Metabolic Adaptations to Weight Loss

Body Size Measurements Grouped Independently of Common Clinical Measures of Metabolic Health: An Exploratory Factor Analysis

BACKGROUND

Obesity is commonly aggregated with indices of metabolic health. Proponents of body positivity approaches question whether body size is a determinant of health and well-being. Our objective was to conduct an exploratory factor analysis (EFA) to determine if body size measurements factor load with or independent of metabolic health measures.

METHODS

The EFA was conducted on n= 249 adults using baseline data from four weight loss trials (Sample 1: n = 40; Sample 2: n = 52; Sample 3: n = 53; Sample 4: n = 104). An EFA of nine items (systolic blood pressure [SBP], diastolic blood pressure [DBP], hemoglobin A1c [HbA1c], HDL-cholesterol [HDL], LDL-cholesterol [LDL], total cholesterol [TC], body mass index [BMI], body fat percent BF%], and waist circumference [WC]) was conducted with oblique rotation.

RESULTS

Three factors were retained, which produced a model explaining 87.5% of the variance. Six items loaded strongly (>0.8) under three components and were selected for retention (Factor 1: LDL and TC; Factor 2: BMI and WC; Factor 3: SBP and DBP).

CONCLUSION

Body size measures loaded separately from measures of metabolic health and metabolic health were further split into lipid- and blood pressure-focused factors. These results support weight-neutral interventions to improve overall health and well-being.

Obesity

Obesity is a common condition and a major cause of morbidity and mortality. Fortunately, weight loss treatment can reduce obesity-related complications. This review summarizes the evidence-based strategies physicians can employ to identify, prevent, and treat obesity, including best practices to diagnose and counsel patients, to assess and address the burden of weight-related disease including weight stigma, to address secondary causes of weight gain, and to help patients set individualized and realistic weight loss goals and an effective treatment plan. Effective treatments include lifestyle modification and adjunctive therapies such as antiobesity medications and metabolic and bariatric surgery.

Abdominal Obesity Genetic Variants Predict Waist Circumference Regain After Weight Loss

Although many individuals are able to achieve weight loss, maintaining this loss over time is challenging. We aimed to study whether genetic predisposition to general or abdominal obesity predicts weight regain after weight loss. We examined the associations between genetic risk scores for higher BMI and higher waist-to-hip ratio adjusted for BMI (WHRadjBMI) with changes in weight and waist circumference up to 3 years after a 1-year weight loss program in participants (n = 822 women, n = 593 men) from the Look AHEAD (Action for Health in Diabetes) study who had lost ≥3% of their initial weight. Genetic predisposition to higher BMI or WHRadjBMI was not associated with weight regain after weight loss. However, the WHRadjBMI genetic score did predict an increase in waist circumference independent of weight change. To conclude, a genetic predisposition to higher WHRadjBMI predicts an increase in abdominal obesity after weight loss, whereas genetic predisposition to higher BMI is not predictive of weight regain. These results suggest that genetic effects on abdominal obesity may be more pronounced than those on general obesity during weight regain.

ARTICLE HIGHLIGHTS

Nearly all individuals who intentionally lose weight experience weight regain. Individuals with a higher genetic risk for abdominal adiposity experience increased regain in waist circumference after weight loss. Genetic predisposition to higher BMI does not predict weight regain after weight loss.

Phenotype tailored lifestyle intervention on weight loss and cardiometabolic risk factors in adults with obesity: a single-centre, non-randomised, proof-of-concept study

Background

Lifestyle interventions for weight loss are currently not individualised to underlying pathophysiology and behavioral traits in obesity. We aim to compare the outcome of a standard lifestyle intervention (SLI) to phenotype-tailored lifestyle interventions (PLI) on weight loss, cardiometabolic risk factors and physiologic variables contributing to obesity.

