Since WF was found to be a risk factor for abdominal obesity, which is the most reliable predictor of MS, it should be considered when addressing weight control. Further studies on cut-off points for the degree of weight loss in a certain period need to be conducted to help clinicians provide guidance on appropriate weight control.

Reduced metabolic efficiency in sedentary eucaloric conditions predicts greater weight regain in adults with obesity following sustained weight loss

Background

Successful long-term weight loss maintenance after caloric restriction (CR) is rarely achieved. Besides known metabolic, behavioral, and cognitive factors, 24-hour energy expenditure (24hEE) relative to body size (i.e., metabolic efficiency) might influence subsequent weight loss maintenance.

Methods

Eleven participants with obesity (BMI=39.0±8.7 kg/m², body fat=36.1±6.4%) had 24hEE measured in a whole-room indirect calorimeter during eucaloric conditions and weight stability prior to starting a 6-week inpatient CR study (50% of daily energy needs). Twenty-four-hour energy expenditure was adjusted via regression analysis for fat free mass (FFM) and fat mass (FM) by DXA. Body composition was reassessed at the end of CR and after 1-year follow-up. Free-living weight was assessed by monthly weight measurements during 12 months.

Results

After 6-week CR, participants lost 8.5±2.7% weight (FFM: −6.3±3.6 kg, FM: −3.4±1.2 kg) but regained 5.1±8.0% one year following CR, which was mostly due to FFM regain (+5.7±5.5 kg) and unchanged FM. A relatively higher 24hEE by 100 kcal/day prior to CR was associated with an average greater rate of weight regain by +0.3 kg/month during follow-up and a greater final weight regain by +5.1 kg after 1 year of follow-up.

Conclusion

These results suggest that reduced metabolic efficiency in 24hEE during eucaloric, sedentary conditions may predict greater weight regain after CR-induced weight loss.

Impact of Protein Intake during Weight Loss on Preservation of Fat-Free Mass, Resting Energy Expenditure, and Physical Function in Overweight Postmenopausal Women: A Randomized Controlled Trial

INTRODUCTION

Weight loss in old age increases the risk of sarcopenia caused by the age-related reduction of fat-free mass (FFM). Due to the strong correlation between FFM and resting energy expenditure (REE), the maintenance of this must also be considered. Besides, the physical function (PF) must be maintained.

OBJECTIVE

The impact of protein intake on changes in FFM, REE, and PF during weight loss in overweight postmenopausal women was investigated.

METHODS

Fifty-four postmenopausal women (BMI 30.9 ± 3.4; age 59 ± 7 years) were randomized into 2 groups receiving energy-restricted diets with either 0.8 g (normal protein; NP) or 1.5 g protein/kg body weight (high protein; HP) for 12 weeks, followed by a 6-month follow-up phase with an ad libitum food intake. FFM, REE, and PF (strength, endurance, and balance) were measured at baseline, after weight loss, and after follow-up.

RESULTS

Forty-six women completed the weight loss intervention and 29 were followed up. The weight loss was -4.6 ± 3.6 kg (HP) and -5.2 ± 3.4 kg (NP; both p < 0.001) and the weight regain during follow-up was 1.3 ± 2.8 kg (HP; p = 0.03) and 0.4 ± 2.5 kg (NP; p = 0.39), with no differences between groups. Similar decreases in FFM (-0.9 ± 1.1 [HP] vs. -1.0 ± 1.3 kg [NP]) and REE (-862 ± 569 [HP] vs. -1,000 ± 561 kJ [NP]; both p < 0.001) were observed in both groups. During follow-up, no changes in FFM were detected in either group, whereas in the NP group the REE increased again (+138 ± 296; p = 0.02). The main determinants of FFM loss were the energy deficit and the speed of weight loss. In the NP group, the Short Physical Performance Battery score improved with weight loss (+0.6 ± 0.8; p < 0.001) and handgrip strength decreased (-1.7 ± 3.4 kg; p < 0.001), whereas no changes were observed in the HP group.

