Energy balance, body composition, sedentariness and appetite regulation: pathways to obesity

Black pepper-based beverage induced appetite-suppressing effects without altering postprandial glycaemia, gut and thyroid hormones or gastrointestinal well-being: a randomized crossover study in healthy subjects

Pleiotropic effects of spices on health, particularly on glucose metabolism and energy regulation, deserve further clinical investigation into their efficacy.

Energy expenditure in the etiology of human obesity: spendthrift and thrifty metabolic phenotypes and energy-sensing mechanisms

The pathogenesis of human obesity is the result of dysregulation of the reciprocal relationship between food intake and energy expenditure (EE), which influences daily energy balance and ultimately leads to weight gain. According to principles of energy homeostasis, a relatively lower EE in a setting of energy balance may lead to weight gain; however, results from different study groups are contradictory and indicate a complex interaction between EE and food intake which may differentially influence weight change in humans. Recently, studies evaluating the adaptive response of one component to perturbations of the other component of energy balance have revealed both the existence of differing metabolic phenotypes ("spendthrift" and "thrifty") resulting from overeating or underfeeding, as well as energy-sensing mechanisms linking EE to food intake, which might explain the propensity of an individual to weight gain. The purpose of this review is to debate the role that human EE plays on body weight regulation and to discuss the physiologic mechanisms linking EE and food intake. An increased understanding of the complex interplay between human metabolism and food consumption may provide insight into pathophysiologic mechanisms underlying weight gain, which may eventually lead to prevention and better treatment of human obesity.

A population-based, cross-sectional study of the prevalence and correlates of sedentary behaviour of adults with intellectual disabilities

BACKGROUND

High levels of sedentary behaviour have a negative impact on health and well-being. There is limited evidence on the prevalence and correlates of sedentary behaviour of adults with intellectual disabilities (ID).

METHODS

A population-based sample of adults with ID were invited to take part in a comprehensive health check programme. Demographic and health data were collected during a structured interview and physical examination. Screen time was used as a proxy measure of sedentary behaviour. Bivariate and multivariate statistical modelling examined correlates of screen time.

RESULTS

Fifty per cent of the 725 participants reported four or more hours of screen time per day. Male gender, higher levels of intellectual ability, mobility problems, obesity, not having hearing impairment and not having epilepsy were all significantly associated with higher screen time in the final multivariate model (R²  = 0.16; Hosmer-Lemeshow goodness of fit statistic P = 0.36).

CONCLUSIONS

This is the first study to publish population-based data on the prevalence and correlates of sedentary behaviour in adults with ID. Compared with adults who do not have ID, adults with ID have higher levels, and different correlates, of sedentary behaviour. A better understanding of the social context of sedentary behaviour will inform the design of effective behaviour change programmes for adults with ID.

Impact of a non-restrictive satiating diet on anthropometrics, satiety responsiveness and eating behaviour traits in obese men displaying a high or a low satiety phenotype

The aim of this study was to evaluate the impact of a non-restrictive satiating diet in men displaying various degrees of satiety efficiency. In all, sixty-nine obese men aged 41·5 (sd5·7) years were randomly assigned to a control (10–15, 55–60 and 30 % energy as protein, carbohydrate and lipid, respectively;n34) or satiating (20–25, 45–50 and 30–35 % energy as protein, carbohydrate and lipid, respectively;n35) diet for 16 weeks, and were classified as having a low (LSP) or high (HSP) satiety phenotype. Both diets were consumedad libitum. Changes in body weight, BMI, percent fat mass, waist circumference, satiety responsiveness and eating behaviour traits were assessed following the intervention. Dropout rates were higher in the control diet (44·1 %) compared with the satiating diet (8·6 %). Decreases in body weight, BMI and waist circumference were significant in both groups, yet HSP individuals lost more body weight than LSP individuals (P=0·048). Decreases in % fat mass were greater in the satiating diet (LSP: −2·1 (sd2·1) %;P<0·01 and HSP: −3·0 (sd2·5) %;P<0·001) compared with the control diet (LSP: −1·1 (sd2·5) % and HSP: −1·3 (sd2·6) %) (P=0·034). Satiety responsiveness was markedly improved in the satiating diet, whereas no significant changes were observed in the control group. Changes in dietary restraint (+3·3 (sd2·9) to +7·2 (sd5·5)), flexible control (+0·9 (sd1·4) to +2·3 (sd2·7)), rigid control (+2·2 (sd1·5) to +2·5 (sd2·8)), disinhibition (−2·8 (sd3·7) to −3·2 (sd2·6)) and susceptibility to hunger (−2·7 (sd4·1) to −4·6 (sd3·9)) were similar between the diets. Compared with the control diet, the satiating diet favoured adherence, decreased % fat mass and improved satiety responsiveness in both HSP and LSP individuals.

