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Physiological and Lifestyle Traits of Metabolic Dysfunction in the Absence of Obesity.
Klitgaard, HB, Kilbak, JH, Nozawa, EA, Seidel, AV, Magkos, F
Current diabetes reports. 2020;(6):17
Abstract
PURPOSE OF REVIEW Individuals with metabolically unhealthy normal weight (MUNW) have an adverse cardiometabolic risk factor profile in the absence of excess body weight, and increased risk for diabetes and heart disease. We critically review some physiological traits and lifestyle characteristics of the MUNW phenotype. RECENT FINDINGS The prevalence of MUNW varies considerably around the world and among ethnicities, partly because of different definitions; on average, this phenotype affects about ~ 30% of normal weight persons globally. Most studies have recruited MUNW subjects who, although within the normal weight range, are significantly "more obese" than their metabolically healthy lean peers (greater body mass index or total body fat); hence one cannot ascertain whether observed differences are true traits of the MUNW phenotype of simply secondary to greater relative adiposity within the normal range. Carefully matched studies have indicated that MUNW can exist in the absence of excess total body fat. These subjects have a preferential accumulation of fat in the upper body (abdominal subcutaneous and visceral adipose tissues) and the liver, but not skeletal muscle; perhaps surprisingly, this predominantly "android" fat distribution does not translate into increased waist circumference. The MUNW phenotype is associated with lower aerobic fitness and muscle mass and strength, but whether this is simply due to inadequate regular physical activity is not entirely clear. Likewise, no consistent associations have been found between any dietary factors and the development of MUNW phenotype, but diet-induced modest weight loss facilitates its resolution. Delineating the mechanisms leading to metabolic dysfunction in the absence of increased body weight and body fat will likely reveal important targets for improving metabolic health and eventually for reducing the burden of cardiometabolic disease, not only in individuals with normal body weight but also in people with obesity.
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The role of intermittent fasting and meal timing in weight management and metabolic health.
Templeman, I, Gonzalez, JT, Thompson, D, Betts, JA
The Proceedings of the Nutrition Society. 2020;(1):76-87
Abstract
Obesity remains a major public health concern and intermittent fasting is a popular strategy for weight loss, which may present independent health benefits. However, the number of diet books advising how fasting can be incorporated into our daily lives is several orders of magnitude greater than the number of trials examining whether fasting should be encouraged at all. This review will consider the state of current understanding regarding various forms of intermittent fasting (e.g. 5:2, time-restricted feeding and alternate-day fasting). The efficacy of these temporally defined approaches appears broadly equivalent to that of standard daily energy restriction, although many of these models of intermittent fasting do not involve fed-fasted cycles every other 24 h sleep-wake cycle and/or permit some limited energy intake outside of prescribed feeding times. Accordingly, the intervention period therefore may not regularly alternate, may not span all or even most of any given day, and may not even involve absolute fasting. This is important because potentially advantageous physiological mechanisms may only be initiated if a post-absorptive state is sustained by uninterrupted fasting for a more prolonged duration than applied in many trials. Indeed, promising effects on fat mass and insulin sensitivity have been reported when fasting duration is routinely extended beyond sixteen consecutive hours. Further progress will require such models to be tested with appropriate controls to isolate whether any possible health effects of intermittent fasting are primarily attributable to regularly protracted post-absorptive periods, or simply to the net negative energy balance indirectly elicited by any form of dietary restriction.
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Physiological mechanisms underlying children's circannual growth patterns and their contributions to the obesity epidemic in elementary school age children.
Moreno, JP, Crowley, SJ, Alfano, CA, Thompson, D
Obesity reviews : an official journal of the International Association for the Study of Obesity. 2020;(3):e12973
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Several studies since the 1990s have demonstrated that children increase their body mass index at a faster rate during summer months compared with the school year, leading some to conclude that the out-of-school summer environment is responsible. Other studies, however, have suggested that seasonality may play a role in children's height and weight changes across the year. This article reviews evidence for seasonal differences in the rate of children's height and weight gain and proposes potential physiological mechanisms that may explain these seasonal variations.
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Curbing Obesity from One Generation to Another: the Effects of Bariatric Surgery on the In Utero Environment and Beyond.
