Review

Authors: Kevin D Hall, Juen Guo

Weight changes are accompanied by imbalances between calorie intake and expenditure. This fact is often misinterpreted to suggest that obesity is caused by gluttony and sloth and can be treated by simply advising people to eat less and move more. Rather various components of energy balance are dynamically interrelated and weight loss is resisted by counterbalancing physiological processes. While low-carbohydrate diets have been suggested to partially subvert these processes by increasing energy expenditure and promoting fat loss, our meta-analysis of 32 controlled feeding studies with isocaloric substitution of carbohydrate for fat found that both energy expenditure (26 kcal/d; P <.0001) and fat loss (16 g/d; P <.0001) were greater with lower fat diets. We review the components of energy balance and the mechanisms acting to resist weight loss in the context of static, settling point, and set-point models of body weight regulation, with the set-point model being most commensurate with current data.

Topics: Body Weight Maintenance; Diet; Energy Intake; Energy Metabolism; Exercise; Feedback, Physiological; Humans; Models, Biological; Obesity; Rest; Thermogenesis; Weight Loss

PubMed: 28193517
DOI: 10.1053/j.gastro.2017.01.052

Meta-Analysis Review

Ketogenic Diet Benefits to Weight Loss, Glycemic Control, and Lipid Profiles in Overweight Patients with Type 2 Diabetes Mellitus: A Meta-Analysis of Randomized Controlled Trails.

Authors: Chong Zhou, Meng Wang, Jiling Liang...

A ketogenic diet, characterized by low calories with high levels of fat, adequate levels of protein, and low levels of carbohydrates, has beneficial effects on body weight control in overweight patients. In the present study, a meta-analysis was conducted to investigate the role of a ketogenic diet in body weight control and glycemic management in overweight patients with type 2 diabetes mellitus (T2DM). In summary, we systematically reviewed articles from the Embase, PubMed, Web of Science and Cochrane Library databases and obtained eight randomized controlled trials for meta-analysis. The results show that a ketogenic diet had significantly beneficial effects on the loss of body weight (SMD, -5.63, = 0.008), the reduction of waist circumference (SMD, -2.32, = 0.04), lowering glycated hemoglobin (SMD, -0.38, = 0.0008) and triglycerides (SMD, -0.36, = 0.0001), and increasing high-density lipoproteins (SMD, 0.28, = 0.003). Overall, these results suggest that a ketogenic diet may be an effective dietary intervention for body weight and glycemic control, as well as improved lipid profiles in overweight patients with T2DM. Hence, a ketogenic diet can be recommended for the therapeutic intervention of overweight patients with T2DM.

Topics: Blood Glucose; Body Weight; Diabetes Mellitus, Type 2; Diet, Ketogenic; Glycemic Control; Humans; Overweight; Triglycerides; Weight Loss

PubMed: 36012064
DOI: 10.3390/ijerph191610429

Review

Authors: Hyuna Sung, Rebecca L Siegel, Lindsey A Torre...

The prevalence of excess body weight and the associated cancer burden have been rising over the past several decades globally. Between 1975 and 2016, the prevalence of excess body weight in adults-defined as a body mass index (BMI) ≥ 25 kg/m -increased from nearly 21% in men and 24% in women to approximately 40% in both sexes. Notably, the prevalence of obesity (BMI ≥ 30 kg/m ) quadrupled in men, from 3% to 12%, and more than doubled in women, from 7% to 16%. This change, combined with population growth, resulted in a more than 6-fold increase in the number of obese adults, from 100 to 671 million. The largest absolute increase in obesity occurred among men and boys in high-income Western countries and among women and girls in Central Asia, the Middle East, and North Africa. The simultaneous rise in excess body weight in almost all countries is thought to be driven largely by changes in the global food system, which promotes energy-dense, nutrient-poor foods, alongside reduced opportunities for physical activity. In 2012, excess body weight accounted for approximately 3.9% of all cancers (544,300 cases) with proportion varying from less than 1% in low-income countries to 7% or 8% in some high-income Western countries and in Middle Eastern and Northern African countries. The attributable burden by sex was higher for women (368,500 cases) than for men (175,800 cases). Given the pandemic proportion of excess body weight in high-income countries and the increasing prevalence in low- and middle-income countries, the global cancer burden attributable to this condition is likely to increase in the future. There is emerging consensus on opportunities for obesity control through the multisectoral coordinated implementation of core policy actions to promote an environment conducive to a healthy diet and active living. The rapid increase in both the prevalence of excess body weight and the associated cancer burden highlights the need for a rejuvenated focus on identifying, implementing, and evaluating interventions to prevent and control excess body weight.

Topics: Body Mass Index; Cost of Illness; Female; Global Health; Humans; Male; Neoplasms; Obesity; Overweight; Prevalence; Risk Factors; Sex Factors

PubMed: 30548482
DOI: 10.3322/caac.21499

Review

Authors: Luca Busetto, Silvia Bettini, Janine Makaronidis...

