Blood glucose and meal patterns in time-blinded males, after aspartame, carbohydrate, and fat consumption, in relation to sweetness perception

The impact of non-nutritive sweeteners on fertility, maternal and child health outcomes: a review of human and animal studies

There is significant evidence that an unhealthy diet greatly increases the risk of complications during pregnancy and predisposes offspring to metabolic dysfunction and obesity. While fat intake is typically associated with the onset of obesity and its comorbidities, there is increasing evidence linking sugar, particularly high fructose corn syrup, to the global rise in obesity rates. Furthermore, the detrimental effects of added sugar intake during pregnancy on mother and child have been clearly outlined. Guidelines advising pregnant women to avoid food and beverages with high fat and sugar have led to an increase in consumption of 'diet' or 'light' options. Examination of some human birth cohort studies shows that heavy consumption (at least one beverage a day) of non-nutritive sweetener (NNS) containing beverages has been associated with increased risk of preterm birth and increased weight/BMI in male offspring independent of maternal weight, which appears to be offset by breastfeeding for 6 months. Rodent models have shown that NNS exposure during pregnancy can impact maternal metabolic health, adipose tissue function, gut microbiome profiles and taste preference. However, the mechanisms underlying these effects are multifaceted and further research, particularly in a translational setting is required to fully understand the effects of NNS on maternal and infant health during pregnancy. Therefore, this review examines maternal sweetener intakes and their influence on fertility, maternal health outcomes and offspring outcomes in human cohort studies and rodent models.

Effect of Non- and Low-Caloric Sweeteners on Substrate Oxidation, Energy Expenditure, and Catecholamines in Humans-A Systematic Review

The use of non- and low-caloric sweetener(s) (NCS and LCS) as a means to prevent overweight and obesity is highly debated, as both NCS and LCS have been proposed to have a negative impact on energy homeostasis. This systematic review aimed to assess the impact of NCS and LCS on fasting and postprandial substrate oxidation, energy expenditure, and catecholamines, compared to caloric sweeteners or water, across different doses and types of NCS and LCS, acutely and in the longer-term. A total of 20 studies were eligible: 16 studies for substrate oxidation and energy expenditure and four studies for catecholamines. Most studies compared the acute effects of NCS or LCS with caloric sweeteners under non-isoenergetic conditions. These studies generally found higher fat oxidation and lower carbohydrate oxidation with NCS or LCS than with caloric sweeteners. Findings for energy expenditure were inconsistent. With the limited number of studies, no convincing pattern for the remaining outcomes and comparisons could be seen. In conclusion, drinks or meals with NCS or LCS resulted in higher fat and lower carbohydrate oxidation compared to caloric sweeteners. No other conclusions could be drawn due to insufficient or inconsistent results. Further studies in this research field are warranted.

The physiological control of eating: signals, neurons, and networks

During the past 30 yr, investigating the physiology of eating behaviors has generated a truly vast literature. This is fueled in part by a dramatic increase in obesity and its comorbidities that has coincided with an ever increasing sophistication of genetically based manipulations. These techniques have produced results with a remarkable degree of cell specificity, particularly at the cell signaling level, and have played a lead role in advancing the field. However, putting these findings into a brain-wide context that connects physiological signals and neurons to behavior and somatic physiology requires a thorough consideration of neuronal connections: a field that has also seen an extraordinary technological revolution. Our goal is to present a comprehensive and balanced assessment of how physiological signals associated with energy homeostasis interact at many brain levels to control eating behaviors. A major theme is that these signals engage sets of interacting neural networks throughout the brain that are defined by specific neural connections. We begin by discussing some fundamental concepts, including ones that still engender vigorous debate, that provide the necessary frameworks for understanding how the brain controls meal initiation and termination. These include key word definitions, ATP availability as the pivotal regulated variable in energy homeostasis, neuropeptide signaling, homeostatic and hedonic eating, and meal structure. Within this context, we discuss network models of how key regions in the endbrain (or telencephalon), hypothalamus, hindbrain, medulla, vagus nerve, and spinal cord work together with the gastrointestinal tract to enable the complex motor events that permit animals to eat in diverse situations.

Exiguous premeal saccharide intake reduces subsequent food intake in men

Purpose

Satiety is a crucial factor in the attempt to reduce food intake for long-term body weight loss. Since there is evidence for a negative correlation between cerebral energy levels and food intake, the provision of the primary energy substrate glucose to the brain through oral ingestion of carbohydrates could trigger feelings of satiety. Therefore, we hypothesized that a low-calorie saccharide preload would increase satiety, reduce subsequent food intake, and thereby decrease overall calorie consumption.

Methods

In a randomized single-blind crossover study, 17 healthy young normal-weight men received saccharide (26 kcal in total) or placebo capsules 30 min before a standardized breakfast buffet. We analysed food intake from the test buffet as well as plasma glucose and serum insulin levels.

Results

The saccharide preload reduced food intake from the buffet by 168 (± 34) kcal (p < 0.001) compared to control. This corresponds to a net reduction in total calorie consumption by 142 (± 34) kcal (p < 0.001) or 9.3% due to saccharide capsules.

Conclusion

A very low-calorie saccharide preload considerably reduces subsequent food intake leading to decreased overall calorie consumption. A saccharide preload before meals could, therefore, be a promising support for reducing caloric intake.