CONCLUSIONS

An HP weight-loss diet without exercise had no impact on preservation of FFM and REE but may help to maintain muscle strength in postmenopausal women.

Early adaptive thermogenesis is a determinant of weight loss after six weeks of caloric restriction in overweight subjects

BACKGROUND

Adaptive thermogenesis during prolonged energy deficit refers to the greater than expected reduction in energy expenditure (EE) independent of concomitant loss of metabolically active body mass.

OBJECTIVE

As inter-individual variability in the magnitude of adaptive thermogenesis may influence the extent of energy deficit thereby predicting the amount of weight reduction, we investigated whether early adaptive thermogenesis is a determinant of weight loss after 6 weeks of daily 50% caloric restriction in an inpatient setting.

DESIGN AND METHODS

The current study reports the results of an exploratory, secondary analysis in overweight but otherwise healthy subjects (n = 11, 7 men, 35 ± 9y, BMI = 40 ± 7 kg/m², body fat = 63.3 ± 5.3%). Body composition and 24-h EE (24hEE) measurement in a whole-room indirect calorimeter were used to calculate the magnitude of adaptive thermogenesis while on caloric restriction after 1, 3 and 6 weeks. Energy deficit during caloric restriction was quantified via food, stool, and urine bomb calorimetry. Fasting hormonal concentrations (FT4, FT3, FGF21, leptin) were obtained at baseline and at weeks 3 and 6 during caloric restriction.

RESULTS

The magnitude of adaptive thermogenesis in 24hEE after 1 week of caloric restriction was -178 ± 137 kcal/day (mean ± SD), was overall stable during and following caloric restriction, and demonstrated remarkable intra-individual consistency. A relatively greater decrease in 24hEE of 100 kcal/d after 1 week of caloric restriction was associated on average with reduced energy deficit by 8195 kcal over 6 weeks and predicted 2.0 kg less weight loss, of which 0.5 kg was fat mass, after 6 weeks. No correlations were found between hormonal concentrations and weight loss.

CONCLUSIONS

The extent of weight loss is influenced by the magnitude of adaptive thermogenesis in the early stage of caloric restriction. Although these results need replication in larger study groups with adequate statistical power, targeting adaptive thermogenesis may help to optimize long-term interventions in obesity therapy.

Lifetime Weight Cycling and Central Fat Distribution in Females With Obesity: A Brief Report

Weight cycling (WC) is a common phenomenon in patients with obesity, however, its consequence on body composition has not yet been fully understood. Therefore, we aimed to determine whether multiple WC can negatively affect the latter, especially in terms of body fat distribution in female adults seeking treatment that are overweight or obese. Body composition was obtained using a segmental body composition analyser (MC-780MA, Tanita Corp., Tokyo, Japan) in 125 adult females who had been referred to the Department of Nutrition and Dietetics at the Beirut Arab University (Lebanon). WC was defined as intentional weight loss of ≥3 kg followed by involuntary weight regain of ≥3 kg, and participants were categorized as WC if they had experienced ≥2 cycles. Ninety of the 125 participants met the criteria for WC and displayed a higher total and trunk fat mass than those without WC. This was confirmed through linear regression analysis, showing that multiple WC were associated with increased fat mass (FM) by nearly 4.2 kg (β = 4.23, 95%CI: 0.81-7.65, p = 0.016)-2.4 kg in the trunk region (β = 2.35, 95%CI: 0.786-3.917, p = 0.004) when compared to the non-WC group, after adjusting for age and fat-free mass. In conclusion, multiple WC is associated with increased body fat, especially in the central region. Future studies are needed to examine the impact of this fat distribution on health outcomes in this phenotype of patients.

