Tissue losses and metabolic adaptations both contribute to the reduction in resting metabolic rate following weight loss

Physical Activity before and After Bariatric Surgery

Lifestyle changes including reduced calorie intake and increased physical activity (PA) improve the prognosis associated with bariatric surgery (BS) and metabolic indices. Early implementation of exercise leads to improved physical performance, better glycemic control and lipid profile, reduces the risks associated with anesthesia, and accelerates recovery from surgery. Undertaking systematic exercise after BS is associated with a better quality of life, improves insulin sensitivity, results in additional weight loss, reduces adverse effects on bone mass, and results in better body composition. The aim of this review was to summarize recommendations for physical activity in patients undergoing BS and to highlight the key role of physical activity in this patient group.

Evaluation of Intermittent Restricted Eating Using the Interval Weight Loss Online Platform in an Everyday Setting

Background/Objectives: Obesity remains a global health challenge. Many commercial online weight loss programs are available, and they have advantages in terms of scalability and access. Few of these programs have been evaluated for effectiveness in a real-world context. This study reports on the weight loss achieved, platform engagement, and characteristics of successful weight loss predictions in subscribers to the Interval Weight Loss (IWL) program. The Interval Weight Loss program promotes intermittent restricted eating in addition to lifestyle changes in diet composition, exercise, and sleep. Methods: Data for 1705 adults subscribing to the program for >30 days between 2019 and 2024 were included in the analysis. A linear mixed model with polynomial terms was used to model weight loss over time with interaction terms for gender and age. Survival analysis was used to model the proportions and time frame of those meeting 2%, 5%, and 10% weight loss targets and the proportion meeting their goal weight. The focus of the analysis was on the effect at 365 days. Descriptive data from a subset of participants (n = 205) who completed a questionnaire about change in lifestyle habits and mood are also presented. Results: Of those who stayed in the program for at least 365 days, 25.4% achieved their goal weight, 17.6% achieved a 10% weight loss, and 62% achieved a 5% weight loss. By 49 days, 50% had lost 2% of their weight. Significant interactions indicated that males and females in their 60s and 70s were the most responsive to the program. Conclusions: The online commercial Interval Weight Loss platform based on intermittent restricted eating resulted in significant weight loss in a cohort of subscribers in a real-world setting.

Effects of intermittent dieting with break periods on body composition and metabolic adaptation: a systematic review and meta-analysis

CONTEXT

Intermittent dieting incorporated with break periods (INT-B) has recently been promoted as an alternative dietary approach for optimal weight management.

OBJECTIVE

This study assessed the effectiveness of INT-B compared with that of conventional continuous energy restriction (CER) for improving body composition and attenuating metabolic adaptation.

DATA SOURCES

A systematic search was conducted on 6 databases using all available records until July 2023.

DATA EXTRACTION

The extracted data included the lead author, year of publication, population characteristics, intervention protocols, duration, and adherence.

DATA ANALYSIS

Random-effects meta-analyses were conducted for within-group and between-group comparisons of anthropometric and metabolic outcomes. Subgroup moderator analysis was performed for the types of INT-B, intervention duration, and population characteristics.

RESULTS

Of the 1469 records, 12 randomized trials (with 881 participants) were included. Within-group analyses demonstrated significant improvements in body mass, fat mass, body mass index, body fat percentage, and waist circumference following both INT-B and CER, with no significant group differences. However, resting metabolic rate (RMR) was significantly reduced following CER only. The compensatory reduction in RMR was significantly smaller following INT-B compared with CER, suggesting a lesser degree of metabolic adaptation. INT-B had a more significant effect on RMR retention in individuals with overweight/obesity compared with resistance-trained individuals.

CONCLUSION

This review provides up-to-date evidence for INT-B as a viable dietary strategy to improve body composition and attenuate metabolic adaptation.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42023448959.

mTORC1 in energy expenditure: consequences for obesity

In eukaryotic cells, the mammalian target of rapamycin complex 1 (sometimes referred to as the mechanistic target of rapamycin complex 1; mTORC1) orchestrates cellular metabolism in response to environmental energy availability. As a result, at the organismal level, mTORC1 signalling regulates the intake, storage and use of energy by acting as a hub for the actions of nutrients and hormones, such as leptin and insulin, in different cell types. It is therefore unsurprising that deregulated mTORC1 signalling is associated with obesity. Strategies that increase energy expenditure offer therapeutic promise for the treatment of obesity. Here we review current evidence illustrating the critical role of mTORC1 signalling in the regulation of energy expenditure and adaptive thermogenesis through its various effects in neuronal circuits, adipose tissue and skeletal muscle. Understanding how mTORC1 signalling in one organ and cell type affects responses in other organs and cell types could be key to developing better, safer treatments targeting this pathway in obesity.