German Clinical Trials Register

DRKS00010281 (date of registration: 11.04.2016)

Effect of sucralose and aspartame on glucose metabolism and gut hormones

Non-nutritive sweeteners are thought to be useful replacements for caloric sweeteners in sweet food and beverages, since the reduction in energy and carbohydrate intake may lead to health benefits stemming from weight management and glycemic control. However, the potential effects of non-nutritive sweeteners on glucose metabolism and gut hormones have not been determined definitively. Here, the available evidence of the effects of aspartame and sucralose consumption on glucose metabolism and gut hormones is reviewed. A majority of studies have found that consumption of aspartame or sucralose has no effect on concentrations of blood glucose, insulin, or gut hormones; however, 2 trials have shown that aspartame consumption affects glucose, insulin, and glucagon-like peptide 1 concentrations, while only a few trials have shown that sucralose consumption affects glucose, insulin, and glucagon-like peptide 1 concentrations. One study found higher glucose concentrations after sucralose consumption, while 3 studies found lower concentrations and 33 studies found no change in glucose concentrations. Moreover, only 4 studies reported increased concentrations of glucagon-like peptide 1. Three studies reported decreased insulin sensitivity following sucralose consumption, while 1 trial reported an increase in insulin sensitivity. In summary, the evidence from the clinical trials conducted to date is contradictory because of the different protocols used.

Insulin signaling in AgRP neurons regulates meal size to limit glucose excursions and insulin resistance

The importance of hypothalamic insulin signaling on feeding and glucose metabolism remains unclear. We report that insulin acts on AgRP neurons to acutely decrease meal size and thereby limit postprandial glucose and insulin excursions. The promotion of insulin signaling in AgRP neurons decreased meal size without altering total caloric intake, whereas the genetic ablation of the insulin receptor had the opposite effect. The promotion of insulin signaling also decreased the intake of sucrose-sweetened water or high-fat food over standard chow, without influencing food-seeking and hedonic behaviors. The ability of heightened insulin signaling to override the hedonistic consumption of highly palatable high-fat food attenuated the development of systemic insulin resistance, without affecting body weight. Our findings define an unprecedented mechanism by which insulin acutely influences glucose metabolism. Approaches that enhance insulin signaling in AgRP neurons may provide a means for altering feeding behavior in a nutrient-dense environment to combat the metabolic syndrome.

Contribution of macronutrients to obesity: implications for precision nutrition

The specific metabolic contribution of consuming different energy-yielding macronutrients (namely, carbohydrates, protein and lipids) to obesity is a matter of active debate. In this Review, we summarize the current research concerning associations between the intake of different macronutrients and weight gain and adiposity. We discuss insights into possible differential mechanistic pathways where macronutrients might act on either appetite or adipogenesis to cause weight gain. We also explore the role of dietary macronutrient distribution on thermogenesis or energy expenditure for weight loss and maintenance. On the basis of the data discussed, we describe a novel way to manage excessive body weight; namely, prescribing personalized diets with different macronutrient compositions according to the individual's genotype and/or enterotype. In this context, the interplay of macronutrient consumption with obesity incidence involves mechanisms that affect appetite, thermogenesis and metabolism, and the outcomes of these mechanisms are altered by an individual's genotype and microbiota. Indeed, the interactions of the genetic make-up and/or microbiota features of a person with specific macronutrient intakes or dietary pattern consumption help to explain individualized responses to macronutrients and food patterns, which might represent key factors for comprehensive precision nutrition recommendations and personalized obesity management.

Effect of Plain Versus Sugar-Sweetened Breakfast on Energy Balance and Metabolic Health: A Randomized Crossover Trial

OBJECTIVE

This study investigated the effect of 3 weeks of high-sugar ("Sweet") versus low-sugar ("Plain") breakfast on energy balance, metabolic health, and appetite.

METHODS

A total of 29 healthy adults (22 women) completed this randomized crossover study. Participants had pre- and postintervention appetite, health, and body mass outcomes measured, and they recorded diet, appetite (visual analogue scales), and physical activity for 8 days during each intervention. Interventions were 3 weeks of isoenergetic Sweet (30% by weight added sugar; average 32 g of sugar) versus Plain (no added sugar; average 8 g of sugar) porridge-based breakfasts.

RESULTS

Pre- to postintervention changes in body mass were similar between Plain (Δ 0.1 kg; 95% CI: -0.3 to 0.5 kg) and Sweet (Δ 0.2 kg; 95% CI: -0.2 to 0.5 kg), as were pre- to postintervention changes for biomarkers of health (all P ≥ 0.101) and psychological appetite (all P ≥ 0.152). Energy, fat, and protein intake was not statistically different between conditions. Total carbohydrate intake was higher during Sweet (287 ± 82 g/d vs. 256 ± 73 g/d; P = 0.009), driven more by higher sugar intake at breakfast (116 ± 46 g/d vs. 88 ± 38 g/d; P < 0.001) than post-breakfast sugar intake (Sweet 84 ± 42 g/d vs. Plain 80 ± 37 g/d; P = 0.552). Participants reported reduced sweet desire immediately after Sweet but not Plain breakfasts (trial × time P < 0.001).

CONCLUSIONS

Energy balance, health markers, and appetite did not respond differently to 3 weeks of high- or low-sugar breakfasts.

A narrative review of the effects of sugar-sweetened beverages on human health: A key global health issue

The provision of healthy and safe food is vital for human health, and the addition of unnecessary sugars in foodstuffs is an important global issue, leading to multiple long- and short-term health issues and spiraling costs for individuals and governments alike. The negative effect of excess sugar consumption contributes to adverse health conditions, including obesity, type 2 diabetes, and poor oral health in both high and low resource settings. A key plank of governmental and health promotion bodies' nutritional guidance is to raise public awareness of "hidden" sugars, salt, and fats, such as found in processed foods and sugar-sweetened beverages (SSBs), and guide individuals to reduce their consumption. This rapid narrative review brings together some of the key issues identified in the literature around the consumption of SSBs, including patterns of consumption, the general impact on human health and nutrition, specific effects on oral health and the oral microbiome, and strategies to address over-consumption. The range of long-term adverse effects on health is often misunderstood or unknown by the public. However, some strategies have succeeded in reducing the consumption of SSBs, including public health strategies and interventions and the imposition of taxes or levies, and this article makes recommendations for action.