Push Notifications From a Mobile App to Improve the Body Composition of Overweight or Obese Women: Randomized Controlled Trial

Background

Technology—in particular, access to the Internet from a mobile device—has forever changed the way we relate to others and how we behave in our daily life settings. In recent years, studies have been carried out to analyze the effectiveness of different actions via mobile phone in the field of health: telephone calls, short message service (SMS), telemedicine, and, more recently, the use of push notifications. We have continued to explore ways to increase user interaction with mobile apps, one of the pending subjects in the area of mHealth. By analyzing the data produced by subjects during a clinical trial, we were able to extract behavior patterns and, according to them, design effective protocols in weight loss programs.

Objective

A clinical trial was proposed to (1) evaluate the efficacy of push notifications in an intervention aimed at improving the body composition of adult women who are overweight or obese, through a dietary procedure, and (2) analyze the evolution of body composition based on push notifications and prescribed physical activity (PA).

Methods

A two-arm randomized controlled trial was carried out. A sample size of 117 adult obese women attended a face-to-face, 30-minute consultation once a week for 6 months. All patients were supplied with an app designed for this study and a pedometer. The control group did not have access to functionalities related to the self-monitoring of weight at home, gamification, or prescription of PA. The intervention group members were assigned objectives to achieve a degree of compliance with diet and PA through exclusive access to specific functionalities of the app and push notifications. The same diet was prescribed for all patients. Three possible PA scenarios were studied for both the control and intervention groups: light physical activity (LPA), moderate physical activity (MPA), and intense physical activity (IPA). For the analysis of three or more means, the analysis of variance (ANOVA) of repeated means was performed to evaluate the effects of the intervention at baseline and at 3 and 6 months.

Results

Receiving notifications during the intervention increased body fat loss (mean -12.9% [SD 6.7] in the intervention group vs mean -7.0% [SD 5.7] in the control group; P<.001) and helped to maintain muscle mass (mean -0.8% [SD 4.5] in the intervention group vs mean -3.2% [SD 2.8] in the control group; P<.018). These variations between groups led to a nonsignificant difference in weight loss (mean -7.9 kg [SD 3.9] in the intervention group vs mean -7.1 kg [SD 3.4] in the control group; P>.05).

Conclusions

Push notifications have proven effective in the proposed weight loss program, leading women who received them to achieve greater loss of fat mass and a maintenance or increase of muscle mass, specifically among those who followed a program of IPA. Future interventions should include a longer evaluation period; the impact of different message contents, as well as message delivery times and frequency, should also be researched.

Trial Registration

ClinicalTrials.gov NCT03911583; https://www.clinicaltrials.gov/ct2/show/NCT03911583

Changes in body composition with a hypocaloric diet combined with sedentary, moderate and high-intense physical activity: a randomized controlled trial

BACKGROUND

There is evidence showing the effectiveness of a hypocaloric diet and the increase in physical activity on weight loss. However, the combined role of these factors, not only on weight loss but also body composition, remains unclear. The purpose of this study was to investigate the effect of a hypocaloric diet on the body composition of obese adult women throughout different degrees of physical activity during a weight loss program.

METHODS

One hundred and seventeen healthy female volunteers were randomly assigned to one of the experimental groups: a control group with a low-level prescription of physical activity (1-4 METs), moderate physical activity group that performed 10.000 steps walking (5-8 METs) and intense physical activity group that trained exercises by at least 70% of VO2max three times a week (> 8 METs). All subjects followed a hypocaloric diet designed with a reduction of 500 kcal/day. Nutritional counseling was provided throughout the study period to help ensure dietary adherence.

RESULTS

We found no differences in body weight compared to moderate and intense physical activity (ßstand. = - 0.138 vs. ßstand. = - 0.139). Body fat was lower in women following an intense activity (ßstand. = - 0.436) than those with moderate exercise (ßstand. = - 0.231). The high-intense activity also increased muscle mass at the end of the intervention, standing out above the moderate activity (ßstand. = 0.182 vs. ßstand. = 0.008).

