Weight loss composition is one-fourth fat-free mass: a critical review and critique of this widely cited rule

Strategies for minimizing muscle loss during use of incretin-mimetic drugs for treatment of obesity

The rapid and widespread clinical adoption of highly effective incretin-mimetic drugs (IMDs), particularly semaglutide and tirzepatide, for the treatment of obesity has outpaced the updating of clinical practice guidelines. Consequently, many patients may be at risk for adverse effects and uncertain long-term outcomes related to the use of these drugs. Of emerging concern is the loss of skeletal muscle mass and function that can accompany rapid substantial weight reduction; such losses can lead to reduced functional and metabolic health, weight cycling, compromised quality of life, and other adverse outcomes. Available evidence suggests that clinical trial participants receiving IMDs for the treatment of obesity lost 10% or more of their muscle mass during the 68- to 72-week interventions, approximately equivalent to 20 years of age-related muscle loss. The ability to maintain muscle mass during caloric restriction-induced weight reduction is influenced by two key factors: nutrition and physical exercise. Nutrition therapy should ensure adequate intake and absorption of high-quality protein and micronutrients, which may require the use of oral nutritional supplements. Additionally, concurrent physical activity, especially resistance training, has been shown to effectively minimize loss of muscle mass and function during weight reduction therapy. All patients receiving IMDs for obesity should participate in comprehensive treatment programs emphasizing adequate protein and micronutrient intakes, as well as resistance training, to preserve muscle mass and function, maximize the benefit of IMD therapy, and minimize potential risks.

Effects of Different Exercises Combined with Different Dietary Interventions on Body Composition: A Systematic Review and Network Meta-Analysis

BACKGROUND

Exercise and dietary interventions are essential for maintaining weight and reducing fat accumulation. With the growing popularity of various dietary strategies, evidence suggests that combining exercise with dietary interventions offers greater benefits than either approach alone. Consequently, this combined strategy has become a preferred method for many individuals aiming to maintain health. Calorie restriction, 5/2 intermittent fasting, time-restricted feeding, and the ketogenic diet are among the most popular dietary interventions today. Aerobic exercise, resistance training, and mixed exercise are the most widely practiced forms of physical activity. Exploring the best combinations of these approaches to determine which yields the most effective results is both meaningful and valuable. Despite this trend, a comparative analysis of the effects of different exercise and diet combinations is lacking. This study uses network meta-analysis to evaluate the impact of various combined interventions on body composition and to compare their efficacy.

METHODS

We systematically reviewed literature from database inception through May 2024, searching PubMed, Web of Science, Embase, and the Cochrane Library. The study was registered in PROSPERO under the title: "Effects of Exercise Combined with Different Dietary Interventions on Body Composition: A Systematic Review and Network Meta-Analysis" (identifier: CRD42024542184). Studies were meticulously selected based on specific inclusion and exclusion criteria (The included studies must be randomized controlled trials involving healthy adults aged 18 to 65 years. Articles were rigorously screened according to the specified inclusion and exclusion criteria.), and their risk of bias was assessed using the Cochrane risk of bias tool. Data were aggregated and analyzed using network meta-analysis, with intervention efficacy ranked by Surface Under the Cumulative Ranking (SUCRA) curves.

RESULTS

The network meta-analysis included 78 randomized controlled trials with 5219 participants, comparing the effects of four combined interventions: exercise with calorie restriction (CR+EX), exercise with time-restricted eating (TRF+EX), exercise with 5/2 intermittent fasting (5/2F+EX), and exercise with a ketogenic diet (KD+EX) on body composition. Intervention efficacy ranking was as follows: (1) Weight Reduction: CR+EX > KD+EX > TRF+EX > 5/2F+EX (Relative to CR+EX, the effect sizes of 5/2F+EX, TRF+EX and KD+EX are 2.94 (-3.64, 9.52); 2.37 (-0.40, 5.15); 1.80 (-1.75, 5.34)). (2) BMI: CR+EX > KD+EX > 5/2F+EX > TRF+EX (Relative to CR+EX, the effect sizes of 5/2F+EX, TRF+EX and KD+EX are 1.95 (-0.49, 4.39); 2.20 (1.08, 3.32); 1.23 (-0.26, 2.71)). (3) Body Fat Percentage: CR+EX > 5/2F+EX > TRF+EX > KD+EX (Relative to CR+EX, the effect sizes of 5/2F+EX, TRF+EX and KD+EX are 2.66 (-1.56, 6.89); 2.84 (0.56, 5.13); 3.14 (0.52, 5.75).). (4) Lean Body Mass in Male: CR+EX > TRF+EX > KD+EX (Relative to CR+EX, the effect sizes of TRF+EX and KD+EX are -1.60 (-6.98, 3.78); -2.76 (-7.93, 2.40)). (5) Lean Body Mass in Female: TRF+EX > CR+EX > 5/2F+EX > KD+EX (Relative to TRF+EX, the effect sizes of CR+EX, 5/2F+EX and KD+EX are -0.52 (-2.58, 1.55); -1.83 (-4.71, 1.04); -2.46 (-5.69,0.76).).

CONCLUSION

Calorie restriction combined with exercise emerged as the most effective strategy for reducing weight and fat percentage while maintaining lean body mass. For women, combining exercise with time-restricted eating proved optimal for preserving muscle mass. While combining exercise with a ketogenic diet effectively reduces weight, it is comparatively less effective at decreasing fat percentage and preserving lean body mass. Hence, the ketogenic diet combined with exercise is considered suboptimal.

Sarcopenic Obesity and Cardiovascular Disease: An Overlooked but High-Risk Syndrome

PURPOSE OF REVIEW

Sarcopenic obesity (SO), defined as the coexistence of excess fat mass and reduced skeletal muscle mass and strength, has emerged as an important cardiovascular risk factor, particularly in older adults. This review summarizes recent findings on the diagnosis, prevalence, health impacts, and treatment of SO.

RECENT FINDINGS

Growing evidence suggests SO exacerbates cardiometabolic risk and adverse health outcomes beyond either condition alone; however, the heterogeneity in diagnostic criteria and the observational nature of most studies prohibit the evaluation of a causal relationship. This is concerning given that SO is increasing with the aging population, although that is also difficult to assess accurately given wide-ranging prevalence estimates. A recent consensus definition proposed by the European Society for Clinical Nutrition and Metabolism and the European Association for the Study of Obesity provides a framework of standardized criteria to diagnose SO. Adopting uniform diagnostic criteria for SO will enable more accurate characterization of prevalence and cardiometabolic risk moving forward. Although current management revolves around diet for weight loss coupled with resistance training to mitigate further muscle loss, emerging pharmacologic therapies have shown promising results. As the global population ages, diagnosing and managing SO will become imperative to alleviate the cardiovascular burden.

Detecting sarcopenia in obesity: emerging new approaches

PURPOSE OF REVIEW

Sarcopenic obesity is a likely common, but certainly underestimated obesity phenotype, with an important negative clinical impact. Its definition and diagnosis have however remained elusive until recently.

RECENT FINDINGS

Substantial progress has been recently made in sarcopenic obesity diagnostic tools, with the first international consensus proposed by the European Society for Clinical Nutrition and Metabolism (ESPEN) and the European Association for the Study of Obesity (EASO). Very encouraging results emerge from initial implementation of the ESPEN-EASO algorithm. In addition, even more recent progress in global consensus on sarcopenia conceptual definition is likely to further enhance consistency in sarcopenic obesity identification. The latter Global Leadership Initiative on Sarcopenia (GLIS) initiative also adopted a new definition of muscle specific strength. Its inclusion in sarcopenia diagnostic constructs opens the possibility of its potential evaluation in sarcopenic obesity, also considering the emerging positive impact of obesity treatment and fat loss on muscle functional parameters.

SUMMARY

New consensus tools for sarcopenic obesity diagnosis are likely to improve awareness, understanding, identification and treatment of this under-recognized obesity phenotype.

Nutrition Practices of Lithuanian Elite International and National-level Male Bodybuilders in the Pre-competition Period

OBJECTIVES

To compare the pre-competition nutrition practices of Lithuanian elite international-level (IL) and national-level (NL) bodybuilders.

METHODS

Sixteen male bodybuilders (n=8 per group) were enrolled. The IL group comprised individuals achieving 1st to 4th place in the World and European Championships organized by the IFBB, whereas the NL group ranked between 1st and 6th place in the national championships. Body mass and diet data were obtained via a questionnaire. A repeated-measures ANOVA was performed using time as a within factor and group as a between factor.