Non-nutritive Sweeteners and Glycaemic Control

PURPOSE OF REVIEW

The consumption of foods and beverages containing non-nutritive sweeteners (NNS) has increased worldwide over the last three decades. Consumers' choice of NNS rather than sugar or other nutritive sweeteners may be attributable to their potential to reduce weight gain.

RECENT FINDINGS

It is not clear what the effects of NNS consumption are on glycaemic control and the incidence of type 2 diabetes. This review aims to examine this question in epidemiological, human intervention and animal studies. It is not clear that NNS consumption has an effect on the incidence of type 2 diabetes or on glycaemic control even though there is some evidence for the modification of the microbiome and for interaction with sweet taste receptors in the oral cavity and the intestines' modification of secretion of glucagon-like peptide-1 (GLP-1), peptide YY (PYY), ghrelin and glucose-dependent insulinotropic polypeptide (GIP), which may affect glycaemia following consumption of NNS. In conclusion, long-term studies of NNS consumption are required to draw a firm conclusion about the role of NNS consumption on glycaemic control.

The effect of the artificial sweeteners on glucose metabolism in healthy adults: a randomized, double-blinded, crossover clinical trial

This study aimed to determine the effect of pure forms of sucralose and aspartame, in doses reflective of common consumption, on glucose metabolism. Healthy participants consumed pure forms of a non-nutritive sweetener (NNS) that were mixed with water and standardized to doses of 14% (0.425 g) of the acceptable daily intake (ADI) for aspartame and 20% (0.136 g) of the ADI for sucralose every day for 2 weeks. Blood samples were collected and analyzed for glucose, insulin, active glucagon-like peptide-1 (GLP-1), and leptin. Seventeen participants (10 females and 7 males; age, 24 ± 6.8 years; body mass index, 22.9 ± 2.5 kg/m²) participated in the study. The total area under the curve values of glucose, insulin, active GLP-1 and leptin were similar for the aspartame and sucralose treatment groups compared with the baseline values in healthy participants. There was no change in insulin sensitivity after NNS treatment compared with the baseline values. These findings suggest that daily repeated consumption of pure sucralose or aspartame for 2 weeks had no effect on glucose metabolism among normoglycaemic adults. However, these results need to be tested in studies with longer durations. Novelty Daily consumption of pure aspartame or sucralose for 2 weeks had no effect on glucose metabolism. Daily consumption of pure aspartame or sucralose for 2 weeks had no effect on insulin sensitivity among healthy adults.

Sweet Nothings

Abstract. Prior research has suggested that circulating levels of glucose in the bloodstream help to determine success at self-control. However, this idea has been challenged on multiple grounds. The current research added new evidence to the debate by testing (1) the extent to which exercising self-control reduces blood glucose levels, (2) whether consuming glucose, rinsing the mouth with glucose, or consuming aspartame (a sugar substitute) increases blood glucose levels, and (3) the extent to which measured blood glucose levels relate to emotional responding, delay discounting, and cognitive control, respectively. We found no evidence that blood glucose levels influence or are influenced by self-control.

Energy Expenditure, Carbohydrate Oxidation and Appetitive Responses to Sucrose or Sucralose in Humans: A Pilot Study

Background: In light of obesity, replacing sugar with non-nutritive sweeteners is commonly used to reduce sugar content of food products. This study aimed to compare human energy expenditure (EE), carbohydrate oxidation and food intake after the ingestion of test foods sweetened with sucrose or a non-nutritive sweetener. Methods: This was an acute crossover feeding study that entailed consumption of three test foods: jelly sweetened with 50 g sucrose (SUCROSE), with 120 mg of sucralose only (NNS), or 120 mg sucralose but matched in carbohydrate with 50 g maltodextrin (MALT). On test days, participants arrived at the research facility after an overnight fast. Resting energy expenditure (indirect calorimeter) was measured for 30 min followed by jelly consumption. Participants’ EE and substrate oxidation were measured for 90 min subsequently. After EE assessment, participants completed a meal challenge before leaving the research facility, and recorded food intake for the remaining day. Subjective appetite ratings were assessed before and after test foods and meal challenge. Results: Eleven participants completed the study. EE was higher in SUCROSE and MALT than NNS, but not statistically significant. Carbohydrate oxidation was SUCROSE > MALT > NNS (p < 0.001). Earlier and bigger rise in carbohydrate oxidation was observed in SUCROSE than MALT, although both were carbohydrate-matched. NNS did not promote energy expenditure, carbohydrate oxidation or stimulate appetite. Conclusions: Foods sweetened with sucrose or non-nutritive sweeteners but matched in carbohydrate content have different effects on human EE and carbohydrate oxidation. Sucralose alone did not affect EE, but lower energy in the test food from sugar replacement was eventually fully compensated. Findings from this pilot study should be verified with bigger clinical studies in the future to establish clinical relevance.

Positive and negative incentive contrasts lead to relative value perception in ants

Humans usually assess things not according to their absolute value, but relative to reference points - a main tenant of Prospect Theory. For example, people rate a new salary relative to previous salaries and salaries of their peers, rather than absolute income. We demonstrate a similar effect in an insect: ants expecting to find low-quality food showed higher acceptance of medium-quality food than ants expecting medium quality, and vice versa for high expectations. Further experiments demonstrate that these contrast effects arise from cognitive rather than mere sensory or pre-cognitive perceptual causes. Social information gained inside the nest can also serve as a reference point: the quality of food received from other ants affected the perceived value of food found later. Value judgement is a key element in decision making, and thus relative value perception strongly influences which option is chosen and ultimately how all animals make decisions.