CONCLUSIONS

These findings indicate that a hypocaloric diet, without prescription of physical activity, is adequate to lose weight in the short term (12 weeks), but physical activity is vital to modify the body composition in women with obesity. Body fat was lower when women practiced a moderate exercise compared to hypocaloric diet only, but an intense physical activity was the most effective protocol to obtain a reduction of body fat and maintain muscle mass.

TRIAL REGISTRATION

The study protocol complied with the Declaration of Helsinki for medical studies, it was approved by the bioethical committee of Córdoba University, in the Department of Health at the Regional Government of Andalusia (Act n°284, ref.4156) and retrospectively registered in clinicaltrials.gov (NCT03833791). Registered 2 January 2019.

Is There a Contribution of Structural Brain Phenotypes to the Variance in Resting Energy Expenditure before and after Weight Loss in Overweight Females?

Brain gray (GM) and white matter (WM) are associated with resting energy expenditure (REE). The impact of weight loss on GM and WM masses, as well as on their associations with REE and the ratio between body and brain metabolism, i.e., encephalic measure (EM)), are unknown. Longitudinal data of 69 female Caucasian subjects (age range 19–69 years) with detailed information on fat mass (FM), fat free mas (FFM), GM, WM and REE. Mean weight loss was 14.5 ± 11.9 kg with changes in FM (−12.9 ± 9.8 kg), FFM (−1.7 ± 4.8 kg) and REE (−159 ± 191 kcal/24 h) (all p < 0.05). With weight loss, there were no changes in GM and WM. Before and after weight loss, FFM was the main determinant of REE (r² = 0.483 and 0.413; p < 0.05). After weight loss, GM added to the variances in REE (3.6%), REE_adjFFM (6.1%) and the REE on FFM residuals (6.6%). In addition, before and after weight loss GM explained 25.0% and 10.0% of the variances in EM (p < 0.05). Weight loss had no effect on volumes of GM and WM. After weight loss, both, GM added to the variances of REE, REE on FFM residuals and EM.

Associations between the rate, amount, and composition of weight loss as predictors of spontaneous weight regain in adults achieving clinically significant weight loss: A systematic review and meta-regression

Weight regain following weight loss is common although little is known regarding the associations between amount, rate, and composition of weight loss and weight regain. Forty-three studies (52 groups; n = 2379) with longitudinal body composition measurements were identified in which weight loss (≥5%) and subsequent weight regain (≥2%) occurred. Data were synthesized for changes in weight and body composition. Meta-regression models were used to investigate associations between amount, rate, and composition of weight loss and weight regain. Individuals lost 10.9% of their body weight over 13 weeks composed of 19.6% fat-free mass, followed by a regain of 5.4% body weight over 44 weeks composed of 21.6% fat-free mass. Associations between the amount (P < 0.001) and rate (P = 0.049) of weight loss and their interaction (P = 0.042) with weight regain were observed. Fat-free mass (P = 0.017) and fat mass (P < 0.001) loss both predicted weight regain although the effect of fat-free mass was attenuated following adjustment. The amount (P < 0.001), but not the rate of weight loss (P = 0.150), was associated with fat-free mass loss. The amount and rate of weight loss were significant and interacting factors associated with weight regain. Loss of fat-free mass and fat mass explained greater variance in weight regain than weight loss alone.

Weight Cycling as a Risk Factor for Low Muscle Mass and Strength in a Population of Males and Females with Obesity

OBJECTIVE

This study aimed to determine whether multiple weight cycles in adulthood are an independent predictor of lower muscle mass and reduced strength, with potential implication for sarcopenia in adults with obesity.

METHODS

A total of 60 males and 147 females with obesity were included, with a mean BMI of 37.9 ± 6.0 kg/m² and a mean age of 52.6 ± 12.4 years. Muscle strength was evaluated with handgrip and appendicular skeletal muscle mass was measured with dual-energy x-ray absorptiometry.