RESULTS

Both groups experienced a reduction in body mass during the pre-competition phase (p<0.001), which was slower in the IL than in the NL group (p=0.048). Both groups exhibited a reduction in caloric (p<0.001), carbohydrate (p<0.001), and fat (p=0.006) intake relative to body mass, but not in protein intake. Nevertheless, the IL group had a higher intake of calories (p=0.015), protein (p<0.001), but not carbohydrates relative to body mass vs. the NL group.

CONCLUSIONS

The Lithuanian IL and NL bodybuilders both reduced calories by cutting fat and carbohydrates during pre-competition. The IL group maintained higher calorie and protein intake, resulting in similar body mass loss but at a slower rate than the NL group.

Changes in lean body mass with glucagon-like peptide-1-based therapies and mitigation strategies

Weight loss induced by glucagon-like peptide-1 receptor agonists (GLP-1RAs) and dual glucagon-like peptide-1 receptor (GLP-1R)/glucose-dependent insulinotropic polypeptide receptor agonists is coming closer to the magnitudes achieved with surgery. However, with greater weight loss there is concern about potential side effects on muscle quantity (mass), health and function. There is heterogeneity in the reported effects of GLP-1-based therapies on lean mass changes in clinical trials: in some studies, reductions in lean mass range between 40% and 60% as a proportion of total weight lost, while other studies show lean mass reductions of approximately 15% or less of total weight lost. There are several potential reasons underlying this heterogeneity, including population, drug-specific/molecular, and comorbidity effects. Furthermore, changes in lean mass may not always reflect changes in muscle mass as the former measure includes not only muscle but also organs, bone, fluids, and water in fat tissue. Based on contemporary evidence with the addition of magnetic resonance imaging-based studies, skeletal muscle changes with GLP-1RA treatments appear to be adaptive: reductions in muscle volume seem to be commensurate with what is expected given ageing, disease status, and weight loss achieved, and the improvement in insulin sensitivity and muscle fat infiltration likely contributes to an adaptive process with improved muscle quality, lowering the probability for loss in strength and function. Nevertheless, factors such as older age and severity of disease may influence the selection of appropriate candidates for these therapies due to risk of sarcopenia. To further improve muscle health during weight loss, several pharmacological treatments to maintain or improve muscle mass designed in combination with GLP-1-based therapies are under development. Future research on GLP-1-based and other therapies designed for weight loss should focus on more accurate and meaningful assessments of muscle mass, composition, as well as function, mobility or strength, to better define their impact on muscle health for the substantial number of patients who will likely be taking these medications well into the future.

Nutritional Considerations During Major Weight Loss Therapy: Focus on Optimal Protein and a Low-Carbohydrate Dietary Pattern

PURPOSE OF REVIEW

Considering the high prevalence of obesity and related metabolic impairments in the population, the unique role nutrition has in weight loss, reversing metabolic disorders, and maintaining health cannot be overstated. Normal weight and well-being are compatible with varying dietary patterns, but for the last half century there has been a strong emphasis on low-fat, low-saturated fat, high-carbohydrate based approaches. Whereas low-fat dietary patterns can be effective for a subset of individuals, we now have a population where the vast majority of adults have excess adiposity and some degree of metabolic impairment. We are also entering a new era with greater access to bariatric surgery and approval of anti-obesity medications (glucagon-like peptide-1 analogues) that produce substantial weight loss for many people, but there are concerns about disproportionate loss of lean mass and nutritional deficiencies.

RECENT FINDINGS

No matter the approach used to achieve major weight loss, careful attention to nutritional considerations is necessary. Here, we examine the recent findings regarding the importance of adequate protein to maintain lean mass, the rationale and evidence supporting low-carbohydrate and ketogenic dietary patterns, and the potential benefits of including exercise training in the context of major weight loss. While losing and sustaining weight loss has proven challenging, we are optimistic that application of emerging nutrition science, particularly personalized well-formulated low-carbohydrate dietary patterns that contain adequate protein (1.2 to 2.0 g per kilogram reference weight) and achieve the beneficial metabolic state of euketonemia (circulating ketones 0.5 to 5 mM), is a promising path for many individuals with excess adiposity.

Body Weight and Composition Changes in Geriatric Rehabilitation Are Dependent on Sarcopenia and Malnutrition: RESORT

OBJECTIVES

Body weight and muscle mass loss following an acute hospitalization in older patients may be influenced by malnutrition and sarcopenia among other factors. This study aimed to assess the changes in body weight and composition from admission to discharge and the geriatric variables associated with the changes in geriatric rehabilitation inpatients.

DESIGN

RESORT is an observational, longitudinal cohort.

SETTING AND PARTICIPANTS

Geriatric rehabilitation inpatients admitted to geriatric rehabilitation wards at the Royal Melbourne Hospital, Melbourne, Australia (N = 1006).

METHODS

Changes in body weight and body composition [fat mass (FM), appendicular lean mass (ALM)] from admission to discharge were analyzed using linear mixed models. Body mass index (BMI) categories, (risk of) malnutrition (Global Leadership Initiative on Malnutrition), sarcopenia (European Working Group on Sarcopenia in Older People), dependence in activities of daily living (ADL), multimorbidity, and cognitive impairment were tested as geriatric variables by which the changes in body weight and composition may differ.

RESULTS

A total of 1006 patients [median age: 83.2 (77.7-88.8) years, 58.5% female] were included. Body weight, FM (kg), and FM% decreased (0.30 kg, 0.43 kg, and 0.46%, respectively) and ALM (kg) and ALM% increased (0.17 kg and 0.33%, respectively) during geriatric rehabilitation. Body weight increased in patients with underweight; decreased in patients with normal/overweight, obesity, ADL dependence and in those without malnutrition and sarcopenia. ALM% and FM% decreased in patients with normal/overweight. ALM increased in patients without multimorbidity and in those with malnutrition and sarcopenia; ALM% increased in patients without multimorbidity and with sarcopenia.

CONCLUSIONS AND IMPLICATIONS

In geriatric rehabilitation, body weight increased in patients with underweight but decreased in patients with normal/overweight and obesity. ALM increased in patients with malnutrition and sarcopenia but not in patients without. This suggests the need for improved standard of care independent of patients' nutritional risk.

A low-calorie meal replacement improves body composition and metabolic parameters in shift workers with overweight and obesity: a randomized, controlled, parallel group trial

BACKGROUND

Shift work has been identified as a risk factor for several chronic health conditions including obesity. This study evaluated the impact of a low-calorie meal replacement (MR) as a dinner substitute on body composition and metabolic parameters in shift workers with overweight and obesity.

METHODS

An 8-week parallel, randomized controlled trial was conducted on overweight and obese shift workers in a large hospital. An intervention group (IG) (n = 25) was provided with a low-calorie MR shake (∼200 kcal) as a replacement for dinner, every day for 8 weeks, while the control group (CG) (n = 25) continued their habitual diet. Anthropometric measurements, body composition, biochemical, and lifestyle data were assessed at the first and last visits. Analyses were done per protocol (PP) and by intention to treat (ITT).

RESULTS

Over the study duration, both groups displayed moderate changes in anthropometric measurements and body composition, although these were not statistically significant according to the PP analysis. In the ITT analysis, apart from the hip circumference (HC), all other anthropometric parameters demonstrated significant group and time interactions, suggesting the advantageous effects of the meal replacement over the study period (P < 0.05). HDL and VLDL cholesterol measures showed significant main effects, influenced by both group (P = 0.031) and time (P = 0.050) respectively. The most pronounced dietary shift in the IG was a reduction in carbohydrate consumption and an increase in protein intake. Throughout the study, the meal replacement was well-tolerated, with no adverse events reported.

CONCLUSIONS

The meal replacement dietary intervention appears to offer beneficial health effects over time. Extended research is crucial to understand the broader implications of meal replacements across diverse populations.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR): ACTRN12622000231741. Registered on 09 February 2022. https://www.anzctr.org.au/ACTRN12622000231741.aspx .

Interindividual differences of dietary fat-inducible Mest in white adipose tissue of C57BL/6J mice are not heritable

OBJECTIVE

Differences in white adipose tissue (WAT) expression of mesoderm-specific transcript (Mest) in C57BL6/J mice fed a high-fat diet (HFD) are concomitant with and predictive for the development of obesity. However, the basis for differences in WAT Mest among mice is unknown. This study investigated whether HFD-inducible WAT Mest, as well as susceptibility to obesity, is transmissible from parents to offspring.

METHODS

WAT biopsies of mice fed an HFD for 2 weeks identified parents with low and high WAT Mest for breeding. Obesity phenotypes, WAT Mest, hepatic gene expression, and serum metabolites were determined in offspring fed an HFD for 2 weeks.