Do non-nutritive sweeteners influence acute glucose homeostasis in humans? A systematic review

The human body associates sensory cues with metabolic consequences. Exposure to sweet-tasting sugars - even in the absence of ingestion - triggers physiological responses that are associated with carbohydrate digestion, absorption and metabolism. These responses include the release of insulin and incretin hormones, which work to reduce blood glucose. For this reason, non-nutritive sweeteners (NNS) have been posited to trigger similar physiological responses and reduce postprandial blood glucose concentrations. The first part of this review presents a brief overview of sweet taste receptor activation in the oral cavity and gastrointestinal tract and the ensuing physiological responses related to glucose homeostasis. The second part of this review contains a systematic literature review that tested the hypothesis that NNS use improves glucose regulation postprandially. Studies were grouped based on sweet taste receptor stimulation paradigms, including pre-ingestive stimulation, ingestion of NNS alone, co-ingestion of NNS with foods, and using NNS as preloads to influence subsequent blood glucose excursions. In summary, the review found that NNS triggered physiological responses, albeit inconsistently, yet failed to significantly lower blood glucose levels in almost all studies.

Health outcomes of non-nutritive sweeteners: analysis of the research landscape

BACKGROUND

Food products containing non-nutritive sweeteners (NNSs) instead of sugar have become increasingly popular in the last decades. Their appeal is obviously related to their calorie-free sweet taste. However, with the dramatic increase in their consumption, it is reasonable and timely to evaluate their potential health benefits and, more importantly, potential adverse effects. The main aim of this scoping review was to map the evidence about health outcomes possibly associated with regular NNS consumption by examining the extent, range, and nature of research activity in this area.

METHODS

We systematically searched Ovid MEDLINE, EMBASE and the Cochrane CENTRAL databases for studies on NNSs (artificial sweeteners or natural, non-caloric sweeteners, either used individually or in combination) using text terms with appropriate truncation and relevant indexing terms. All human studies investigating any health outcomes of a NNS intervention or exposure were eligible for inclusion. No studies were excluded based on language, study design or methodological quality. Data for each health outcome were summarized in tabular form and were discussed narratively.

RESULTS

Finally, we included 372 studies in our scoping review, comprising 15 systematic reviews, 155 randomized controlled trials (RCTs), 23 non-randomized controlled trials, 57 cohort studies, 52 case-control studies, 28 cross sectional studies and 42 case series/case reports. In healthy subjects, appetite and short term food intake, risk of cancer, risk of diabetes, risk of dental caries, weight gain and risk of obesity are the most investigated health outcomes. Overall there is no conclusive evidence for beneficial and harmful effects on those outcomes. Numerous health outcomes including headaches, depression, behavioral and cognitive effects, neurological effects, risk of preterm delivery, cardiovascular effects or risk of chronic kidney disease were investigated in fewer studies and further research is needed. In subjects with diabetes and hypertension, the evidence regarding health outcomes of NNS use is also inconsistent.

CONCLUSIONS

This scoping review identifies the needs for future research to address the numerous evidence gaps related to health effects of NNSs use.It also specifies the research questions and areas where a systematic review with meta-analyses is required for the proper evaluation of health outcomes associated to regular NNSs consumption.

Metabolic effects of aspartame in adulthood: A systematic review and meta-analysis of randomized clinical trials

Data about harms or benefits associated with the consumption of aspartame, a nonnutritive sweetener worldwide consumed, are still controversial. This systematic review and meta-analysis of randomized controlled clinical trials aimed to assess the effect of aspartame consumption on metabolic parameters related to diabetes and obesity. The search was performed on Cochrane, LILACS, PubMed, SCOPUS, Web of Science databases, and on a gray literature using Open Grey, Google Scholar, and ProQuest Dissertations & Theses Global. Searches across all databases were conducted from the earliest available date up to April 13, 2016, without date and language restrictions. Pooled mean differences were calculated using a random or fixed-effects model for heterogeneous and homogenous studies, respectively. Twenty-nine articles were included in qualitative synthesis and twelve, presenting numeric results, were used in meta-analysis. Fasting blood glucose (mmol/L), insulin levels (μU/mL), total cholesterol (mmol/L), triglycerides concentrations (mmol/L), high-density lipoprotein cholesterol (mmol/L), body weight (kg), and energy intake (MJ) were considered as the main outcomes in subjects that consumed aspartame, and results were presented as mean difference; % confidence interval, range. Aspartame consumption was not associated with alterations on blood glucose levels compared to control (-0.03 mmol/L; 95% CI, -0.21 to 0.14) or to sucrose (0.31 mmol/L; 95% CI, -0.05 to 0.67) and on insulin levels compared to control (0.13 μU/mL; 95% CI, -0.69 to 0.95) or to sucrose (2.54 μU/mL; 95% CI, -6.29 to 11.37). Total cholesterol was not affected by aspartame consumption compared to control (-0.02 mmol/L; 95% CI, -0.31 to 0.27) or to sucrose (-0.24 mmol/L; 95% CI, -0.89 to 0.42). Triglycerides concentrations were not affected by aspartame consumption compared to control (0.00 mmol/L; 95% CI, -0.04 to 0.05) or to sucrose (0.00 mmol/L; 95% CI, -0.09 to 0.09). High-density lipoprotein cholesterol serum levels were higher on aspartame compared to control (-0.03 mmol/L; 95% CI, -0.06 to -0.01) and lower on aspartame compared to sucrose (0.05 mmol/L; 95% CI, 0.02 to 0.09). Body weight did not change after aspartame consumption compared to control (5.00 kg; 95% CI, -1.56 to 11.56) or to sucrose (3.78 kg; 95% CI, -2.18 to 9.74). Energy intake was not altered by aspartame consumption compared to control (-0.49 MJ; 95% CI, -1.21 to 0.22) or to sucrose (-0.17 MJ; 95% CI, -2.03 to 1.69). Data concerning effects of aspartame on main metabolic variables associated to diabetes and obesity do not support a beneficial related to its consumption.