Mechanisms responsible for homeostatic appetite control: theoretical advances and practical implications

Homeostatic appetite control is part of a psychobiological system that has evolved to maintain an adequate supply of nutrients for growth and maintenance. The system links the physiological needs for energy with the behaviour that satisfies these needs (feeding), and is shaped by excitatory and inhibitory signals. Owing to rapid shifts in the food environment, homeostatic appetite control is not well adapted for modern-day human functioning. Areas covered: Homeostatic appetite control has two divisions. Tonic processes exert stable and enduring influences, with signals arising from bodily tissues and metabolism. Episodic processes fluctuate rapidly and are related to nutrient ingestion and the composition of foods consumed. Research in these areas incorporates potent endocrine signals that can influence behaviour. Expert commentary: The regulation of adipose tissue, and its impact on appetite (energy) homeostasis, has been heavily researched. More recently however, it has been demonstrated that fat-free mass has the potential to act as a tonic driver of food intake. A challenging issue is to determine how the post-prandial action of episodic satiety hormones and gastrointestinal mechanisms can effectively brake the metabolic drive to eat, in order to keep food intake under control and prevent a positive energy balance and fat accumulation.

Metformin, the aspirin of the 21st century: its role in gestational diabetes mellitus, prevention of preeclampsia and cancer, and the promotion of longevity

Metformin is everywhere. Originally introduced in clinical practice as an antidiabetic agent, its role as a therapeutic agent is expanding to include treatment of prediabetes mellitus, gestational diabetes mellitus, and polycystic ovarian disease; more recently, experimental studies and observations in randomized clinical trials suggest that metformin could have a place in the treatment or prevention of preeclampsia. This article provides a brief overview of the history of metformin in the treatment of diabetes mellitus and reviews the results of metaanalyses of metformin in gestational diabetes mellitus as well as the treatment of obese, non-diabetic, pregnant women to prevent macrosomia. We highlight the results of a randomized clinical trial in which metformin administration in early pregnancy did not reduce the frequency of large-for-gestational-age infants (the primary endpoint) but did decrease the frequency of preeclampsia (a secondary endpoint). The mechanisms by which metformin may prevent preeclampsia include a reduction in the production of antiangiogenic factors (soluble vascular endothelial growth factor receptor-1 and soluble endoglin) and the improvement of endothelial dysfunction, probably through an effect on the mitochondria. Another potential mechanism whereby metformin may play a role in the prevention of preeclampsia is its ability to modify cellular homeostasis and energy disposition, mediated by rapamycin, a mechanistic target. Metformin has a molecular weight of 129 Daltons and therefore readily crosses the placenta. There is considerable evidence to suggest that this agent is safe during pregnancy. New literature on the role of metformin as a chemotherapeutic adjuvant in the prevention of cancer and in prolonging life and protecting against aging is reviewed briefly. Herein, we discuss the mechanisms of action and potential benefits of metformin.

Posture Allocation Revisited: Breaking the Sedentary Threshold of Energy Expenditure for Obesity Management

There is increasing recognition that low-intensity physical activities of daily life play an important role in achieving energy balance and that their societal erosion through substitution with sedentary (mostly sitting) behaviors, whether occupational or for leisure, impact importantly on the obesity epidemic. This has generated considerable interest for better monitoring, characterizing, and promoting countermeasures to sedentariness through a plethora of low-level physical activities (e.g., active workstations, standing desks, sitting breaks), amid the contention that altering posture allocation (lying, sitting, standing) can modify energy expenditure to impact upon body weight regulation and health. In addressing this contention, this paper first revisits the past and more recent literature on postural energetics, with particular emphasis on potential determinants of the large inter-individual variability in the energy cost of standing and the impact of posture on fat oxidation. It subsequently analyses the available data pertaining to various strategies by which posture allocations, coupled with light physical activity, may increase energy expenditure beyond the sedentary threshold, and their relevance as potential targets for obesity management.