RESULTS

Offspring showed no heritability of obesity or WAT Mest phenotypes from parents but did show hepatic and serum metabolite changes consistent with their WAT Mest. Importantly, retired male breeders showed WAT Mest expression congruent with initial WAT biopsies even though HFD exposure occurred early in life.

CONCLUSIONS

Disparity of HFD-induced Mest in mice is not heritable but, rather, is reestablished during each generation and remains fixed from an early age to adulthood. Short-term HFD feeding reveals variation of WAT Mest expression within isogenic mice that is positively associated with the development of obesity.

The effect of obesity pharmacotherapy on body composition, including muscle mass

Obesity pharmacotherapy represents a promising approach to treating obesity and may provide benefits beyond weight loss alone. Maintaining or even increasing muscle mass during weight loss is important to overall health, metabolic function and weight loss maintenance. Drugs such as liraglutide, semaglutide, tirzepatide, and naltrexone/bupropion have shown significant weight loss effects, and emerging evidence suggests they may also have effects on body composition, particularly a positive influence on muscle mass. However, further research is needed to fully understand the mechanism of action of these drugs and their effects on muscle mass. Clinicians should consider these factors when developing an obesity treatment plan for an individual patient.

Sarcopenic obesity in older adults: a clinical overview

Sarcopenic obesity is characterized by a concurrent decline in muscle mass and function, along with increased adipose tissue. Sarcopenic obesity is a growing concern in older adults owing to significant health consequences, including implications for mortality, comorbidities and risk of developing geriatric syndromes. A 2022 consensus statement established a new definition and diagnostic criteria for sarcopenic obesity. The pathophysiology of this condition involves a complex interplay between muscle, adipose tissue, hormonal changes, inflammation, oxidative stress and lifestyle factors, among others. Sarcopenic obesity is treated with a range of management approaches, such as lifestyle interventions, exercise, nutrition and medical therapies. Emerging therapies that were developed for treating other conditions may be relevant to sarcopenic obesity, including novel pharmacological agents and personalized approaches such as precision medicine. In this Review, we synthesize the current knowledge of the clinical importance of sarcopenic obesity, its assessment and diagnosis, along with current and emerging management strategies.

Associations of change in body fat percentage with baseline body composition and diabetes remission after bariatric surgery

OBJECTIVE

The objective of this study was to determine the role of body fat percentage (BFP) changes in diabetes remission (DR) and the association between baseline body composition and its changes after bariatric surgery.

METHODS

We analyzed 203 patients with type 2 diabetes who underwent Roux-en-Y gastric bypass. Body composition was measured using a gold-standard-derived predictive equation and magnetic resonance imaging. Body composition changes were calculated as 100 × (baseline value - follow-up value)/baseline value. We verified the results in a laparoscopic sleeve gastrectomy cohort with 311 patients.

RESULTS

Compared with non-remission patients in the Roux-en-Y gastric bypass cohort, those who achieved DR showed a higher baseline fat-free mass index (FFMI) and experienced the most significant changes in BFP (p < 0.001). In comparative analyses, BFP changes were significantly better than BMI changes in identifying short- and long-term DR. Linear regression analysis identified FFMI as the most significant baseline variable correlated with BFP changes (p < 0.001). Baseline BMI was positively correlated with changes in BFP but negatively correlated with changes in FFMI. These findings were replicated in the laparoscopic sleeve gastrectomy cohort.

CONCLUSIONS

BFP changes determine DR after bariatric surgery, and baseline FFMI is crucial for BFP changes. A low initial BMI is associated with a smaller BFP reduction and greater FFMI loss after bariatric surgery.

A systematic review of the effect of semaglutide on lean mass: insights from clinical trials

INTRODUCTION

Semaglutide, a glucagon-like peptide-1 receptor agonist, is associated with significant weight loss, yet its impact on lean body mass remains insufficiently understood. This review investigates the effect of semaglutide on lean mass in the context of obesity management.

METHODOLOGY

This study investigates through different databases (PubMed, Elsevier, and Google Scholar) from 2016 for randomized control trials (RCTs) or observational studies that assessed the use of semaglutide in overweight or obese patients, regardless of whether they have type 2 diabetes or not. The studies compared semaglutide to a placebo or alternative medications.

RESULTS

Six studies with 1,541 overweight or obese adults were included, and significant weight reductions were observed primarily due to fat mass loss. While the lean mass remained stable in some cases, notable reductions ranging from almost 0% to 40% of total weight reduction were observed in others. Noteworthy decreases in lean mass were particularly evident in larger trials, yet the proportion of lean mass relative to total body mass increased, suggesting a positive overall outcome.

CONCLUSION

Semaglutide displays potential for weight loss primarily through fat mass reduction. However, concerns arise from notable reductions in lean mass, especially in trials with a larger number of patients.

Measuring Albuminuria in Individuals With Obesity: Pitfalls of the Urinary Albumin-Creatinine Ratio

An increased urinary albumin excretion rate is an important early risk factor for chronic kidney disease and other major outcomes and is usually measured using the urinary albumin-creatinine ratio (ACR). Obesity is highly prevalent in the general and chronic kidney disease populations and is an independent risk factor for moderately increased albuminuria (henceforth, moderate albuminuria). In this review, we describe how the ACR was developed and used to define moderate albuminuria. We then investigate how biases related to urinary creatinine excretion are introduced into the ACR measurement and how the use of the 30-mg/g threshold decreases the performance of the test in populations with higher muscle mass, with a primary focus on why and how this occurs in the obese population. The discussion then raises several strategies that can be used to mitigate such bias. This review provides a comprehensive overview of the medical literature on the uses and limitations of ACR in individuals with obesity and critically assesses related issues. It also raises into question the widely accepted 30-mg/g threshold as universally adequate for the diagnosis of moderate albuminuria. The implications of our review are relevant for clinicians, epidemiologists, and clinical trialists.

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.

Weight loss outcomes are generally worse for dogs and cats with class II obesity, defined as > 40% overweight

In pet dogs and cats, adiposity is most-often estimated clinically using a 9-category body condition score (BCS), with BCS 9 equating to ~ 40% overweight. Animals that are more overweight (> 40%) are seen in clinical practice but are not appropriately depicted by descriptions in the existing categories. To determine whether being > 40% overweight has clinical relevance, this study aimed to compare the outcomes of weight management in animals that were > 40% overweight with those < 40% overweight. Records of dogs and cats attending a specialist obesity care clinic, where adiposity is determined using dual-energy X-ray absorptiometry (DXA), were reviewed. Animals were assigned to two classes (class I ≤ 40% overweight: 118/398 [40%] dogs and 68/116 [59%] cats; class II, > 40% overweight: 180/398 [60%] dogs and 48/116 [41%] cats) based on DXA results, and weight loss outcomes were compared. Fewer class II dogs obesity completed weight management than class I dogs (P < 0.001), rate of weight loss was also slower (P = 0.012) and lean tissue loss greater (P < 0.001). Compared with class I, cats with class II obesity lost more weight (P = 0.048) albeit over a longer period (P = 0.043) leading to greater lean tissue loss (P = 0.004). Approximately half the pets presenting to a specialist clinic were have class II obesity (> 40% overweight), and some weight loss outcomes are worse for these animals.

Combined Exercise Training and Nutritional Interventions or Pharmacological Treatments to Improve Exercise Capacity and Body Composition in Chronic Obstructive Pulmonary Disease: A Narrative Review

Chronic obstructive pulmonary disease (COPD) is a chronic respiratory disease that is associated with significant morbidity, mortality, and healthcare costs. The burden of respiratory symptoms and airflow limitation can translate to reduced physical activity, in turn contributing to poor exercise capacity, muscle dysfunction, and body composition abnormalities. These extrapulmonary features of the disease are targeted during pulmonary rehabilitation, which provides patients with tailored therapies to improve the physical and emotional status. Patients with COPD can be divided into metabolic phenotypes, including cachectic, sarcopenic, normal weight, obese, and sarcopenic with hidden obesity. To date, there have been many studies performed investigating the individual effects of exercise training programs as well as nutritional and pharmacological treatments to improve exercise capacity and body composition in patients with COPD. However, little research is available investigating the combined effect of exercise training with nutritional or pharmacological treatments on these outcomes. Therefore, this review focuses on exploring the potential additional beneficial effects of combinations of exercise training and nutritional or pharmacological treatments to target exercise capacity and body composition in patients with COPD with different metabolic phenotypes.