Effects of the Non-Nutritive Sweeteners on Glucose Metabolism and Appetite Regulating Hormones: Systematic Review of Observational Prospective Studies and Clinical Trials

Background

The effects of non-nutritive sweeteners (NNS) on glucose metabolism and appetite regulating hormones are not clear. There is an ongoing debate concerning NNS use and deleterious changes in metabolism.

Objectives

The aim of this review is to analyze the scientific available evidence regarding the effects of NNS on glucose metabolism and appetite regulating hormones.

Data Sources and Study Eligibility Criteria

We identified human observational studies evaluating the relation between NNS consumption and obesity, diabetes, and metabolic syndrome, in addition to clinical trials evaluating the effects of NNS in glucose metabolism and appetite regulating hormones.

Results

Fourteen observational studies evaluating the association between NNS consumption and the development of metabolic diseases and twenty-eight clinical trials studying the effects of NNS on metabolism were included. Finally, two meta-analyses evaluating the association between the consumption of NNS-containing beverages and the development of type 2 diabetes were identified.

Conclusions

Some observational studies suggest an association between NNS consumption and development of metabolic diseases; however, adiposity is a confounder frequently found in observational studies. The effects of the NNS on glucose metabolism are not clear. The results of the identified clinical trials are contradictory and are not comparable because of the major existing differences between them. Studies evaluating specific NNS, with an adequate sample size, including a homogeneous study group, identifying significant comorbidities, with an appropriate control group, with an appropriate exposure time, and considering adjustment for confounder variables such as adiposity are needed.

Fatty acid-induced astrocyte ketone production and the control of food intake

Obesity and Type 2 diabetes are major worldwide public health issues today. A relationship between total fat intake and obesity has been found. In addition, the mechanisms of long-term and excessive high-fat diet (HFD) intake in the development of obesity still need to be elucidated. The ventromedial hypothalamus (VMH) is a major site involved in the regulation of glucose and energy homeostasis where "metabolic sensing neurons" integrate metabolic signals from the periphery. Among these signals, fatty acids (FA) modulate the activity of VMH neurons using the FA translocator/CD36, which plays a critical role in the regulation of energy and glucose homeostasis. During low-fat diet (LFD) intake, FA are oxidized by VMH astrocytes to fuel their ongoing metabolic needs. However, HFD intake causes VMH astrocytes to use FA to generate ketone bodies. We postulate that these astrocyte-derived ketone bodies are exported to neurons where they produce excess ATP and reactive oxygen species, which override CD36-mediated FA sensing and act as a signal to decrease short-term food intake. On a HFD, VMH astrocyte-produced ketones reduce elevated caloric intake to LFD levels after 3 days in rats genetically predisposed to resist (DR) diet-induced obesity (DIO), but not leptin-resistant DIO rats. This suggests that, while VMH ketone production on a HFD can contribute to protection from obesity, the inherent leptin resistance overrides this inhibitory action of ketone bodies on food intake. Thus, astrocytes and neurons form a tight metabolic unit that is able to monitor circulating nutrients to alter food intake and energy homeostasis.

Sleep, circadian rhythm and body weight: parallel developments

Circadian alignment is crucial for body-weight management, and for metabolic health. In this context, circadian alignment consists of alignment of sleep, meal patterns and physical activity. During puberty a significant reduction in sleep duration occurs, and pubertal status is inversely associated with sleep duration. A consistent inverse association between habitual sleep duration and body-weight development occurs, independent of possible confounders. Research on misalignment reveals that circadian misalignment affects sleep-architecture and subsequently disturbs glucose–insulin metabolism, substrate oxidation, leptin- and ghrelin concentrations, appetite, food reward, hypothalamic–pituitary–adrenal-axis activity and gut-peptide concentrations enhancing positive energy balance and metabolic disturbance. Not only aligning meals and sleep in a circadian way is crucial, also regular physical activity during the day strongly promotes the stability and amplitude of circadian rhythm, and thus may serve as an instrument to restore poor circadian rhythms. Endogenicity may play a role in interaction of these environmental variables with a genetic predisposition. In conclusion, notwithstanding the separate favourable effects of sufficient daily physical activity, regular meal patterns, sufficient sleep duration and quality sleep on energy balance, the overall effect of the amplitude and stability of the circadian rhythm, perhaps including genetic predisposition, may integrate the separate effects in an additive way.

The role of alginates in regulation of food intake and glycemia: a gastroenterological perspective

Regulation of food intake through modulation of gastrointestinal responses to ingested foods is an ever-growing component of the therapeutic approaches targeting the obesity epidemic. Alginates, viscous and gel-forming soluble fibers isolated from the cell wall of brown seaweeds and some bacteria, are recently receiving considerable attention because of their potential role in satiation, satiety, and food intake regulation in the short term. Enhancement of gastric distension, delay of gastric emptying, and attenuation of postprandial glucose responses may constitute the basis of their physiological benefits. Offering physical, chemical, sensorial, and physiological advantages over other viscous and gel-forming fibers, alginates constitute promising functional food ingredients for the food industry. Therefore, the current review explores the role of alginates in food intake and glycemic regulation, their underlying modes of action and their potential in food applications.