Spann, RA, Grayson, BE
Reproductive sciences (Thousand Oaks, Calif.). 2020;(10):1821-1833
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Approximately 250,000 individuals seek bariatric surgery each year in the USA for the long-term resolution of obesity-related comorbidities. Greater than 80% of these individuals are women and approximately half are of child-bearing age. Although there are many positive metabolic benefits that are realized through surgical weight loss for both men and women, the various long-term hormonal, molecular, nutrient, and epigenetic changes following bariatric surgery have not been evaluated for the surgical recipient or in the context of pregnancy and the offspring. Pregnancy may be a vulnerable period of time for the bariatric surgery recipient, and thoughtful consideration of pregnancy management should be taken by health care providers and recipients alike. The purpose of this review is to explore potential etiologies of some of the gestation-specific outcomes for the mother and offspring.
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The Implication of Gut Hormones in the Regulation of Energy Homeostasis and Their Role in the Pathophysiology of Obesity.
Koliaki, C, Liatis, S, Dalamaga, M, Kokkinos, A
Current obesity reports. 2020;(3):255-271
Abstract
PURPOSE OF REVIEW This review provides an update on the role of gut hormones and their interactions in the regulation of energy homeostasis, describes gut hormone adaptations in obesity and in response to weight loss, and summarizes the current evidence on the role of gut hormone-based therapies for obesity treatment. RECENT FINDINGS Gut hormones play a key role in regulating eating behaviour, energy and glucose homeostasis. Dysregulated gut hormone responses have been proposed to be pathogenetically involved in the development and perpetuation of obesity. Summarizing the major gut hormone changes in obesity, obese individuals are characterized by blunted postprandial ghrelin suppression, loss of premeal ghrelin peaks, impaired diurnal ghrelin variability and reduced fasting and postprandial levels of anorexigenic peptides. Adaptive alterations of gut hormone levels are implicated in weight regain, thus complicating hypocaloric dietary interventions, and can further explain the profound weight loss and metabolic improvement following bariatric surgery. A plethora of compounds mimicking gut hormone changes after bariatric surgery are currently under investigation, introducing a new era in the pharmacotherapy of obesity. The current trend is to combine different gut hormone receptor agonists and target multiple systems simultaneously, in order to replicate as closely as possible the gut hormone milieu after bariatric surgery and circumvent the counter-regulatory adaptive changes associated with dietary energy restriction. An increasing number of preclinical and early-phase clinical trials reveal the additive benefits obtained with dual or triple gut peptide receptor agonists in reducing body weight and improving glycaemia. Gut hormones act as potent regulators of energy and glucose homeostasis. Therapeutic strategies targeting their levels or receptors emerge as a promising approach to treat patients with obesity and hyperglycaemia.
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Association of anthropometry and weight change with risk of dementia and its major subtypes: A meta-analysis consisting 2.8 million adults with 57 294 cases of dementia.
Lee, CM, Woodward, M, Batty, GD, Beiser, AS, Bell, S, Berr, C, Bjertness, E, Chalmers, J, Clarke, R, Dartigues, JF, et al
Obesity reviews : an official journal of the International Association for the Study of Obesity. 2020;(4):e12989
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Uncertainty exists regarding the relation of body size and weight change with dementia risk. As populations continue to age and the global obesity epidemic shows no sign of waning, reliable quantification of such associations is important. We examined the relationship of body mass index, waist circumference, and annual percent weight change with risk of dementia and its subtypes by pooling data from 19 prospective cohort studies and four clinical trials using meta-analysis. Compared with body mass index-defined lower-normal weight (18.5-22.4 kg/m2 ), the risk of all-cause dementia was higher among underweight individuals but lower among those with upper-normal (22.5-24.9 kg/m2 ) levels. Obesity was associated with higher risk in vascular dementia. Similarly, relative to the lowest fifth of waist circumference, those in the highest fifth had nonsignificant higher vascular dementia risk. Weight loss was associated with higher all-cause dementia risk relative to weight maintenance. Weight gain was weakly associated with higher vascular dementia risk. The relationship between body size, weight change, and dementia is complex and exhibits non-linear associations depending on dementia subtype under scrutiny. Weight loss was associated with an elevated risk most likely due to reverse causality and/or pathophysiological changes in the brain, although the latter remains speculative.
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Nutrition and frailty: Current knowledge.