The Effects of Sodium-Glucose Cotransporter 2 Inhibitors on Body Composition in Type 2 Diabetes Mellitus: A Narrative Review

Body composition is related to cardiometabolic disorders and is a major driver of the growing incidence of type 2 diabetes mellitus (T2DM). Altered fat distribution and decreased muscle mass are related to dysglycemia and impose adverse health-related outcomes in people with T2DM. Hence, improving body composition and maintaining muscle mass is crucial in T2DM. Sodium-glucose cotransporter 2 (SGLT2) inhibitors are novel glucose-lowering medications gaining popularity because of their cardiorenal-protective effects and weight-lowering characteristics. However, reports on myopathy secondary to SGLT2 inhibitor treatment raised a safety concern. The importance of maintaining muscle mass in people with T2DM necessitates further investigation to explore the impact of novel medications on body composition. In this review, we discussed current evidence on the impact of SGLT2 inhibitors on body composition in people with T2DM.

Intermittent fasting and bone health: a bone of contention?

Intermittent fasting (IF) is a promising strategy for weight loss and improving metabolic health, but its effects on bone health are less clear. This review aims to summarise and critically evaluate the preclinical and clinical evidence on IF regimens (the 5:2 diet, alternate-day fasting (ADF) and time-restricted eating (TRE)/time-restricted feeding and bone health outcomes. Animal studies have utilised IF alongside other dietary practices known to elicit detrimental effects on bone health and/or in models mimicking specific conditions; thus, findings from these studies are difficult to apply to humans. While limited in scope, observational studies suggest a link between some IF practices (e.g. breakfast omission) and compromised bone health, although lack of control for confounding factors makes these data difficult to interpret. Interventional studies suggest that TRE regimens practised up to 6 months do not adversely affect bone outcomes and may even slightly protect against bone loss during modest weight loss (< 5 % of baseline body weight). Most studies on ADF have shown no adverse effects on bone outcomes, while no studies on the ‘5–2’ diet have reported bone outcomes. Available interventional studies are limited by their short duration, small and diverse population samples, assessment of total body bone mass exclusively (by dual-energy X-ray absorptiometry) and inadequate control of factors that may affect bone outcomes, making the interpretation of existing data challenging. Further research is required to better characterise bone responses to various IF approaches using well-controlled protocols of sufficient duration, adequately powered to assess changes in bone outcomes and designed to include clinically relevant bone assessments.

Temporal trends in obesity defined by the relative fat mass (RFM) index among adults in the United States from 1999 to 2020: a population-based study

OBJECTIVES

The body mass index (BMI) largely underestimates excess body fat, suggesting that the prevalence of obesity could be underestimated. Biologically, women are known to have higher body fat than men. This study aimed to compare the temporal trends in general obesity by sex, ethnicity and age among adults in the USA using the relative fat mass (RFM), a validated surrogate for whole-body fat percentage and BMI.

DESIGN

Population-based study.

SETTING

US National Health and Nutrition Examination Survey, from 1999-2000 to 2017-March 2020.

PARTICIPANTS

A representative sample of adults 20-79 years in the USA.

MAIN OUTCOME MEASURES

Age-adjusted prevalence of general obesity. RFM-defined obesity was diagnosed using validated cut-offs to predict all-cause mortality: RFM≥40% for women and ≥30% for men. BMI-defined obesity was diagnosed using a cut-off of 30 kg/m2.

RESULTS

Analysis included data from 47 667 adults. Among women, RFM-defined obesity prevalence was 64.7% (95% CI 62.1% to 67.3%) in 2017-2020, a linear increase of 13.9 percentage points (95% CI 9.0% to 18.9%; p<0.001) relative to 1999-2000. In contrast, the prevalence of BMI-defined obesity was 42.2% (95% CI 39.4% to 45.0%) in 2017-2020. Among men, the corresponding RFM-defined obesity prevalence was 45.8% (95% CI 42.0% to 49.7%), a linear increase of 12.0 percentage points (95% CI 6.6% to 17.3%; p<0.001). In contrast, the prevalence of BMI-defined obesity was 42.0 (95% CI 37.8% to 46.3%). The highest prevalence of RFM-defined obesity across years was observed in older adults (60-79 years) and Mexican Americans, in women and men. Conversely, the highest prevalence of BMI-defined obesity across years was observed in middle-age (40-59 years) and older adults, and in African American women.

CONCLUSIONS

The use of a surrogate for whole-body fat percentage revealed a much higher prevalence of general obesity in the USA from 1999 to 2020, particularly among women, than that estimated using BMI, and detected a disproportionate higher prevalence of general obesity in older adults and Mexican Americans.

The importance of fat-free mass and constituent tissue-organs in the control of human appetite

PURPOSE OF REVIEW

Traditional models of human appetite focus on the contribution of adipose tissue and the gastrointestinal tract, both of which exert mainly inhibitory influences. The purpose of this review is to consider the biological factors that influence the drive to eat.

RECENT FINDINGS

Fat-free mass is positively associated with objectively measured meal size and daily energy intake. These findings have been replicated in multiple populations across the life-course in laboratory and free-living studies. Studies have shown that the effect of fat-free mass is statistically mediated by resting metabolic rate, suggesting that energy expenditure per se may influence energy intake. A recent MRI study has reported that fasting hunger was associated with high metabolic rate organ (heart, liver, brain, kidneys) and skeletal muscle mass. Integrating measures of body composition at the tissue-organ level and markers of their metabolic function with appetitive measures could provide novel insight into the mechanisms that influence appetite.

SUMMARY

These recent findings suggest that fat-free mass and resting metabolic rate are determinants of energy intake. Consideration of fat-free mass and energy expenditure as physiological sources of appetitive signals helps reconcile the mechanisms underpinning the inhibition of eating with those that drive eating.

Nutrition interventions for adults with dyslipidemia: A Clinical Perspective from the National Lipid Association

Lifestyle habits can have a profound impact on atherosclerotic cardiovascular disease (ASCVD) risk. The National Lipid Association previously published recommendations for lifestyle therapies to manage dyslipidemia. This Clinical Perspective provides an update with a focus on nutrition interventions for the three most common dyslipidemias in adults: 1) low-density lipoprotein cholesterol (LDL-C) elevation; 2) triglyceride (TG) elevation, including severe hypertriglyceridemia with chylomicronemia; and 3) combined dyslipidemia, with elevations in both LDL-C and TG levels. Lowering LDL-C and non-high-density lipoprotein cholesterol are the primary objectives for reducing ASCVD risk. With severe TG elevation (≥500 mg/dL), the primary objective is to prevent pancreatitis and ASCVD risk reduction is secondary. Nutrition interventions that lower LDL-C levels include reducing cholesterol-raising fatty acids and dietary cholesterol, as well as increasing intakes of unsaturated fatty acids, plant proteins, viscous fibers, and reducing adiposity for patients with overweight or obesity. Selected dietary supplements may be employed as dietary adjuncts. Nutrition interventions for all patients with elevated TG levels include restricting intakes of alcohol, added sugars, and refined starches. Additional lifestyle factors that reduce TG levels are participating in daily physical activity and reducing adiposity in patients with overweight or obesity. For patients with severe hypertriglyceridemia, an individualized approach is essential. Nutrition interventions for addressing concurrent elevations in LDL-C and TG include a combination of the strategies described for lowering LDL-C and TG. A multidisciplinary approach is recommended to facilitate success in making and sustaining dietary changes and the assistance of a registered dietitian nutritionist is highly recommended.

Body Composition in Late Midlife as a Predictor of Accelerated Age-associated Deficit-accumulation From Late Midlife into Old Age: A Longitudinal Birth Cohort Study

BACKGROUND

Body mass index (BMI) may not be an optimal predictor of frailty as its constituents, lean and fat mass, may have opposite associations with frailty.

METHODS

A linear mixed model analysis was performed in the Helsinki Birth Cohort Study (n = 2 000) spanning from 57 to 84 years. A 39-item frailty index (FI) was calculated on three occasions over 17 years. Body composition in late midlife included BMI, percent body fat (%BF), waist-to-hip ratio (WHR), lean mass index (LMI), and fat mass index (FMI).

RESULTS

Mean FI levels increased by 0.28%/year among men and by 0.34%/year among women. Among women, per each kg/m2 higher BMI and each unit higher %BF the increases in FI levels per year were 0.013 percentage points (PP) steeper (95% CI = 0.004, 0.023) and 0.009 PP steeper (95% CI = 0.002, 0.016) from late midlife into old age. Among men, per each 0.1-unit greater WHR the increase in FI levels was 0.074 PP steeper per year (95% CI = -0.0004, 0.148). Cross-sectionally, greater FMI and LMI in late midlife were associated with higher FI levels but the direction of the association regarding LMI changed after adjustment for FMI. The categories "high FMI and high LMI" and "high FMI and low LMI" showed the highest FI levels relative to the category "low FMI and low LMI".