Physical activity in metabolic syndrome

Obesity has become one of the global epidemics, contributing to the burden of disease in society, increasing the risk of diabetes, cardiovascular and liver diseases. Inadequate energy balance resulting from excessive energy intake and insufficient physical activity (PA) is one of the main factors contributing to the incidence of obesity and the development of metabolic syndrome (MetS). Treatment options for obesity include lifestyle modifications, pharmacotherapy and bariatric surgery, with the latter being the most effective treatment. Lifestyle interventions involving increased PA and reduced caloric intake improve metabolic outcomes. Early implementation of exercise leads to improved physical fitness, better glycemic control and lipid profile. Undertaking systematic PA is associated with better quality of life, improves insulin sensitivity, causes additional weight loss, reduces its adverse effects on bone mass and results in better body composition. In this narrative review we summarized the current state of knowledge on the impact of PA on the components of MetS and the latest recommendations for PA in patients with MetS.

Loss of body weight and lean mass in long-stay, hospitalized canine patients

A high prevalence of malnutrition occurs in human hospitals and has been associated with detrimental consequences. By comparison, much less is known in hospitalized veterinary patients. The aims of this study were to evaluate the prevalence of malnutrition and body composition changes in long-stay hospitalised patients using an isotopic dilution technique. An additional objective was to compare the changes in composition with commonly used methods measuring body fat and lean mass. The dogs consumed on average 77.5% of their estimated resting energy requirements during their stay. The majority (78.3%) of dogs lost body weight, of which a greater proportion was lean mass (61.8%) than fat mass (FM) (38.2%). There was a moderate correlation between body condition score and percentage FM measured at admission (Kendall's τ = 0.51; p = 0.002), and at discharge (Kendall's τ = 0.55; p = 0.001). However, there was no correlation between muscle condition score and fat-free mass at either admission or discharge (p > 0.1). Duration of stay was positively associated with loss of body weight (p < 0.001), but was not associated with changes in either lean or FM expressed as a percentage of body weight or in absolute terms (p > 0.1), which was presumed to be explained by small sample size and variation. Food intake was not found to a significant factor for lean or FM loss (p > 0.1). These findings indicate that weight loss is common in hospitalized canine patients, which is not explained by simple under-eating. Other factors such as inflammation and inactivity should be evaluated in future studies to determine their role in influencing muscle and FM changes in hospitalized canine patients.

Does eating less or exercising more to reduce energy availability produce distinct metabolic responses?

When less energy is available to consume, people often lose weight, which reduces their overall metabolic rate. Their cellular metabolic rate may also decrease (metabolic adaptation), possibly reflected in physiological and/or endocrinological changes. Reduced energy availability can result from calorie restriction or increased activity energy expenditure, raising the following question that our review explores: do the body's metabolic and physiological responses to this reduction differ or not depending on whether they are induced by dietary restriction or increased activity? First, human studies offer indirect, contentious evidence that the body metabolically adapts to reduced energy availability, both in response to either a calorie intake deficit or increased activity (exercise; without a concomitant increase in food intake). Considering individual aspects of the body's physiology as constituents of whole-body metabolic rate, similar responses to reduced energy availability are observed in terms of reproductive capacity, somatic maintenance and hormone levels. By contrast, tissue phenotypic responses differ, most evidently for skeletal tissue, which is preserved in response to exercise but not calorie restriction. Thus, while in many ways 'a calorie deficit is a calorie deficit', certain tissues respond differently depending on the energy deficit intervention. This article is part of a discussion meeting issue 'Causes of obesity: theories, conjectures and evidence (Part I)'.