RESULTS

Participants were categorized into the following three groups: non-weight cyclers, mild weight cyclers, and severe weight cyclers. From a binary logistic regression that considered muscle mass categories as a dependent variable and weight cycling categories, age, and sex as independent variables, severe weight cyclers showed a 3.8-times increased risk of low muscle mass (95% CI: 1.42-10.01). Considering handgrip strength categories as a dependent variable and weight cycling categories, age, sex, and BMI as independent variables, severe weight cycling was associated with an increased risk of low muscle mass (about 6.3 times, 95% CI: 1.96-20.59). Severe weight cyclers showed a 5.2-times greater risk of developing sarcopenia.

CONCLUSIONS

In adults with obesity, weight cycling is associated with lower muscle mass and strength and a greater likelihood of developing sarcopenic obesity.

The less weight loss due to modest food restriction drove more fat accumulation in striped hamsters refed with high-fat diet

Food restriction (FR) has been commonly used to decrease body fat, reducing the risk of overweight in humans and animals. However, the lost weight has been shown to be followed by overweight when food restriction ends. It remains uncertain whether the weight loss drives the overweight, or not. In the present study, striped hamsters were restricted by 15%, 30% and 40% of ad libitum food intake for 2 weeks, followed by high-fat refeeding for 6 weeks (FR15%-Re, FR30%-Re and FR40%-Re). The hamsters in FR15%, FR30% and FR40% groups decreased by 21.1%, 37.8% and 50.0% in fat mass (P < 0.01), and 16.8%, 42.8% and 53.4% in leptin levels (P < 0.01) compared with the hamsters fed ad libitum. The FR15%-Re, FR30%-Re and FR40%-Re groups showed 77.0%, 37.2% and 23.7% more body fat than ad libitum group (P < 0.01). The FR15%-Re group showed considerable decreases in gene expression of arcuate nucleus co-expressing proopiomelanocortin (POMC), cocaine - and amphetamineregulated transcript (CART) and the long isoform of leptin receptor (LepRb) in the hypothalamus and of several genes associated with fatty acid transport to mitochondria and β-oxidation in brown adipose tissue and liver. It suggests that less weight loss is likely to drive more fat accumulation when food restriction ends, in which the impaired function of LepRb, POMC and CART in the brain and fatty acid oxidation in brown adipose tissue and liver may be involved.

IMPACT OF WEIGHT LOSS TRAJECTORY FOLLOWING RANDOMIZATION TO BARIATRIC SURGERY ON LONG-TERM DIABETES GLYCEMIC AND CARDIOMETABOLIC PARAMETERS

Objective: It is unclear whether acute weight loss or the chronic trajectory of weight loss after bariatric surgery is associated with long-term type 2 diabetes mellitus (T2DM) glycemic improvement. This ancillary study of the Surgical Treatment and Medications Potentially Eradicate Diabetes Efficiently (STAMPEDE) trial aimed to answer this question. Methods: In STAMPEDE, 150 patients with T2DM were randomized to bariatric surgery, and 96 had 5-year follow-up. Data post-Roux-en-Y gastric bypass (RYGB, n = 49) and sleeve gastrectomy (SG, n = 47) were analyzed. We defined percent weight loss in the first year as negative percent decrease from baseline weight to lowest weight in the first year. Percent weight regain was positive percent change from lowest weight in the first year to fifth year. Weight change was then correlated with cardiometabolic (CM) and glycemic outcomes at 5 years using Spearman rank correlations and multivariate analysis. Results: In both RYGB and SG, less weight loss in the first year positively correlated with higher 5-year glycated hemoglobin (HbA1c) (RYGB, β = +0.13; P<.001 and SG, β = 0.14; P<.001). In SG, greater weight regain from nadir positively correlated with higher HbA1c (β = 0.06; P = .02), but not in RYGB. Reduced first-year weight loss was also correlated with increased 5-year triglycerides (β = 1.81; P = .01), but not systolic blood pressure. Weight regain did not correlate with CM outcomes. Conclusion: Acute weight loss may be more important for T2DM glycemic control following both RYGB and SG as compared with weight regain. Clinicians should aim to assist patients with achieving maximal weight loss in the first year post-op to maximize long-term health of patients. Abbreviations: BMI = body mass index; HbA1c = glycated hemoglobin; RYGB = Roux-en-Y gastric bypass; SBP = systolic blood pressure; SG = sleeve gastrectomy; STAMPEDE = Surgical Treatment and Medications Potentially Eradicate Diabetes Efficiently; T2DM = type 2 diabetes mellitus; TG = triglyceride.