CONCLUSIONS

In late midlife, greater adiposity (%BF) among women and abdominal obesity (WHR) among men may predispose to higher levels of frailty from late midlife into old age. Greater lean mass alone may be protective of frailty, but not in the presence of high fat mass.

Detrimental Changes in Health during Menopause: The Role of Physical Activity

Midlife women experience changes in cardiometabolic, physical, and psychosocial health during menopause that negatively impacts their overall quality of life. Factors that contribute to these increases in cardiometabolic risk include weight gain as well as increases in fat mass (particularly abdominal adiposity), insulin resistance, and vascular dysfunction. Other deleterious changes in physical health (e. g. reduced sleep health, bone density, and balance) as well as changes in psychosocial health (e. g. mood, anxiety, and depression) often coincide and are linked to these increases in cardiometabolic risk. Physical activity and exercise are important lifestyle components that have been demonstrated to improve cardiometabolic, physical, and psychosocial health, yet physical activity and exercise is known to decline during perimenopause and into the postmenopausal years. In this narrative review, we summarize these changes in overall health during menopause as well as how declining physical activity contributes to these changes. Additionally, we discuss how incorporating physical activity and exercise during menopause can potentially ameliorate health declines. We conclude that there exists a significant, positive impact of physical activity on cardiometabolic, physical, and psychological health among midlife women, particularly if undertaken during the perimenopausal and postmenopausal years.

Effects of ketogenic diet on health outcomes: an umbrella review of meta-analyses of randomized clinical trials

BACKGROUND

Systematic reviews and meta-analyses of randomized clinical trials (RCTs) have reported the benefits of ketogenic diets (KD) in various participants such as patients with epilepsy and adults with overweight or obesity. Nevertheless, there has been little synthesis of the strength and quality of this evidence in aggregate.

METHODS

To grade the evidence from published meta-analyses of RCTs that assessed the association of KD, ketogenic low-carbohydrate high-fat diet (K-LCHF), and very low-calorie KD (VLCKD) with health outcomes, PubMed, EMBASE, Epistemonikos, and Cochrane database of systematic reviews were searched up to February 15, 2023. Meta-analyses of RCTs of KD were included. Meta-analyses were re-performed using a random-effects model. The quality of evidence per association provided in meta-analyses was rated by the GRADE (Grading of Recommendations, Assessment, Development, and Evaluations) criteria as high, moderate, low, and very low.

RESULTS

We included 17 meta-analyses comprising 68 RCTs (median [interquartile range, IQR] sample size of 42 [20-104] participants and follow-up period of 13 [8-36] weeks) and 115 unique associations. There were 51 statistically significant associations (44%) of which four associations were supported by high-quality evidence (reduced triglyceride (n = 2), seizure frequency (n = 1) and increased low-density lipoprotein cholesterol (LDL-C) (n = 1)) and four associations supported by moderate-quality evidence (decrease in body weight, respiratory exchange ratio (RER), hemoglobin A_1c, and increased total cholesterol). The remaining associations were supported by very low (26 associations) to low (17 associations) quality evidence. In overweight or obese adults, VLCKD was significantly associated with improvement in anthropometric and cardiometabolic outcomes without worsening muscle mass, LDL-C, and total cholesterol. K-LCHF was associated with reduced body weight and body fat percentage, but also reduced muscle mass in healthy participants.

CONCLUSIONS

This umbrella review found beneficial associations of KD supported by moderate to high-quality evidence on seizure and several cardiometabolic parameters. However, KD was associated with a clinically meaningful increase in LDL-C. Clinical trials with long-term follow-up are warranted to investigate whether the short-term effects of KD will translate to beneficial effects on clinical outcomes such as cardiovascular events and mortality.

Monitoring body composition change for intervention studies with advancing 3D optical imaging technology in comparison to dual-energy X-ray absorptiometry

BACKGROUND

Recent 3-dimensional optical (3DO) imaging advancements have provided more accessible, affordable, and self-operating opportunities for assessing body composition. 3DO is accurate and precise in clinical measures made by DXA. However, the sensitivity for monitoring body composition change over time with 3DO body shape imaging is unknown.

OBJECTIVES

This study aimed to evaluate the ability of 3DO in monitoring body composition changes across multiple intervention studies.

METHODS

A retrospective analysis was performed using intervention studies on healthy adults that were complimentary to the cross-sectional study, Shape Up! Adults. Each participant received a DXA (Hologic Discovery/A system) and 3DO (Fit3D ProScanner) scan at the baseline and follow-up. 3DO meshes were digitally registered and reposed using Meshcapade to standardize the vertices and pose. Using an established statistical shape model, each 3DO mesh was transformed into principal components, which were used to predict whole-body and regional body composition values using published equations. Body composition changes (follow-up minus the baseline) were compared with those of DXA using a linear regression analysis.

RESULTS

The analysis included 133 participants (45 females) in 6 studies. The mean (SD) length of follow-up was 13 (5) wk (range: 3-23 wk). Agreement between 3DO and DXA (R2) for changes in total FM, total FFM, and appendicular lean mass were 0.86, 0.73, and 0.70, with root mean squared errors (RMSEs) of 1.98 kg, 1.58 kg, and 0.37 kg, in females and 0.75, 0.75, and 0.52 with RMSEs of 2.31 kg, 1.77 kg, and 0.52 kg, in males, respectively. Further adjustment with demographic descriptors improved the 3DO change agreement to changes observed with DXA.

CONCLUSIONS

Compared with DXA, 3DO was highly sensitive in detecting body shape changes over time. The 3DO method was sensitive enough to detect even small changes in body composition during intervention studies. The safety and accessibility of 3DO allows users to self-monitor on a frequent basis throughout interventions. This trial was registered at clinicaltrials.gov as NCT03637855 (Shape Up! Adults; https://clinicaltrials.gov/ct2/show/NCT03637855); NCT03394664 (Macronutrients and Body Fat Accumulation: A Mechanistic Feeding Study; https://clinicaltrials.gov/ct2/show/NCT03394664); NCT03771417 (Resistance Exercise and Low-Intensity Physical Activity Breaks in Sedentary Time to Improve Muscle and Cardiometabolic Health; https://clinicaltrials.gov/ct2/show/NCT03771417); NCT03393195 (Time Restricted Eating on Weight Loss; https://clinicaltrials.gov/ct2/show/NCT03393195), and NCT04120363 (Trial of Testosterone Undecanoate for Optimizing Performance During Military Operations; https://clinicaltrials.gov/ct2/show/NCT04120363).

An Intervention of Four Weeks of Time-Restricted Eating (16/8) in Male Long-Distance Runners Does Not Affect Cardiometabolic Risk Factors

Timing of nutrient intake for athletes may affect exercise performance and cardiometabolic factors. Our objective was to examine the effect of time-restricted eating (TRE) on cardiometabolic health. Using a cross-over study design, 15 endurance-trained male runners were randomized to either a normal dietary pattern (ND) first (12 h eating/fasting times) followed by time-restricted eating (TRE) pattern (16 h fast; 8 h eating) or the reverse, with a 4-week washout period between interventions. Body composition, resting energy expenditure, blood pressure and serum insulin, glucose and lipids were measured using standard laboratory methods. Exercise training and dietary intake (calories and macronutrients) were similar across interventions. No significant differences were observed in resting energy expenditure, markers of insulin resistance, serum lipids or blood pressure. Body composition did change significantly (p < 0.05) with whole body fat mass (-0.8 ± 1.3 kg with TRE vs. +0.1 ± 4.3 kg with ND), leg fat mass (-0.3 ± 0.5 kg with TRE vs. +0.1 ± 0.4 kg with ND), and percent body fat (-1.0 ± 1.5% with TRE vs. +0.1 ± 1.3% with ND) declining more in the TRE intervention, with no change in fat-free mass. This study is one of a few to investigate the effects of an isocaloric 16/8 TRE eating pattern in trained endurance athletes and confirms no change in cardiometabolic risk factors. In conclusion, TRE is not detrimental to cardiometabolic health in endurance-trained male runners but could be beneficial on exercise performance by reducing fat mass.