Methods

This 12-week, single-centre non-randomised proof-of-concept clinical trial including men and women aged 18-65 years with a body mass index (BMI) greater than 30 without history of any bariatric procedure, and current use of any medication known to affect weight. Participants lived anywhere in the United States, and underwent in-person testing in Rochester, MN at a teaching hospital. All participants completed in-person phenotype testing at baseline and after 12 weeks. Participants were assigned to their intervention based on their period of enrollment. In the first phase, participants were assigned to SLI with a low-calorie diet (LCD), moderate physical activity, and weekly behavioral therapy sessions. In the second phase, other participants were assigned to PLI according to phenotype: abnormal satiation (time-restricted volumetric LCD); abnormal postprandial satiety (LCD with pre-meal protein supplementation); emotional eating (LCD with intensive behavioral therapy); and abnormal resting energy expenditure (LCD with post-workout protein supplementation and high-intensity interval training). The primary outcome was total body weight loss in kg at 12 weeks using multiple imputation for missing data. Linear models estimated the association of study group allocation and study endpoints adjusting for age, sex, and baseline weight. This study was registered with ClinicalTrials.gov, NCT04073394.

Findings

Between July 2020 and August 2021, 211 participants were screened, and 165 were assigned to one of the two treatments in the two phases: 81 SLI (mean [SD] age 42.9 [12] years; 79% women; BMI 38.0 [6.0]) and 84 PLI (age 44.8 [12.2] years; 83% women; BMI 38.7 [6.9]); 146 completed the 12-week programs. The weight loss was -7.4 kg (95%CI, -8.8, -6.0) with PLI vs. -4.3 kg (95%CI, -5.8, -2.7) with SLI (difference, -3.1 kg [95%CI, -5.1 to -1.1]; P = 0.004). No adverse events were reported in any group.

Interpretation

Phenotype-tailored lifestyle interventions may result in significant weight loss, but a randomised controlled trial is required to confirm causality.

Funding

Mayo Clinic; NIH (K23-DK114460).

When fat meets the gut-focus on intestinal lipid handling in metabolic health and disease

The regular overconsumption of energy‐dense foods (rich in lipids and sugars) results in elevated intestinal nutrient absorption and consequently excessive accumulation of lipids in the liver, adipose tissue, skeletal muscles, and other organs. This can eventually lead to obesity and obesity‐associated diseases such as type 2 diabetes (T2D), non‐alcoholic fatty liver disease (NAFLD), cardiovascular disease, and certain types of cancer, as well as aggravate inflammatory bowel disease (IBD). Therefore, targeting the pathways that regulate intestinal nutrient absorption holds significant therapeutic potential. In this review, we discuss the molecular and cellular mechanisms controlling intestinal lipid handling, their relevance to the development of metabolic diseases, and emerging therapeutic strategies.

Satiety Associated with Calorie Restriction and Time-Restricted Feeding: Peripheral Hormones

Calorie restriction (CR) is a common approach to inducing negative energy balance. Recently, time-restricted feeding (TRF), which involves consuming food within specific time windows during a 24-h day, has become popular owing to its relative ease of practice and potential to aid in achieving and maintaining a negative energy balance. TRF can be implemented intentionally with CR, or TRF might induce CR simply because of the time restriction. This review focuses on summarizing our current knowledge on how TRF and continuous CR affect gut peptides that influence satiety. Based on peer-reviewed studies, in response to CR there is an increase in the orexigenic hormone ghrelin and a reduction in fasting leptin and insulin. There is likely a reduction in glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and cholecystokinin (CCK), albeit the evidence for this is weak. After TRF, unlike CR, fasting ghrelin decreased in some TRF studies, whereas it showed no change in several others. Further, a reduction in fasting leptin, insulin, and GLP-1 has been observed. In conclusion, when other determinants of food intake are held equal, the peripheral satiety systems appear to be somewhat similarly affected by CR and TRF with regard to leptin, insulin, and GLP-1. But unlike CR, TRF did not appear to robustly increase ghrelin, suggesting different influences on appetite with a potential decrease of hunger after TRF when compared with CR. However, there are several established and novel gut peptides that have not been measured within the context of CR and TRF, and studies that have evaluated effects of TRF are often short-term, with nonuniform study designs and highly varying temporal eating patterns. More evidence and studies addressing these aspects are needed to draw definitive conclusions.