Does low-energy sweetener consumption affect energy intake and body weight? A systematic review, including meta-analyses, of the evidence from human and animal studies

By reducing energy density, low-energy sweeteners (LES) might be expected to reduce energy intake (EI) and body weight (BW). To assess the totality of the evidence testing the null hypothesis that LES exposure (versus sugars or unsweetened alternatives) has no effect on EI or BW, we conducted a systematic review of relevant studies in animals and humans consuming LES with ad libitum access to food energy. In 62 of 90 animal studies exposure to LES did not affect or decreased BW. Of 28 reporting increased BW, 19 compared LES with glucose exposure using a specific ‘learning' paradigm. Twelve prospective cohort studies in humans reported inconsistent associations between LES use and body mass index (−0.002 kg m⁻² per year, 95% confidence interval (CI) −0.009 to 0.005). Meta-analysis of short-term randomized controlled trials (129 comparisons) showed reduced total EI for LES versus sugar-sweetened food or beverage consumption before an ad libitum meal (−94 kcal, 95% CI −122 to −66), with no difference versus water (−2 kcal, 95% CI −30 to 26). This was consistent with EI results from sustained intervention randomized controlled trials (10 comparisons). Meta-analysis of sustained intervention randomized controlled trials (4 weeks to 40 months) showed that consumption of LES versus sugar led to relatively reduced BW (nine comparisons; −1.35 kg, 95% CI –2.28 to −0.42), and a similar relative reduction in BW versus water (three comparisons; −1.24 kg, 95% CI –2.22 to −0.26). Most animal studies did not mimic LES consumption by humans, and reverse causation may influence the results of prospective cohort studies. The preponderance of evidence from all human randomized controlled trials indicates that LES do not increase EI or BW, whether compared with caloric or non-caloric (for example, water) control conditions. Overall, the balance of evidence indicates that use of LES in place of sugar, in children and adults, leads to reduced EI and BW, and possibly also when compared with water.

Sugar-sweetened beverages and cardio-metabolic disease risks

PURPOSE OF REVIEW

Sucrose-sweetened beverages (SSB) have for decades been implicated in cardiometabolic diseases. The purpose of this review is to summarize recent epidemiological but particularly recent human intervention studies on the metabolic effects associated/induced by SSB.

RECENT FINDINGS

Recent epidemiological studies support the positive association between SSB intake and enhanced risk for metabolic syndrome, type 2 diabetes, coronary heart diseases, and stroke. From the human intervention studies rather similar results are obtained with enhanced accumulation of fat in the liver, muscle, and in the visceral fat depot induced by SSB. Moreover, SSB induces enhanced levels of circulating triglycerides and enhanced de-novo lipogenesis in the liver. The specific effect of SSB on body weigh/obesity is still not completely elucidated but SSB enhances body weight/fat mass even though not to a significant degree in all studies. Concerning the mechanisms for SSB to induce these metabolic aberrations most of the studies are in agreement with the fact that it is mainly fructose (free or as part of the sucrose molecule) that is the main driver of these metabolic aberrations presumably primarily by inducing lipid synthesis in and release from the liver.

SUMMARY

There are now convincing evidences for enhanced cardiometabolic risk after higher intake of SSB where both epidemiological studies and human intervention studies are pointing in the same direction. A so-called 'well tolerated' intake of SSB is not determined. Accordingly, intake of SSB should generally be reduced as much as possible to improve the health of the population.

Chronobiology, endocrinology, and energy- and food-reward homeostasis

Energy- and food-reward homeostasis is the essential component for maintaining energy balance and its disruption may lead to metabolic disorders, including obesity and diabetes. Circadian alignment, quality sleep and sleep architecture in relation to energy- and food-reward homeostasis are crucial. A reduced sleep duration, quality sleep and rapid-eye movement sleep affect substrate oxidation, leptin and ghrelin concentrations, sleeping metabolic rate, appetite, food reward, hypothalamic-pituitary-adrenal (HPA)-axis activity, and gut-peptide concentrations, enhancing a positive energy balance. Circadian misalignment affects sleep architecture and the glucose-insulin metabolism, substrate oxidation, homeostasis model assessment of insulin resistance (HOMA-IR) index, leptin concentrations and HPA-axis activity. Mood disorders such as depression occur; reduced dopaminergic neuronal signaling shows decreased food reward. A good sleep hygiene, together with circadian alignment of food intake, a regular meal frequency, and attention for protein intake or diets, contributes in curing sleep abnormalities and overweight/obesity features by preventing overeating; normalizing substrate oxidation, stress, insulin and glucose metabolism including HOMA-IR index, and leptin, GLP-1 concentrations, lipid metabolism, appetite, energy expenditure and substrate oxidation; and normalizing food reward. Synchrony between circadian and metabolic processes including meal patterns plays an important role in the regulation of energy balance and body-weight control. Additive effects of circadian alignment including meal patterns, sleep restoration, and protein diets in the treatment of overweight and obesity are suggested.

Sweetness, satiation, and satiety

Satiation and satiety are central concepts in the understanding of appetite control and both have to do with the inhibition of eating. Satiation occurs during an eating episode and brings it to an end. Satiety starts after the end of eating and prevents further eating before the return of hunger. Enhancing satiation and satiety derived from foodstuffs was perceived as a means to facilitate weight control. Many studies have examined the various sensory, cognitive, postingestive, and postabsorptive factors that can potentially contribute to the inhibition of eating. In such studies, careful attention to study design is crucial for correct interpretation of the results. Although sweetness is a potent sensory stimulus of intake, sweet-tasting products produce satiation and satiety as a result of their volume as well as their nutrient and energy content. The particular case of energy intake from fluids has generated much research and it is still debated whether energy from fluids is as satiating as energy ingested from solid foods. This review discusses the satiating power of foods and drinks containing nutritive and nonnutritive sweeteners. The brain mechanisms of food reward (in terms of "liking" and "wanting") are also addressed. Finally, we highlight the importance of reward homeostasis, which can help prevent eating in the absence of hunger, for the control of intake.

Satiety scores and satiety hormone response after sucrose-sweetened soft drink compared with isocaloric semi-skimmed milk and with non-caloric soft drink: a controlled trial

BACKGROUND/OBJECTIVES

Observational studies indicate that sugar-sweetened soft drinks (SSSD) may promote obesity, among other factors, owing to low-satiating effects. The effect of energy in drinks on appetite is still unclear. We examined the effect of two isocaloric, but macronutrient, different beverages (SSSD versus semi-skimmed milk) and two non-energy-containing beverages (aspartame-sweetened soft drink (ASSD) and water) on appetite, appetite-regulating hormones and energy intake (EI).