The 13C-bicarbonate technique as a tool for measurement of energy expenditure in overweight dogs undergoing body weight reduction and the effect of different dietary composition

Changes in body size and composition, i.e., body weight (BW) gain or loss, affect the daily energy expenditure (EE). To ensure an appropriate BW reduction and to find an efficient strategy to reduce and maintain a target BW, regular evaluations and adjustments of energy allowance are important. This study aimed to provide a detailed knowledge about the possible changes in resting EE using the oral 13C-bicarbonate technique (o13CBT) as a research tool in 16 overweight pet dogs undergoing BW reduction. Dietary composition (i.e., in % of dry matter [DM] being a high protein [33.3], low fat [9.6], and high crude fiber [18.0] diet [LFHFibre], and a high protein [37.9], high fat [52.0], carbohydrate-free diet [HFat]) during 16 wk of energy restriction were evaluated regarding effects on resting EE, rate of BW reduction, body composition, and plasma concentrations of metabolic hormones involved in energy metabolism and appetite regulation. The mean BW loss was higher (P < 0.05) for the dogs fed the LFHFibre diet (1.1%/wk) than that for dogs fed the HFat diet (0.8%/wk), but the total BW reduction of 14.6% and 12.0% of initial BW did not differ significantly (P > 0.05). Resting EE was lower (P < 0.02) after the BW reduction; 414 kJ (99 kcal)/kg BW0.75/d at the start (week 0) and 326 kJ (78 kcal)/kg BW0.75/d at the end (week 16) of the study. The BW reduction in both groups (P > 0.05) consisted of both fat mass (FM) and fat-free mass (FFM). Energy expenditure, calculated in relation to amount of FFM, was not significantly (P > 0.05) affected by BW reduction. Dietary composition did not significantly affect (P > 0.05) plasma concentrations of insulin, leptin, and ghrelin, and no effect (P > 0.05) of BW reduction was observed on hormone concentrations. In conclusion, the o13CBT proved to be a useful research method for studying short-term EE in overweight dogs. Even though all dogs lost BW, most dogs were still overweight at the end of the study. Due to a high individual variation among dogs, a longer experimental period with a larger sample size would be desirable.

Understanding sarcopenic obesity in young adults in clinical practice: a review of three unsolved questions

INTRODUCTION

Our aim was to summarize the available literature on three yet unsolved questions, namely: 1) the dilemma surrounding definition of sarcopenic obesity (SO), especially in young adults; 2) the potential impact of this phenotype on weight-loss programme outcomes; and 3) the strategies for optimum management (prevention/treatment) of SO in clinical practice.

EVIDENCE ACQUISITION

A literature review using the PubMed/Medline database was conducted, and data were summarized based on a narrative approach.

EVIDENCE SYNTHESIS

Firstly, SO can be screened by the 30-sec sit-to-stand test; ≤25 and ≤21; and confirmed by the ratio of (appendicular lean mass/Body Mass Index) ≤0.789 and 0.512 in males and females, respectively. Secondly, SO is associated with impaired physical fitness, reduced resting energy expenditure and an inactive lifestyle, that seems to negatively impact on weight-management outcomes, namely increasing early dropout and difficulty in maintaining weight loss in the long term. Finally, prevention/treatment of SO in young adults must be realized through tailored lifestyle intervention (diet+exercise) to preserve and improve strength and muscle mass, even where weight loss is necessary.

CONCLUSIONS

Our findings have clinical implications since they may help in screening, managing and improving the weight-loss outcomes of patients with SO in clinical settings.

Wasting syndrome and associated factors in hospitalized older people

Wasting syndrome (WS) is characterized by clinically important unintentional weight loss >5 % in six to 12 months. This syndrome is responsible for a significant portion of hospitalizations throughout the world and is an important indicator of serious diseases, especially in individuals with 60 years of age or older. The aim of the present study was to investigate WS and associated factors in hospitalized older people. An observational cross-sectional study was developed at a university hospital in Brazil with male and female patients ≥60 years of age. WS was considered in the occurrence of unintentional weight loss of 10 % in 12 months, 7.5 % in six months or >5 % in three months. Data were collected on sociodemographic, clinical, lifestyle, nutritional and biochemical characteristics. This study received approval from the local institutional review board and all participants signed a statement of informed consent. The sample was composed of 178 older people with a mean age of 70.0 ± 8.0 years. The prevalence of WS was 45.5 %. WS was associated with the following clinical variables: conservative CKD (p = 0.007), dysphagia (p = 0.035), dementia (p = 0.017), anorexia (p < 0.001), fatigue (p = 0.001), functional dependence (measured using the Barthel Index) (p = 0.001) and medications that cause malabsorption (p = 0.020); the following nutritional variables: body mass index (p < 0.001), low calf circumference (p < 0.001), low muscle strength (p = 0.001), low muscle mass (p < 0.001) and undernourishment or risk of malnutrition (evaluated using the Mini Nutritional Assessment); and the following biochemical variables: high CRP (p = 0.027), hypoalbuminemia (p = 0.005) and anemia (p < 0.001). The prevalence of WS was high among the hospitalized older people in the present sample and was associated with clinical and biochemical aspects as well as all nutritional variables analyzed. In contrast, lifestyle and sociodemographic characteristics were not associated with wasting syndrome.

Musculoskeletal effects of obesity and bariatric surgery – a narrative review

Obesity affects several areas of the human body, leading to increased morbidity and mortality and the likelihood of other diseases, such as type 2 diabetes mellitus, cardiovascular diseases and musculoskeletal disorders. These conditions predispose to bone fractures and sarcopenic obesity, defined by the presence of an obesity-associated decrease in muscle mass and strength. Both bone fragility and sarcopenic obesity disease are consequences of several factors, such as a low degree of chronic inflammation, insulin resistance, hormonal changes, nutritional deficiencies, ectopic fat deposits and sedentary lifestyle. The diagnosis of obesity-related musculoskeletal disorders is limited by the lack of sarcopenia criteria and lower accuracy of bone mineral density measurement by dual-energy X-ray absorptiometry in overweight people. Reducing body weight provides undeniable benefits to this population, however treating cases of severe obesity with bariatric surgery can cause even greater damage to bone and muscle health, especially in the long term. The mechanisms involved in this process are not yet fully understood, but factors related to nutrient malabsorption and mechanical discharge as well as changes in gut hormones, adipokines and bone marrow adiposity should be taken into account. Depending on the surgical technique performed, greater musculoskeletal damage may occur, especially in cases of malabsorptive surgeries such as Roux-en-Y gastric bypass, when compared to restrictive techniques such as sleeve gastrectomy. This difference is probably due to greater weight loss, nutrient malabsorption and important hormonal changes that occur as a consequence of the diversion of intestinal transit and loss of greater absorptive surface. Thus, people undergoing bariatric procedures, especially malabsorptive ones, should have their musculoskeletal health supervised to allow early diagnosis and appropriate therapeutic interventions to prevent osteoporotic fractures and preserve the functionality of the skeletal muscles.

Mediterranean Diet versus Very Low-Calorie Ketogenic Diet: Effects of Reaching 5% Body Weight Loss on Body Composition in Subjects with Overweight and with Obesity-A Cohort Study

The best nutritional strategy to fight the rise in obesity remains a debated issue. The Mediterranean diet (MD) and the Very Low-Calorie Ketogenic diet (VLCKD) are effective at helping people lose body weight (BW) and fat mass (FM) while preserving fat-free mass (FFM). This study aimed to evaluate the time these two diets took to reach a loss of 5% of the initial BW and how body composition was affected. We randomized 268 subjects with obesity or overweight in two arms, MD and VLCKD, for a maximum of 3 months or until they reached 5% BW loss. This result was achieved after one month of VLCKD and 3 months of MD. Both diets were effective in terms of BW (p < 0.0001) and FM loss (p < 0.0001), but the MD reached a higher reduction in both waist circumference (p = 0.0010) and FM (p = 0.0006) and a greater increase in total body water (p = 0.0017) and FFM (p = 0.0373) than VLCKD. The population was also stratified according to gender, age, and BMI. These two nutritional protocols are both effective in improving anthropometrical parameters and body composition, but they take different time spans to reach the goal. Therefore, professionals should evaluate which is the most suitable according to each patient's health status.

Are methods of estimating fat-free mass loss with energy-restricted diets accurate?

BACKGROUND/OBJECTIVES

Fat-free mass (FFM) often serves as a body composition outcome variable in weight loss studies. An important assumption is that the proportions of components that make up FFM remain stable following weight loss; some body composition models rely on these "constants". This exploratory study examined key FFM component proportions before and following weight loss in two studies of participants with overweight and obesity.

SUBJECTS/METHODS

201 men and women consumed calorie-restricted moderate- or very-low carbohydrate diets leading to 10-18% weight loss in 9-15 weeks. Measured total body fat, lean mass, bone mineral, total body water (TBW), and body weight at baseline and follow-up were used to derive FFM and its chemical proportions using a four-component model.