Fasting leptin and glucose in normal weight, over weight and obese men and women diabetes patients with and without clinical depression

A large number of diabetes patients suffer from major depression and are at high risk of mortality. In view of a role of leptin in diabetes, depression and energy homeostasis, the present study concerns circulating levels of leptin in different BMI groups of un-depressed and depressed diabetes patients. Six hundred thirty male and female patients with a primary diagnosis of diabetes were grouped according to BMI and with or without clinical symptoms of depression. Age matched healthy, normal weight male and female volunteers without clinical symptoms of depression or diabetes were taken as controls. Blood samples were obtained after an overnight fast of 12 h. Serum was stored for the determination of leptin and glucose. We found that there were more female than male diabetes patients with comorbid depression. Fasting leptin was higher in normal weight non-diabetes women than men; but comparable in normal weight men and women diabetes patients. Fasting glucose levels were higher in diabetes than non diabetes groups; values were comparable in men and women. Depression was associated with a decrease and increase in leptin respectively in normal-overweight and obese men and women diabetes patients. Glucose levels were also higher in obese depressed than un-depressed diabetes patients. The results suggested that the female gender is at greater risk to comorbid diabetes with depression. Adipo-insular axis plays an important role in diabetes, associated depression and in the greater risk of the female gender to comorbid diabetes with depression.

Perspective: A Historical and Scientific Perspective of Sugar and Its Relation with Obesity and Diabetes

Fructose-containing added sugars, such as sucrose and high-fructose corn syrup, have been experimentally, epidemiologically, and clinically shown to be involved in the current epidemics of obesity and diabetes. Here we track this history of intake of sugar as it relates to these epidemics. Key experimental studies that have identified mechanisms by which fructose causes obesity and diabetes are reviewed, as well as the evidence that the uricase mutation that occurred in the mid-Miocene in ancestral humans acted as a "thrifty gene" that increases our susceptibility for fructose-associated obesity today. We briefly review recent evidence that obesity can also be induced by nondietary sources of fructose, such as from the metabolism of glucose (from high-glycemic carbohydrates) through the polyol pathway. These studies suggest that fructose-induced obesity is driven by engagement of a "fat switch" and provide novel insights into new approaches for the prevention and treatment of these important diseases.

Stress, cortisol, and other appetite-related hormones: Prospective prediction of 6-month changes in food cravings and weight

OBJECTIVE

To examine whether baseline chronic stress, morning cortisol, and other appetite-related hormones (leptin, ghrelin, and insulin) predict future weight gain and food cravings in a naturalistic, longitudinal, 6-month follow-up study.

METHODS

A prospective community cohort of 339 adults (age 29.1 ± 9.0 years; BMI = 26.7 ± 5.4 kg/m² ; 56.9% female; 70.2% white) completed assessments at baseline and 6-month follow-up. Fasting blood draws were used to assess cortisol and other appetite-related hormone levels at baseline. At baseline and follow-up, body weight was measured, and the Cumulative Adversity Interview and Food Craving Inventory were administered. Data were analyzed using linear mixed models adjusting for demographic and clinical covariates.

RESULTS

Over the 6-month period, 49.9% of the sample gained weight. Food cravings and chronic stress decreased over 6 months (Ps < 0.05). However, after adjusting for covariates, individuals with higher baseline total ghrelin had significantly higher food cravings at 6 months (P = 0.04). Furthermore, higher cortisol, insulin, and chronic stress were each predictive of greater future weight gain (Ps < 0.05).

CONCLUSIONS

These results suggest that ghrelin plays a role in increased food cravings and reward-driven eating behaviors. Studies are needed that examine the utility of stress reduction methods for normalizing disrupted cortisol responses and preventing future weight gain.