Weight regain following weight loss is frequent problem that people with obesity face. This weight recidivism is often attributed to the lack of compliance with appropriate food habits and exercise. On the contrary, it is known that body weight and fat mass are regulated by numerous physiological mechanisms, far beyond voluntary food intake and physical exercise. Thus, the aim of this paper is to review the main peripheral and central mechanisms involved in weight regain. Gut hormone secretion profiles impact upon predisposition to weight regain according to an individual variability, although it is recognised a usual pattern of compensatory changes: a reduction in anorectic hormones secretion and an increase in orexigenic hormone. These changes lead to both increased appetite and reward value of food leading to increased energye intake. In addition, resting energy expenditure after weight loss is lower than expected according to body composition changes. This gap between observed and predicted energy expenditure following weight loss is named metabolic adaptation, which has been suggested to explain partly weight regain. This complicated scenario, beyond patient motivation, makes weight regain a challenge in long-term management interventions in patients with obesity.

Topics: Body Weight; Energy Intake; Energy Metabolism; Humans; Obesity; Weight Gain; Weight Loss

PubMed: 33461826
DOI: 10.1016/j.ejim.2021.01.002

Meta-Analysis

Authors: Qing Zhang, Caishun Zhang, Haidan Wang...

We conducted a systematic review and meta-analysis of randomized clinical trials and pilot trial studies to compare the effectiveness of intermittent fasting (IF) and continuous calorie restriction (CCR) in overweight and obese people. The parameters included body mass index (BMI), body weight, and other metabolism-related indicators. A systematic search in PubMed, Embase, Cochrane Library, and Web of Science was conducted up to January 2022. Standardized mean differences (SMDs) with 95% confidence intervals (CIs) were used to measure the effectiveness. Publication bias was assessed using Egger's test. The stability of the results was evaluated using sensitivity analyses. The significance of body weight change (SMD = -0.21, 95% CI (-0.40, -0.02) = 0.028) was more significant after IF than CCR. There was no significant difference in BMI (SMD = 0.02, 95% CI (-0.16, 0.20) = 0.848) between IF and CCR. These findings suggest that IF may be superior to CCR for weight loss in some respects.

Topics: Body Weight; Caloric Restriction; Fasting; Humans; Overweight; Weight Loss

PubMed: 35565749
DOI: 10.3390/nu14091781

Review

Authors: F L Greenway

Obesity is a major global health problem and predisposes individuals to several comorbidities that can affect life expectancy. Interventions based on lifestyle modification (for example, improved diet and exercise) are integral components in the management of obesity. However, although weight loss can be achieved through dietary restriction and/or increased physical activity, over the long term many individuals regain weight. The aim of this article is to review the research into the processes and mechanisms that underpin weight regain after weight loss and comment on future strategies to address them. Maintenance of body weight is regulated by the interaction of a number of processes, encompassing homoeostatic, environmental and behavioural factors. In homoeostatic regulation, the hypothalamus has a central role in integrating signals regarding food intake, energy balance and body weight, while an 'obesogenic' environment and behavioural patterns exert effects on the amount and type of food intake and physical activity. The roles of other environmental factors are also now being considered, including sleep debt and iatrogenic effects of medications, many of which warrant further investigation. Unfortunately, physiological adaptations to weight loss favour weight regain. These changes include perturbations in the levels of circulating appetite-related hormones and energy homoeostasis, in addition to alterations in nutrient metabolism and subjective appetite. To maintain weight loss, individuals must adhere to behaviours that counteract physiological adaptations and other factors favouring weight regain. It is difficult to overcome physiology with behaviour. Weight loss medications and surgery change the physiology of body weight regulation and are the best chance for long-term success. An increased understanding of the physiology of weight loss and regain will underpin the development of future strategies to support overweight and obese individuals in their efforts to achieve and maintain weight loss.

Topics: Adaptation, Physiological; Comorbidity; Diet, Reducing; Energy Intake; Energy Metabolism; Exercise; Homeostasis; Humans; Obesity; Social Environment; Weight Gain; Weight Loss

PubMed: 25896063
DOI: 10.1038/ijo.2015.59

Meta-Analysis

Authors: Giovanna Muscogiuri, Marwan El Ghoch, Annamaria Colao...

BACKGROUND

The very low-calorie ketogenic diet (VLCKD) has been recently proposed as an appealing nutritional strategy for obesity management. The VLCKD is characterized by a low carbohydrate content (<50 g/day), 1-1.5 g of protein/kg of ideal body weight, 15-30 g of fat/day, and a daily intake of about 500-800 calories.

OBJECTIVES

The aim of the current document is to suggest a common protocol for VLCKD and to summarize the existing literature on its efficacy in weight management and weight-related comorbidities, as well as the possible side effects.

METHODS

This document has been prepared in adherence with Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines. Literature searches, study selection, methodology development, and quality appraisal were performed independently by 2 authors and the data were collated by means of a meta-analysis and narrative synthesis.