SUBJECTS/METHODS

In all, 24 obese individuals were included in a crossover trial. Each subject was served either 500 ml of SSSD (regular cola: 900 kJ), semi-skimmed milk (950 kJ), ASSD (diet cola: 7.5 kJ), or water. Subjective appetite scores, ghrelin, GLP-1, and GIP concentrations were measured at baseline and continuously 4-h post intake. Ad libitum EI was measured 4 h after intake of the test drinks.

RESULTS

Milk induced greater subjective fullness and less hunger than regular cola (P<0.05). Also, milk led to 31% higher GLP-1 (95% CI: 20, 44; P<0.01) and 45% higher GIP (95% CI: 23, 72; P<0.01) concentrations compared with SSSD. Ghrelin was equally 20% lower after milk and SSSD compared with water. The total EI (ad libitum EI+EI from the drink) was higher after the energy-containing drinks compared with diet cola and water (P<0.01).

CONCLUSIONS

Milk increased appetite scores and GLP-1 and GIP responses compared with SSSD. The energy containing beverages were not compensated by decreased EI at the following meal, emphasizing the risk of generating a positive energy balance by consuming energy containing beverages. Furthermore, there were no indications of ASSD increased appetite or EI compared with water.

Exercise prior to a freely requested meal modifies pre and postprandial glucose profile, substrate oxidation and sympathovagal balance

Background

The effects of exercise on glucose and metabolic events preceding and following a freely initiated meal have never been assessed. Moreover, the relationship between these events and sympathovagal balance is not known. The objective of this study was to determine whether exercise prior to a freely requested meal modifies the pre- and postprandial glucose profile, substrate oxidation and sympathovagal balance.

Methods

Nine young active male subjects consumed a standard breakfast (2298 ± 357 kJ). After 120 min, they either performed 75 min of exercise on a cycle ergometer (EX - 70% VO_2max) or rested (RT). Lunch was freely requested but eaten ad libitum only during the 1^st session, and then energy intake was fixed across conditions. Glucose and sympathovagal balance were assessed continuously using a subcutaneous glucose monitoring system and analysis of heart rate variability, respectively. Every 5 min, a mean value was calculated for both glucose and sympathovagal balance. Substrate oxidation was determined by calculating the gas exchange ratio when lunch was requested and 180 min after the onset of eating.

Results

Preprandial glucose profiles were found in 72% of the sessions and with a similar frequency under both conditions. Meals were requested after a similar delay (40 ± 12 and 54 ± 10 min in EX and RT respectively; ns). At meal request, sympathovagal balance was not different between conditions but CHO oxidation was lower and fat oxidation higher in EX than in RT (-46% and +63%, respectively; both p < 0.05). Glucose responses to the meal were higher in incremental (+ 48%) but not in absolute value in EX than in RT, with a higher fat oxidation (+ 46%, p < 0.05), and a greater vagal withdrawal (+ 15%, p < 0.05).

Conclusions

These results show that exercise does not impair preprandial glucose declines at the following meal freely requested, but leads to an increased postprandial glucose response and an elevated fat oxidation, an effect that vagal withdrawal may contribute to explain.

Substrate metabolism, appetite and feeding behaviour under low and high energy turnover conditions in overweight women

The present study aimed to investigate whether substrate metabolism, appetite and feeding behaviour differed between high and low energy turnover conditions. Thirteen overweight premenopausal women completed two 1 d trials: low energy turnover (LET) and high energy turnover (HET), in a randomised, cross-over design. In LET, subjects consumed a test breakfast (49 % carbohydrate, 37 % fat, 14 % protein) calculated to maintain energy balance over a 6 h observation period, during which metabolic rate and substrate utilisation were measured and blood samples taken. Immediately following this anad libitumbuffet meal was provided. HET was identical to LET, except that subjects walked on a treadmill for 60 min at 50 % VO2maxbefore the test breakfast, which was increased in size (by about 65 %) to replace the energy expended during the walk and maintain energy balance over the observation period. Postprandial fat balance (i.e. the difference between fat intake and oxidation) was lower and carbohydrate balance higher in HET compared with LET throughout the postprandial period (P < 0·05 for both). After the buffet meal, carbohydrate balance did not differ between trials but energy and fat balances were lower (by 0·28 MJ and 11·6 g, respectively) in HET compared with LET (P < 0·001 for both). Carbohydrate balance immediately before the buffet meal correlated negatively with buffet energy intake (r− 0·49) and postprandial acylated ghrelin responses (r− 0·48), and positively with postprandial glucose responses (r0·49). These findings demonstrate that HET resulted in a more positive carbohydrate balance than LET, which associated with lower subsequent energy intake. This may have implications for the regulation of body weight.

Comparison of the effects of a liquid yogurt and chocolate bars on satiety: a multidimensional approach

In the context of epidemic obesity, satiety is an important target for nutritional interventions. Using a multidimensional approach, we compared the effect on satiety of two food products frequently consumed in France by young adults as a small mid-afternoon meal called the ‘goûter’. Participants were eighteen healthy young males (aged 20·8 (sd1·8) years) of normal body weight (BMI 21·7 (sd1·7) kg/m2) used to eating four times per d including a ‘goûter’. On two occasions, under laboratory conditions, the time-blinded participants consumed a fixed energy lunch (2·8 MJ) and, 240 min later, either a liquid yogurt or chocolate bars matched for energy (1·2 MJ) and weight (366 g). Then, satiety was assessed by: (1) ratings of hunger, appetite, desire to eat and fullness at 20 min intervals (perception), (2) the delay until the subject requested his dinner meal (duration) and (3) energy intake at this meal (consumption). Results showed that satiety was perceived higher after liquid yogurt than chocolate bars over the 60 min preceding the next meal, as evidenced by hunger (P < 0·005), appetite, (P < 0·005), desire to eat (P < 0·04) and fullness (P < 0·05) ratings. However, its duration was similar between liquid yogurt and chocolate bars (165 (se8) and 174 (se7) min respectively) and this difference was not followed by reduced intake at dinner. In conclusion, this approach of satiety revealed that a liquid yogurt induced a lower subjective motivation to eat than chocolate bars during the hour preceding the spontaneous onset of a meal, without affecting subsequent food intake.