Clinical Science-linking basic science to disease mechanisms

For more than 50 years, Clinical Science has been at the interface linking basic science to disease mechanisms. Here, Rhian Touyz, the Editor-in-Chief, describes the journal, its aims and scope, and recent developments.

Parasites, nutrition, immune responses and biology of metabolic tissues

Nutritional immunology, immunometabolism and identification of novel immunotherapeutic targets are areas of active investigation in parasitology. There is a well-documented crosstalk among immune cells and cells in metabolically active tissues that is important for homeostasis. The numbers and function of these cells are altered by obesity leading to inflammation. A variety of helminths spend some part of their life cycle in the gastrointestinal tract and even entirely enteral nematode infections exert beneficial effects on glucose and lipid metabolism. The foundation of this review is the ability of enteric nematode infections to improve obesity-induced type 2 diabetes and the metabolic syndrome, which are significant health issues in developed areas. It considers the impact of nutrition and specific nutritional deficiencies, which are occur in both undeveloped and developed areas, on the host's ability mount a protective immune response against parasitic nematodes. There are a number of proposed mechanisms by which parasitic nematodes can impact metabolism including effects gastrointestinal hormones, altering epithelial function and changing the number and/or phenotype of immune cells in metabolic tissues. Nematodes can also exert their beneficial effects through Th2 cytokines that activate the transcription factor STAT6, which upregulates genes that regulate glucose and lipid metabolism.

Collateral fattening: When a deficit in lean body mass drives overeating

In his last review entitled "Some Adventures in Body Composition," Gilbert Forbes reminded us that "lean body mass and body fat are in a sense companions." To what extent the lean body mass (or fat-free mass) component in this companionship impacts on energy intake is rarely a topic for discussion, amid a dominant adipocentric view of appetite control. Yet an analysis of the few human studies that have investigated the relationships between objectively measured food intake and body composition reveals a potentially important role for both an increase and a decrease in fat-free mass in the drive to eat. These studies are highlighted here, together with the implications of their findings for research directed as much toward the elucidation of peripheral signals and energy-sensing mechanisms that drive hunger and appetite, as toward understanding the mechanisms by which dieting and sedentariness predispose to fatness.

Passive and active roles of fat-free mass in the control of energy intake and body composition regulation

While putative feedback signals arising from adipose tissue are commonly assumed to provide the molecular links between the body's long-term energy requirements and energy intake, the available evidence suggests that the lean body or fat-free mass (FFM) also plays a role in the drive to eat. A distinction must, however, be made between a 'passive' role of FFM in driving energy intake, which is likely to be mediated by 'energy-sensing' mechanisms that translate FFM-induced energy requirements to energy intake, and a more 'active' role of FFM in the drive to eat through feedback signaling between FFM deficit and energy intake. Consequently, a loss of FFM that results from dieting or sedentarity should be viewed as a risk factor for weight regain and increased fatness not only because of the impact of the FFM deficit in lowering the maintenance energy requirement but also because of the body's attempt to restore FFM by overeating-a phenomenon referred to as 'collateral fattening'. A better understanding of these passive and active roles of FFM in the control of energy intake will necessitate the elucidation of peripheral signals and energy-sensing mechanisms that drive hunger and appetite, with implications for both obesity prevention and its management.

Defining Conditions for Optimal Inhibition of Food Intake in Rats by a Grape-Seed Derived Proanthocyanidin Extract

Food intake depends on homeostatic and non-homeostatic factors. In order to use grape seed proanthocyanidins (GSPE) as food intake limiting agents, it is important to define the key characteristics of their bioactivity within this complex function. We treated rats with acute and chronic treatments of GSPE at different doses to identify the importance of eating patterns and GSPE dose and the mechanistic aspects of GSPE. GSPE-induced food intake inhibition must be reproduced under non-stressful conditions and with a stable and synchronized feeding pattern. A minimum dose of around 350 mg GSPE/kg body weight (BW) is needed. GSPE components act by activating the Glucagon-like peptide-1 (GLP-1) receptor because their effect is blocked by Exendin 9-39. GSPE in turn acts on the hypothalamic center of food intake control probably because of increased GLP-1 production in the intestine. To conclude, GSPE inhibits food intake through GLP-1 signaling, but it needs to be dosed under optimal conditions to exert this effect.