The decline in muscle strength and muscle quality in relation to metabolic derangements in adult women with obesity

BACKGROUND & AIMS

The metabolic and functional characteristics related to sarcopenic obesity have not been thoroughly explored in the earlier stages of the aging process. The aim of the present study was to examine the phenotype of sarcopenic obesity, in terms of lean body mass, muscle strength and quality, in adult women with and without the Metabolic Syndrome (MetS), and its relationship with the features of myosteatosis.

METHODS

Study participants were enrolled at the Sapienza University, Rome, Italy. Body composition was assessed by DXA. The Handgrip strength test (HGST) was performed. HGST was normalized to arm lean mass to indicate muscle quality; intermuscular adipose tissue (IMAT) and intramyocellular lipid content (IMCL) were measured by magnetic resonance imaging and spectroscopy, as indicators of myosteatosis. Different indices of sarcopenia were calculated, based on appendicular lean mass (ALM, kg) divided by height squared, or weight. The NCEP-ATPIII criteria were used to diagnose the MetS. HOMA-IR was calculated. The physical activity level (PAL) was assessed through the IPAQ questionnaire.

RESULTS

54 women (age: 48 ± 14 years, BMI: 37.9 ± 5.4 kg/m²) were included. 54% had the MetS (metabolically unhealthy, MUO). HGST/arm lean mass was lower in MUO women than women without the MetS (6.3 ± 1.8 vs. 7.8 ± 1.6, p = 0.03). No differences emerged in terms of absolute ALM (kg) or other indices of sarcopenia (ALM/h² or ALM/weight) between metabolically healthy (MHO) vs. MUO women (p > 0.05). Muscle quality was negatively associated with HOMA-IR (p = 0.02), after adjustment for age, body fat, hs-CRP levels, and PAL. IMAT, but not IMCL, was significantly higher in obese women with the MetS compared to women without the MetS (p > 0.05). No association emerged between HGST/arm lean mass and IMAT or IMCL when HOMA-IR was included in the models.

CONCLUSION

Insulin resistance, and not sarcopenia or myosteatosis per se, was associated with muscle weakness, resulting in the phenotype of "dynapenic obesity" in middle-aged women with the metabolic syndrome.

Intermittent Dieting: Theoretical Considerations for the Athlete

Athletes utilise numerous strategies to reduce body weight or body fat prior to competition. The traditional approach requires continuous energy restriction (CER) for the entire weight loss phase (typically days to weeks). However, there is some suggestion that intermittent energy restriction (IER), which involves alternating periods of energy restriction with periods of greater energy intake (referred to as ‘refeeds’ or ‘diet breaks’) may result in superior weight loss outcomes than CER. This may be due to refeed periods causing transitory restoration of energy balance. Some studies indicate that intermittent periods of energy balance during energy restriction attenuate some of the adaptive responses that resist the continuation of weight and fat loss. While IER—like CER—is known to effectively reduce body fat in non-athletes, evidence for effectiveness of IER in athletic populations is lacking. This review provides theoretical considerations for successful body composition adjustment using IER, with discussion of how the limited existing evidence can be cautiously applied in athlete practice.