The Influence of Energy Balance and Availability on Resting Metabolic Rate: Implications for Assessment and Future Research Directions

Resting metabolic rate (RMR) is a significant contributor to an individual's total energy expenditure. As such, RMR plays an important role in body weight regulation across populations ranging from inactive individuals to athletes. In addition, RMR may also be used to screen for low energy availability and energy deficiency in athletes, and thus may be useful in identifying individuals at risk for the deleterious consequences of chronic energy deficiency. Given its importance in both clinical and research settings within the fields of exercise physiology, dietetics, and sports medicine, the valid assessment of RMR is critical. However, factors including varying states of energy balance (both short- and long-term energy deficit or surplus), energy availability, and prior food intake or exercise may influence resulting RMR measures, potentially introducing error into observed values. The purpose of this review is to summarize the relationships between short- and long-term changes in energetic status and resulting RMR measures, consider these findings in the context of relevant recommendations for RMR assessment, and provide suggestions for future research.

Eating contexts determine the efficacy of nutrient warning labels to promote healthy food choices

Introduction

Unhealthy food choices increase the risk of obesity and its co-morbidities. Nutrition labels are a public health policy that aims to drive individuals toward healthier food choices. Chile has been an example of this policy, where mandatory nutrient warning labels (NWL) identify processed foods high in calories and critical nutrients. Eating contexts influence individual food choices, but whether eating contexts also influence how NWL alter the decision process and selection during food choice is unknown.

Methods

In an online mouse-tracking study, participants prompted to health, typical, or unrestricted eating contexts were instructed to choose between pairs of foods in the presence or absence of NWL. Conflict during choices was analyzed using mouse paths and reaction times.

Results

NWL increased conflict during unhealthy food choices and reduced conflict during healthy choices in all contexts. However, the probability that NWL reversed an unhealthy choice was 80% in a healthy, 37% in a typical, and 19% in an unrestricted context. A drift-diffusion model analysis showed the effects of NWL on choice were associated with an increased bias toward healthier foods in the healthy and typical but not in the unrestricted context.

Discussion

These data suggest that the efficacy of NWL to drive healthy food choices increases in a healthy eating context, whereas NWL are less effective in typical or unrestricted eating contexts.

Effectiveness of Adherence to a Mediterranean Diet in the Management of Overweight Women: The Prospective Interventional Cohort Study

Evidence indicates that unhealthy eating habits constitute multilevel obstacles threatening health and well-being. Studies suggest that consumer choices have turned irremovably towards Western diets. The Mediterranean diet (MD) is considered one of the most effective in preventing and treating overweight and obesity, yet its results and associations are ambiguous. This explanatory research aims to examine the effect of the MD on anthropometric and biochemical variables in 181 females from an Eastern European country. The sample was divided into three distinct clusters based on age (tricenarian, quadragenarian, and quinquagenarian). Anthropometric and biochemical examinations in the three-month MD program plan failed to provide convincing evidence of the benefits of the MD on selected integrands. However, total body fat (FATP) values between groups showed a significant difference (p ≤ 0.032) between groups A and C (p ≤ 0.029), which can be attributed to the age of the cohort (30-39 vs. 50-60 years). Values in groups A and B (p ≤ 0.001) and C and A (p ≤ 0.001) were significant between the cohorts but did not indicate any changes in visceral fat (VFATL) in the individual groups. The presented findings can have implications for further investigation and the development of more comprehensive instruments, incorporating critical add-on constituents that will be appropriate to monitor, evaluate, and predict body weight management in experimentation.

Thirty Obesity Myths, Misunderstandings, and/or Oversimplifications: An Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) 2022

Background

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) is intended to provide clinicians an overview of 30 common obesity myths, misunderstandings, and/or oversimplifications.

Methods

The scientific support for this CPS is based upon published citations, clinical perspectives of OMA authors, and peer review by the Obesity Medicine Association leadership.

Results

This CPS discusses 30 common obesity myths, misunderstandings, and/or oversimplifications, utilizing referenced scientific publications such as the integrative use of other published OMA CPSs to help explain the applicable physiology/pathophysiology.

Conclusions

This Obesity Medicine Association (OMA) Clinical Practice Statement (CPS) on 30 common obesity myths, misunderstandings, and/or oversimplifications is one of a series of OMA CPSs designed to assist clinicians in the care of patients with the disease of obesity. Knowledge of the underlying science may assist the obesity medicine clinician improve the care of patients with obesity.