Feart, C
Progress in neuro-psychopharmacology & biological psychiatry. 2019;:109703
Abstract
PURPOSE OF THE REVIEW Nutrition, as part of lifestyle and modifiable environmental factors, constitutes an interesting approach for the prevention of geriatric syndromes. The objective of this review was to examine the most recent evidence on the association between nutrition, from dietary patterns to specific nutrients, and frailty, before the onset of disability, among elderly individuals. RECENT FINDINGS Based on available epidemiological studies, three meta-analyses published in 2018 have outlined a protective effect of greater adherence to a Mediterranean-type diet (MeDi) on the risk for frailty, with up to a 60% reduction in risk. Several studies focusing on particular food groups, macronutrients and micronutrients have also been published and have highlighted that a protein intake of 1 g/kg in body weight per day should be fulfilled (except for patients suffering from kidney or hepatic dysfunction) and that vitamin deficiencies should be avoided. Available interventional studies of nutritional supplements and/or physical activity programs have mainly been limited to disabled participants to date. SUMMARY Research efforts should target both developing a better understanding of the mechanisms underlying frailty and improving detection tools and the effectiveness of intervention studies, alongside efforts to address the specific needs of older people. For instance, ensuring an adequate nutritional status, by fighting the age-related increased prevalence of undernutrition or sarcopenic obesity, should be privileged.
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Non-caloric sweeteners and body weight.
Cavagnari, BM
Medicina. 2019;(2):115-122
Abstract
Both total caloric intake and consumption of free sugars is higher than recommended. This situation contributes, among many other factors, to the increase of overweight and obesity in the population. To maintain the sweet taste of foods and beverages while reducing the caloric content and the amount of free sugars in said products, many people choose to replace sugary products in their diet for options containing noncaloric sweeteners. This change in their dietary choice is accompanied by an increasing number of consultations with health professionals about the effects that non-caloric sweeteners could have on their body weight. Results reported in different scientific publications seem contradictory in relation to this topic: some of them, showing a positive association between the consumption of non-caloric sweeteners and energy intake and body weight, while others reporting that the consumption of these additives -in replacement of sugar- may lead to a reduction in caloric intake and body weight. The main objective of this article is to review the available evidence on the consumption of non-caloric sweeteners in relation to body weight, thus providing another tool for health professionals to make nutritional recommendations based on the best available evidence.
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Potential Mechanisms of Sodium-Glucose Co-Transporter 2 Inhibitor-Related Cardiovascular Benefits.
Verma, S
The American journal of cardiology. 2019;:S36-S44
Abstract
The findings of recent clinical trials have shown that sodium-glucose co-transporter 2 (SGLT2) inhibitors produce effects beyond glucose lowering and have demonstrated beneficial cardiovascular effects that have been observed across a broad range of patients with type 2 diabetes mellitus. In particular, the cardiovascular benefit results largely from substantial and early effects of SGLT2 inhibition on cardiovascular death and hospitalization for heart failure. Recent cardiovascular outcomes trials (CVOTs) have also shown that relative risk reductions in cardiovascular outcomes were observed with SGLT2 inhibition both in patients with current and prior heart failure. Since the observed reductions of cardiovascular outcomes with SGLT2 inhibitor therapy were observed much earlier than would be expected by an anti-atherosclerotic effect, these results have led to speculation about the potential underlying pathways. Suggested mechanisms include natriuresis and osmotic diuresis; reductions in inflammation, oxidative stress, and arterial stiffness; reductions in blood pressure and body weight; and possible renoprotective effects. These effects could produce cardiovascular benefits through a range of cardiac effects, including reduction in left ventricular load, attenuation of cardiac fibrosis and inflammation, and improved myocardial energy production. Other possible mechanisms include inhibition of sodium-hydrogen exchange, increases in erythropoietin levels, and reduction in myocardial ischemia or reperfusion injury. It is likely that a range of mechanisms underlie the observed cardiovascular benefits of SGLT2 inhibitors; further elucidation of these mechanisms will be answered by ongoing research.
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Effect of physical exercise and training on gastrointestinal hormones in populations with different weight statuses.
Zouhal, H, Sellami, M, Saeidi, A, Slimani, M, Abbassi-Daloii, A, Khodamoradi, A, El Hage, R, Hackney, AC, Ben Abderrahman, A
Nutrition reviews. 2019;(7):455-477
Abstract
Several types of hormones exert control over appetite in humans. This narrative review explores the effects of exercise and training on the concentrations of gastrointestinal hormones in healthy and obese individuals. It focuses on the major hormones of appetite regulation: ghrelin, glucagon-like peptide 1, peptide YY, cholecystokinin, leptin, and oxyntomodulin. In normal-weight and overweight individuals, responses to most of these hormones depend on the intensity of exercise and training. However, findings in obese individuals are limited in number and, to some degree, contradictory. Although some gastrointestinal hormones have been studied extensively (eg, leptin), most have not been investigated systematically. Further research is required to confirm the effectiveness of exercise and training on gut hormones and to better understand the effect of gut hormones on appetite and hunger suppression in individuals with obesity. Investigations to elucidate the impact of various forms of exercise that have recently engaged the public interest, eg, high-intensity interval training or concurrent aerobic and resistance training, are warranted.