Redox Homeostasis in Cardiovascular Disease: The Role of Mitochondrial Sirtuins

Cardiovascular disease (CVD) is still the leading cause of death worldwide. Despite successful advances in both pharmacological and lifestyle strategies to fight well-established risk factors, the burden of CVD is still increasing. Therefore, it is necessary to further deepen our knowledge of the pathogenesis of the disease for developing novel therapies to limit even more its related morbidity and mortality. Oxidative stress has been identified as a common trait of several manifestations of CVD and could be a promising target for innovative treatments. Mitochondria are a major source of oxidative stress and sirtuins are a family of enzymes that generate different post-translational protein modifications, thus regulating important cellular processes, including cell cycle, autophagy, gene expression, and others. In particular, three sirtuins, SIRT3, SIRT4, and SIRT5 are located within the mitochondrial matrix where they regulate energy production and antioxidant pathways. Therefore, these sirtuins are strongly involved in the balance between oxidant and antioxidant mechanisms. In this review, we summarize the activities of these sirtuins with a special focus on their role in the control of oxidative stress, in relation to energy metabolism, atherosclerosis, and CVD.

Pathophysiology of Obesity

As obesity continues a relentless march across the globe, researchers are beginning to unlock the complicated interplay among obesity, its ensuing inflammation, and downstream complications. It is becoming clear that obesity is a chronic, multifactorial, inflammatory disease of maladaptive adipose tissue mass involving complex links among genetics, hormonal-signaling, and the environment. Understanding the intricate pathogenesis of obesity and its sequela will go a long way to discovering better treatment options and lessen anti-obesity bias.

Management of Obesity and Nonalcoholic Fatty Liver Disease: A Literature Review

With the recent urbanization and globalization, the adult obesity rate has been increasing, which was paralleled with a dramatic surge in the incidence and prevalence of nonalcoholic fatty liver disease (NAFLD). NAFLD poses a growing threat to human health as it represents the most common cause of chronic liver disease in developed countries. It encompasses a wide spectrum of conditions starting from a build-up of fat in hepatocytes (steatosis), to developing inflammation (steatohepatitis), and reaching up to cirrhosis. It is also associated with higher rates of cardiovascular mortalities. Therefore, proper timely treatment is essential and weight loss remains the cornerstone in the treatment of obesity-related liver diseases. When diet, exercise, and lifestyle changes are not successful, the current recommendation for weight loss includes antiobesity medications and bariatric endoscopic and surgical interventions. These interventions have shown to result in significant weight loss and improve liver steatosis and fibrosis. In the current literature review, we highlight the expected outcomes and side effects of the currently existing options to have a weight-centric NAFLD approach.

History of Weight Cycling Is Prospectively Associated With Shorter and Poorer-Quality Sleep and Higher Sleep Apnea Risk in Diverse US Women

BACKGROUND

Poor sleep and history of weight cycling (HWC) are associated with worse cardiovascular health, yet limited research has evaluated the association between HWC and poor sleep patterns.

METHODS

The American Heart Association Go Red for Women Strategically Focused Research Network cohort at Columbia University (n = 506; mean age, 37 ± 15.7 years; 61% racial/ethnic minority) was used to evaluate the cross-sectional associations of HWC and sleep at baseline and the prospective associations of HWC from baseline with sleep at the 1-year visit. History of weight cycling, defined as losing and gaining 10 lb or more at least once (excluding pregnancy), was self-reported. Sleep duration, sleep quality, insomnia severity, and obstructive sleep apnea risk were assessed using the validated Pittsburgh Sleep Quality Index, Insomnia Severity Index, and Berlin questionnaires. Linear and logistic regression models, adjusted for age, race/ethnicity, education, health insurance status, pregnancy history, and menopausal status, were used to evaluate the relation of HWC with sleep.

RESULTS

Most women reported 1 or more episodes of weight cycling (72%). In linear models of cross-sectional and prospective data, each additional weight cycling episode was related to shorter sleep duration, poorer sleep quality, longer sleep onset latency, greater insomnia severity, more sleep disturbances, lower sleep efficiency, and higher sleep medication use frequency. In the logistic models, HWC (≥1 vs 0 episodes) was associated with greater odds for short sleep, poor sleep quality, long sleep onset latency (≥26 minutes), high obstructive sleep apnea risk, and sleep efficiency lower than 85%.