RESULTS

A consistent finding in both studies was a non-significant reduction in bone mineral and a corresponding increase (p < 0.001) in bone mineral/FFM; FFM density increased significantly in one group of women and in all four participant groups combined (both, p < 0.05). FFM hydration (TBW/FFM) increased in all groups of men and women, one significantly (p < 0.01), and in the combined sample (borderline, p < 0.10). The proportion of FFM as protein decreased across all groups, two significantly (p < 0.05-0.01) and in the combined sample (p < 0.05).

CONCLUSION

FFM relative proportions of chemical components may not be identical before and after short-term weight loss, an observation impacting some widely used body composition models and methods. Caution is thus needed when applying FFM as a safety signal or to index metabolic evaluations in clinical trials when these body composition approaches are used.

Implication of diet and exercise on the management of age‐related sarcopenic obesity in Asians

The incidence of sarcopenic obesity among adults aged ≥65 years is rising worldwide. Sarcopenic obesity is a high‐risk geriatric syndrome defined as a gain in the amount of adipose tissue along with the age‐related loss of muscle mass and strength or physical performance. Sarcopenic obesity is associated with increased risks of falls, physical limitations, cardiovascular diseases, metabolic diseases, and/or mortality. Thus, the identification of preventive and treatment strategies against sarcopenic obesity is important for healthy aging. Diet and exercise are the reasons for the development of sarcopenic obesity and are key targets in its prevention and treatment. Regarding weight reduction alone, it is most effective to maintain a negative energy balance with dietary calorie restriction and aerobic exercise. However, it is important to preserve skeletal muscle mass while reducing fat mass. Resistance exercise and appropriate protein supply are the main ways of preserving skeletal muscle mass, as well as muscle function. Therefore, in order to improve sarcopenic obesity, a complex treatment strategy is needed to limit energy ingestion with proper nutrition and to increase multimodal exercises. In this review, we focus on recently updated interventions for diet and exercise and potential future management strategies for Asian individuals with aging‐related sarcopenic obesity. Geriatr Gerontol Int 2022; 22: 695–704.

Effects of Intermittent Energy Restriction Alone and in Combination with Sprint Interval Training on Body Composition and Cardiometabolic Biomarkers in Individuals with Overweight and Obesity

The popularity of intermittent fasting (IF) and high intensity (sprint) interval training (SIT) has increased in recent years amongst the general public due to their purported health benefits and feasibility of incorporation into daily life. The number of scientific studies investigating these strategies has also increased, however, very few have examined the combined effects, especially on body composition and cardiometabolic biomarkers, which is the primary aim of this investigation. A total of thirty-four male and female participants (age: 35.4 ± 8.4 y, body mass index (BMI): 31.3 ± 3.5 kg/m2, aerobic capacity (VO2peak) 27.7 ± 7.0 mL·kg−1·min−1) were randomized into one of three 16-week interventions: (1) 5:2 IF (2 non-consecutive days of fasting per week, 5 days on ad libitum eating), (2) supervised SIT (3 bouts per week of 20s cycling at 150% VO2peak followed by 40 s of active rest, total 10 min duration), and (3) a combination of both interventions. Body composition, haemodynamic and VO2peak were measured at 0, 8 and 16 weeks. Blood samples were also taken and analysed for lipid profiles and markers of glucose regulation. Both IF and IF/SIT significantly decreased body weight, fat mass and visceral fat compared to SIT only (p < 0.05), with no significant differences between diet and diet + exercise combined. The effects of diet and/or exercise on cardiometabolic biomarkers were mixed. Only exercise alone or with IF significantly increased cardiorespiratory fitness. The results suggest that energy restriction was the main driver of body composition enhancement, with little effect from the low volume SIT. Conversely, to achieve benefits in cardiorespiratory fitness, exercise is required.

Pitfalls and pearls with drug dosing in the critically ill obese patient: 10 statements to guide ICU practitioners

Obesity is highly prevalent in ICU patients presenting a number of challenges, one of which is drug dosing. There are limited high-quality data describing drug dosing in obesity, which can lead to dosing strategies that are suboptimal. For example, inappropriately using the wrong weight for weight-based dosing can lead to supratherapeutic drug concentrations and an adverse drug event or subtherapeutic drug concentrations and treatment failure. A generalized framework for decision making specific for obese patients is available that describes a step-by-step approach for constructing dosing regimens. This manuscript will build on that framework by providing pitfalls and pearls for clinicians to consider when making dosing decisions in critically ill patients with severe obesity.

Body Composition Differences Between Excess Weight Loss ≥ 50% and < 50% at 12 Months Following Bariatric Surgery

Background

The relationship between weight loss and body composition is undefined after bariatric surgery. The objective of this study was to compare body composition changes in patients with excess weight loss ≥ 50% (EWL ≥ 50) and < 50% at 12 months post-operatively (EWL < 50).

Methods

A prospective cohort study was completed on patients undergoing bariatric surgery at two tertiary hospitals between 2017 and 2021. Body composition was measured with dual-energy X-ray absorptiometry immediately before surgery, and at 1, 6, and 12 months post-operatively. Body mass index (BMI), fat mass (FM), lean body mass (LBM), and skeletal muscle index (SMI) trajectories were analysed between patients with EWL ≥ 50% and EWL < 50%.

Results

Thirty-seven patients were included in this series (EWL ≥ 50% n = 25, EWL < 50% n = 12), comprising of both primary and revisional bariatric surgery cases, undergoing a sleeve gastrectomy (62.2%), Roux-en-Y gastric bypass (32.4%), or one anastomosis gastric bypass (5.4%). The EWL ≥ 50% group demonstrated a more optimal mean FM-to-LBM loss ratio than the EWL < 50% group. EWL ≥ 50% patients lost 2.0 kg more FM than EWL < 50% patients for each 1 kg of LBM lost. EWL ≥ 50% was also associated with an increase in mean SMI% over 12 months (5.5 vs. 2.4%; p < 0.0009). Across the whole cohort, the first month after surgery accounted for 67.4% of the total LBM reduction that occurred during the 12-month post-operative period.

Conclusion

This data suggests EWL ≥ 50% is associated with a more optimal body composition outcome than EWL < 50%. LBM reduction occurs predominantly in the early post-operative period.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s11695-022-06128-3.

Prevalence of low skeletal muscle mass following bariatric surgery

BACKGROUND AND AIMS

Evidence on the occurrence of low skeletal muscle mass (low-SMM) following bariatric surgery (BS) as well as on the impact of low-SMM antedating BS on post-surgical body composition (BC) are scant. In this context, we aimed to prospectively evaluate the prevalence of low-SMM prior to and up to 5 years after BS, and to evaluate pre-surgical low-SMM as an independent risk factor for the presence of low-SMM after BS.

METHODS

Retrospective analysis of prospectively collected database. BC was assessed by bioelectrical impedance analysis (BIA). A BIA-based formula was used to calculate skeletal muscle mass (SMM). Class I and class II low-SMM were defined respectively as a SMM index (SMMI = SMM/height²) value between -1 and -2, or > -2 standard deviations from the gender-specific regression line of the BMI versus the SMMI relationship in our reference group.

RESULTS

A total 952 subjects were included, with BC being available for 877 (92%) subjects at 12 months and for 576 subjects (60%) at 60 months after BS. Prior to surgery, and at 12-, or at 60-months after surgery, class I and class II low-SMM was ascertained respectively in 15.6% and 4.6%, 5.3% and 1.4%, and 16.6% and 6.3% of the study participants. Logistic regression analysis showed that the occurrence of low-SMM at 12- and 60-months follow-up, was independently predicted not only by age at the time of surgery [respectively, HR: 1.052 (95% CI 1.020-1.084), p = 0.001; and 1.042 (95% CI 1.019-1.066); p < 0.001] but also by the presence of low-SMM prior to surgery [respectively, HR: 10.717 (95% CI 5.771-19.904), p < 0.001; and 5.718 (95% CI 3.572-9.153); p < 0.001].

CONCLUSIONS

Our data suggest that a low-SMM phenotype occurs not only in obesity surgery candidates but also after BS, and that low-SMM prior to surgery is an important risk factor for low-SMM throughout post-surgical follow-up.