RESULTS

Of the 645 articles retrieved, 15 studies met the inclusion criteria and were reviewed, revealing 4 main findings. First, the VLCKD was shown to result in a significant weight loss in the short, intermediate, and long terms and improvement in body composition parameters as well as glycemic and lipid profiles. Second, when compared with other weight loss interventions of the same duration, the VLCKD showed a major effect on reduction of body weight, fat mass, waist circumference, total cholesterol and triglyceridemia as well as improved insulin resistance. Third, although the VLCKD also resulted in a significant reduction of glycemia, HbA1c, and LDL cholesterol, these changes were similar to those obtained with other weight loss interventions. Finally, the VLCKD can be considered a safe nutritional approach under a health professional's supervision since the most common side effects are usually clinically mild and easily to manage and recovery is often spontaneous.

CONCLUSIONS

The VLCKD can be recommended as an effective dietary treatment for individuals with obesity after considering potential contra-indications and keeping in mind that any dietary treatment has to be personalized. Prospero Registry: The assessment of the efficacy of VLCKD on body weight, body composition, glycemic and lipid parameters in overweight and obese subjects: a meta-analysis (CRD42020205189).

Topics: Adult; Diet, Ketogenic; Humans; Obesity; Obesity Management; Overweight; Weight Loss

PubMed: 33882506
DOI: 10.1159/000515381

Authors: Kevin D Hall, Steven B Heymsfield, Joseph W Kemnitz...

Topics: Body Weight; Diet, Reducing; Energy Intake; Energy Metabolism; Exercise; Health Behavior; Humans; Models, Biological; Motor Activity; Obesity; Overweight

PubMed: 22434603
DOI: 10.3945/ajcn.112.036350

Meta-Analysis

Are Dietary Proteins the Key to Successful Body Weight Management? A Systematic Review and Meta-Analysis of Studies Assessing Body Weight Outcomes after Interventions with Increased Dietary Protein.

Authors: Thea Toft Hansen, Arne Astrup, Anders Sjödin...

The primary aim was to systematically review the current evidence investigating if dietary interventions rich in protein lead to improved body weight management in adults with excessive body weight. The secondary aim was to investigate potential modifying effects of phenotyping. A systematic literature search in PubMed, Web of Science, and Cochrane Library identified 375 randomized controlled trials with 43 unique trials meeting the inclusion criteria. The Cochrane collaboration tool was used for a thorough risk of bias assessment. Based on 37 studies evaluating effects of dietary protein on body weight, the participants with increased protein intake (ranging from 18-59 energy percentage [E%]) were found to reduce body weight by 1.6 (1.2; 2.0) kg (mean [95% confidence interval]) compared to controls (isocaloric interventions with energy reduction introduced in certain studies). Individuals with prediabetes were found to benefit more from a diet high in protein compared to individuals with normoglycemia, as did individuals without the obesity risk allele (AA genotype) compared to individuals with the obesity risk alleles (AG and GG genotypes). Thus, diets rich in protein would seem to have a moderate beneficial effect on body weight management.

Topics: Adult; Body Mass Index; Body Weight; Diet, High-Protein; Dietary Proteins; Exercise; Female; Humans; Male; Middle Aged; Obesity; Overweight; Randomized Controlled Trials as Topic; Weight Gain; Weight Loss; Young Adult

PubMed: 34579069
DOI: 10.3390/nu13093193

Meta-Analysis Review

Comparative effects of nutraceuticals on body weight in adults with overweight or obesity: A systematic review and network meta-analysis of 111 randomized clinical trials.

Authors: Hossein Shahinfar, Ahmad Jayedi, Kimia Torabynasab...

There is no research on the comparative effects of nutraceuticals on weight loss in adults with overweight or obesity. This study aimed at quantifying and ranking the effects of different nutraceuticals on weight loss. We searched PubMed, Scopus, and Web of Science to November 2022. We included randomized trials evaluating the comparative effects of two or more nutraceuticals, or compared a nutraceutical against a placebo for weight loss in adults with overweight or obesity. We conducted random-effects network meta-analysis with a Frequentist framework to estimate mean difference [MD] and 95% confidence interval [CI] of the effect of nutraceuticals on weight loss. One hundred and eleven RCTs with 6171 participants that investigated the effects of 18 nutraceuticals on body weight were eligible. In the main analysis incorporating all trials, there was high certainty of evidence for supplementation of spirulina (MD: -1.77 kg, 95% CI: -2.77, -0.78) and moderate certainty of evidence that supplementation of curcumin (MD: -0.82 kg, 95% CI: -1.33, -0.30), psyllium (MD: -3.70 kg, 95% CI: -5.18, -2.22), chitosan (MD: -1.70 kg, 95% CI: -2.62, -0.78), and Nigella sativa (MD: -2.09 kg, 95%CI: -2.92, -1.26) could result in a small improvement in body weight. Supplementations with green tea (MD: -1.25 kg, 95%CI: -1.68, -0.82) and glucomannan (MD: -1.36 kg, 95%CI: -2.17, -0.54) demonstrated small weight loss, also the certainty of evidence was rated low. Based on our findings, supplementations with nutraceuticals can result in a small weight loss in adults with overweight or obesity.

Topics: Adult; Humans; Overweight; Network Meta-Analysis; Randomized Controlled Trials as Topic; Body Weight; Obesity; Weight Loss; Dietary Supplements

PubMed: 37778464
DOI: 10.1016/j.phrs.2023.106944