CONCLUSION

History of weight cycling predicted poor sleep among women, suggesting that weight maintenance may represent an important strategy to promote sleep health. The potential bidirectional relationship between HWC and sleep requires further investigation.

Projecting the Influence of Sugar-Sweetened Beverage Warning Labels and Restaurant Menu Labeling Regulations on Energy Intake, Weight Status, and Health Care Expenditures in US Adults: A Microsimulation

BACKGROUND

Accurate, readily accessible, and easy-to-understand nutrition labeling is a promising policy strategy to address poor diet quality and prevent obesity.

OBJECTIVE

This study projected the influence of nationwide implementation of sugar-sweetened beverage (SSB) warning labels and restaurant menu labeling regulations.

DESIGN

A stochastic microsimulation model was built to estimate the influences of SSB warning labels and menu labeling regulations on daily energy intake, body weight, body mass index, and health care expenditures among US adults.

PARTICIPANTS/SETTING

The model used individual-level data from the National Health and Nutrition Examination Survey, Medical Expenditure Panel Survey, and other validated sources.

STATISTICAL ANALYSES PERFORMED

The model was simulated using the bootstrapped samples, and the means and associated 95% CIs of the policy effects were estimated.

RESULTS

SSB warning labels and restaurant menu labeling regulations were estimated to reduce daily energy intake by 19.13 kcal (95% CI 18.83 to 19.43 kcal) and 33.09 kcal (95% CI 32.39 to 33.80 kcal), body weight by 0.92 kg (95% CI 0.90 to 0.93 kg) and 1.57 kg (95% CI 1.54 to 1.60 kg), body mass index by 0.32 (95% CI 0.31 to 0.33) and 0.55 (95% CI =0.54 to 0.56), and per-capita health care expenditures by $26.97 (95% CI $26.56 to $27.38) and $45.47 (95% CI $44.54 to $46.40) over 10 years, respectively. The reduced per-capita health care expenditures translated into an annual total medical cost saving of $0.69 billion for SSB warning labels and $1.16 billion for menu labeling regulations. No discernable policy effect on all-cause mortality was identified. The policy effects could be heterogeneous across population subgroups, with larger effects in men, non-Hispanic Black adults, and younger adults.

CONCLUSIONS

SSB warning labels and menu labeling regulations could be effective policy leverage to prevent weight gains and reduce medical expenses attributable to adiposity.

Physiology of weight regain: Lessons from the classic Minnesota Starvation Experiment on human body composition regulation

Since its publication in 1950, the Biology of Human Starvation, which describes the classic longitudinal Minnesota Experiment of semistarvation and refeeding in healthy young men, has been the undisputed source of scientific reference about the impact of long-term food deprivation on human physiology and behavior. It has been a guide in developing famine and refugee relief programs for international agencies, in exploring the effects of food deprivation on the cognitive and social functioning of those with anorexia nervosa and bulimia nervosa, and in gaining insights into metabolic adaptations that undermine obesity therapy and cachexia rehabilitation. In more recent decades, the application of a systems approach to the analysis of its data on longitudinal changes in body composition, basal metabolic rate, and food intake during the 24 weeks of semistarvation and 20 weeks of refeeding has provided rare insights into the multitude of control systems that govern the regulation of body composition during weight regain. These have underscored an internal (autoregulatory) control of lean-fat partitioning (highly sensitive to initial adiposity), which operates during weight loss and weight regain and revealed the existence of feedback loops between changes in body composition and the control of food intake and adaptive thermogenesis for the purpose of accelerating the recovery of fat mass and fat-free mass. This paper highlights the general features and design of this grueling experiment of simulated famine that has allowed the unmasking of fundamental control systems in human body composition autoregulation. The integration of its outcomes constitutes the "famine reactions" that drive the normal physiology of weight regain and obesity relapse and provides a mechanistic "autoregulation-based" explanation of how dieting and weight cycling, transition to sedentarity, or developmental programming may predispose to obesity. It also provides a system physiology framework for research toward elucidating proteinstatic and adipostatic mechanisms that control hunger-appetite and adaptive thermogenesis, with major implications for a better understanding (and management) of cachexia, obesity, and cardiometabolic diseases.