Clinical application of intermittent fasting for weight loss: progress and future directions

Intermittent fasting diets have become very popular in the past few years, as they can produce clinically significant weight loss. These diets can be defined, in the simplest of terms, as periods of fasting alternating with periods of eating. The most studied forms of intermittent fasting include: alternate day fasting (0-500 kcal per 'fast day' alternating with ad libitum intake on 'feast days'); the 5:2 diet (two fast days and five feast days per week) and time-restricted eating (only eating within a prescribed window of time each day). Despite the recent surge in the popularity of fasting, only a few studies have examined the health benefits of these diets in humans. The goal of this Review is to summarize these preliminary findings and give insights into the effects of intermittent fasting on body weight and risk factors for cardiometabolic diseases in humans. This Review also assesses the safety of these regimens, and offers some practical advice for how to incorporate intermittent fasting diets into everyday life. Recommendations for future research are also presented.

Association between self-reported body mass index and active life expectancy in a large community-dwelling sample of older U.S. adults

Background

Obesity may have a protective effect (greater survival) in older adults, a finding known as the “obesity paradox.” This study examined the association between self-reported body mass index (BMI) and active life expectancy (ALE) among older U.S. adults.

Methods

Using the Medicare Health Outcomes Survey Cohort 15 (2012 baseline, 2014 follow-up), we estimated life expectancy and ALE by participants’ baseline BMI and age using multi-state models. A participant was classified as in an active state if this person reported having no difficulty for any of these six activities of daily living (ADLs).

Results

Small differences in life expectancy were noted among persons in normal weight (BMI 18.5–24.9 kg/m²), overweight (BMI 25–29.9 kg/m²), and obesity ranges (BMI 30 kg/m² and higher). However, persons with obesity had a significantly lower ALE. ALE at age 65 was 11.1 (11.0–11.2) years for persons with obesity, 1.2 (1.1–1.3) years less than that for the normal weight and overweight persons (12.3 years for both, 12.2–12.4). Persons with class III obesity had a significantly lower life expectancy and ALE than normal weight persons. Although persons with class I or II obesity had a similar life expectancy as normal weight persons, they have a shorter ALE.

Conclusions

Although older adults with obesity have a similar life expectancy as normal weight persons, they have a significantly shorter ALE. Given the complex relationship of BMI and ALE, a “one size fits all” approach to weight management is not advisable.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-022-03021-7.

Stimulated Insulin Secretion Predicts Changes in Body Composition Following Weight Loss in Adults with High BMI

BACKGROUND

The aim of obesity treatment is to promote loss of fat relative to lean mass. However, body composition changes with calorie restriction differ among individuals.

OBJECTIVES

The goal of this study was to test the hypothesis that insulin secretion predicts body composition changes among young and middle-age adults with high BMI (in kg/m2) following major weight loss.

METHODS

Exploratory analyses were conducted with pre-randomization data from 2 large feeding trials: the Framingham, Boston, Bloomington, Birmingham, and Baylor study (FB4; n = 82, 43.9% women, BMI ≥27) and the Framingham State Food Study [(FS)2; n = 161, 69.6% women, BMI ≥25]. Participants in the 2 trials consumed calorie-restricted moderate-carbohydrate or very-low-carbohydrate diets to produce 12-18% weight loss in ∼14 wk or 10-14% in ∼10 wk, respectively. We determined insulin concentration 30 min after a 75-g oral glucose load (insulin-30) as a measure of insulin secretion and HOMA-IR as a measure of insulin resistance at baseline. Body composition was determined by DXA at baseline and post-weight loss. Associations were analyzed using general linear models with adjustment for covariates.

RESULTS

In FB4, higher insulin-30 was associated with a smaller decrease in fat mass (0.441 kg per 100 μIU/mL increment in baseline insulin-30; P = 0.005; -1.20-kg mean difference between the first compared with the fifth group of insulin-30) and a larger decrease in lean mass (-0.465 kg per 100 μIU/mL; P = 0.004; 1.27-kg difference). Participants with higher insulin-30 lost a smaller proportion of weight loss as fat (-3.37% per 100 μIU/mL; P = 0.003; 9.20% difference). Greater HOMA-IR was also significantly associated with adverse body composition changes. Results from (FS)2 were qualitatively similar but of a smaller magnitude.

CONCLUSIONS

Baseline insulin dynamics predict substantial individual differences in body composition following weight loss. These findings may inform understanding of the pathophysiological basis for weight regain and the design of more effective obesity treatment. Registered at clinicaltrials.gov as NCT03394664 and NCT02068885.

Focus on Nutritional Aspects of Sarcopenia in Diabetes: Current Evidence and Remarks for Future Research

Sarcopenia has been defined as a progressive and generalized loss of muscle mass that can be observed after the age of 40 years, with a rate of deterioration of about 8% every ten years up to 70 years, and 15-25% thereafter [...].

Changes in Body Composition in Older Adults after a Technology-Based Weight Loss Intervention

We conducted a post-hoc analysis of a pre/post, single-arm, non-randomized, multicomponent weight loss intervention in older adults. Fifty-three older adults aged ≥65 with a body mass index ≥ 30 kg/m2 were recruited to participate in a six-month, remote monitoring and video-conferencing delivered, prescriptive intervention consisting of individual and group-led registered dietitian nutrition and physical therapy sessions. We assessed weight, height, and body composition using a SECA 514 bioelectrical impedance analyzer. Mean age was 72.9±3.9 years (70% female) and all had ≥2 chronic conditions. Of those with complete data (n=30), we observed a 4.6±3.5kg loss in weight, 6.1±14.3kg (1.9%) loss in fat mass, and 0.78±1.69L loss in visceral fat (all p<0.05). Fat-free mass (-3.4kg±6.8, p=0.19), appendicular lean mass (-0.25±1.83, p=0.22), and grip strength (+3.46±7.89, p=0.56) did not significantly change. These variables were preserved after stratifying by 5% weight loss. Our intervention led to significant body and visceral fat loss while maintaining fat-free and appendicular lean muscle mass.

Association between cognitive performance and sarcopenic obesity in older adults with Alzheimer's disease

Sarcopenic obesity (SO), the co-occurrence of sarcopenia and obesity, is associated with functional loss, frailty, and incapacity in older adults. Recently, SO was associated with reduced cognitive performance in adults. However, no SO studies have been done with older adults with Alzheimer's disease (AD).

Objective

The objective of this study was to verify the occurrence of SO and associated factors in 43 older adults with AD.

Methods

We applied the Mini-Mental State Examination (MMSE) and Clinical Dementia Rating (CDR). SO was verified by using dual-emission X-ray absorptiometry.

Results

We found five women with SO. Women had higher body fat and lower muscle mass compared with men. There was a significant relationship between body fat and cognitive performance only in men (r=0.65; p<0.01) adjusted by age and education. Men with obesity and aged >75 years had better cognitive performance compared with non-obese men aged <75 years (p=0.010) and women with obesity aged >75 years (p=0.033).

Conclusions

Women with AD had higher body fat and lower muscle mass than men. SO occurs in older women with AD. Men with higher body fat showed better cognitive performance, independent of age and education.

Lessons from bariatric surgery: Can increased GLP-1 enhance vascular repair during cardiometabolic-based chronic disease?

Type 2 diabetes (T2D) and obesity represent entangled pandemics that accelerate the development of cardiovascular disease (CVD). Given the immense burden of CVD in society, non-invasive prevention and treatment strategies to promote cardiovascular health are desperately needed. During T2D and obesity, chronic dysglycemia and abnormal adiposity result in systemic oxidative stress and inflammation that deplete the vascular regenerative cell reservoir in the bone marrow that impairs blood vessel repair and exacerbates the penetrance of CVD co-morbidities. This novel translational paradigm, termed 'regenerative cell exhaustion' (RCE), can be detected as the depletion and dysfunction of hematopoietic and endothelial progenitor cell lineages in the peripheral blood of individuals with established T2D and/or obesity. The reversal of vascular RCE has been observed after administration of the sodium-glucose cotransporter-2 inhibitor (SGLT2i), empagliflozin, or after bariatric surgery for severe obesity. In this review, we explore emerging evidence that links improved dysglycemia to a reduction in systemic oxidative stress and recovery of circulating pro-vascular progenitor cell content required for blood vessel repair. Given that bariatric surgery consistently increases systemic glucagon-like-peptide 1 (GLP-1) release, we also focus on evidence that the use of GLP-1 receptor agonists (GLP-1RA) during obesity may act to inhibit the progression of systemic dysglycemia and adiposity, and indirectly reduce inflammation and oxidative stress, thereby limiting the impact of RCE. Therefore, therapeutic intervention with currently-available GLP-1RA may provide a less-invasive modality to reverse RCE, bolster vascular repair mechanisms, and improve cardiometabolic risk in individuals living with T2D and obesity.