Impact of high-fat /low-carbohydrate, high-, low-glycaemic index or low-caloric meals on glucose regulation during aerobic exercise in Type 2 diabetes

AIMS

A decrement in blood glucose (BG) may be observed in patients with Type 2 diabetes (T2DM) when exercise is performed after a meal, in contrast to fasting. We determined the impact of different pre-exercise meal macronutrient compositions with modulation of the glycaemic index (GI) on glucose regulation during exercise in patients with T2DM.

METHODS

Using a randomized, single-blind crossover design, 10 sedentary men performed five exercise sessions, once after an overnight fast, and also after each of four test meals, consisting of a high-fat/low-carbohydrate meal, a high-GI meal, a low-GI meal, and a low-calorie meal.

RESULTS

Pre-exercise BG and insulin levels were comparable for all four meals. Exercise decreased BG and insulin levels during all meal conditions (all P < 0.001) compared with the fasting state in which BG levels did not change. The magnitude of BG and insulin decrements was similar after consuming the low-calorie, the high-GI and the high-fat/low-carbohydrate meals, whereas the low-GI meal induced the lowest BG fall. Adrenaline response was higher after consumption of the high-, the low-GI and the low-caloric meals compared with the high-fat/low-carbohydrate meal and with the fasting state (P < 0.05).

CONCLUSIONS

This study underlines the beneficial effect of low-GI foods and the differential impact of pre-exercise meal macronutrient composition on BG decrease. This may protect against exercise-induced hypoglycaemia, and reiterates the safety of exercising while fasting in T2DM patients.

Acute effects of pharmacological modifications of fatty acid metabolism on human satiety

The role of NEFA in eating behaviour is still poorly known. Our objective was to examine whether etomoxir (ETO), an inhibitor of NEFA oxidation, or ( − )-hydroxycitrate (HCA), an inhibitor of lipogenesis which may indirectly stimulate NEFA oxidation, alters satiety. Post-lunch satiety was measured in eight normal-weight male subjects who were deprived of time cues and received on three occasions either ETO (320 mg), HCA (2 g) or placebo (PLA) in random order. Between lunch and dinner, blood was withdrawn continuously and collected every 10 min for measures of plasma concentrations of glucose, insulin, lactate, TAG, NEFA, β-hydroxybutyrate (BHB), leptin and ghrelin. Results showed that HCA began to decrease hunger and desire to eat compared to PLA and ETO 210 min after lunch and increased satiety duration compared to PLA by 70 (se23) min (P < 0·05), but did not modify energy intake at dinner. ETO did not affect any variable of satiety. HCA increased NEFA concentrations during the pre-dinner period, whereas ETO increased and decreased plasma concentrations of NEFA and BHB, respectively. Mean differences in plasma NEFA concentrations between HCA and PLA were predictive of the differences in satiety duration between treatments (r20·71,P < 0·01). Among treatments, plasma leptin concentration at dinner onset was the only blood variable correlated with energy intake at this meal (r− 0·75,P < 0·0005). In healthy, normal-weight men, acute HCA increased the intensity and duration of satiety possibly via increased NEFA disposal for oxidation.

The glucostatic theory of appetite control and the risk of obesity and diabetes

More than 50 years ago, Jean Mayer proposed that changes in blood glucose concentrations or arteriovenous glucose differences are detected by glucoreceptors that affect energy intake. According to this theory, an increase in blood glucose concentrations results in increased feelings of satiety whereas a drop in blood glucose concentrations has the opposite effect. The pioneering work of Mayer has recently received support from our group as low glycemia has been shown to be linked with body weight gain prospectively and has been considered as a strong predictor of the amount of weight regained after weight loss. This state of mild hypoglycemia also predicts the increase in depressive symptoms with weight loss and a greater propensity to glucose intolerance and type 2 diabetes, particularly for individuals having short sleep durations. Furthermore, knowledge-based work has been shown to induce a significant increase in spontaneous energy intake being related to changes in glycemic control. In accordance with the glucostatic theory, this oriented review suggests that factors favoring a trend toward hypoglycemia and/or glucose instability might induce excess energy intake, overweight and impaired glucose tolerance. Data also raise the possibility that fat gain might be protective against mild hypoglycemia by providing compensation to the stimuli promoted by a modern environment.

A high-glycemic meal pattern elicited increased subjective appetite sensations in overweight and obese women

We examined the effects of variations in postprandial glycemia and insulinemia on subjective satiety in overweight and obese women. We altered the ingestion rate of a glucose beverage to model the postprandial effects of high- and low-glycemic meals. Fourteen women were tested in a within-subjects' design with two conditions: (1) Rapid, with a large glucose beverage consumed with breakfast and lunch and (2) Slow, with the same volume of glucose beverage consumed in eight portions (one with each meal, and the remaining seven at 20-min intervals after each meal). Meals were identical in the two conditions. Subjective appetitive sensations were measured with visual analog scales before and after meals, and hourly after each meal until 5 pm. Serum glucose and insulin were measured at similar time points. Subjects reported higher ratings of hunger and prospective consumption in the Rapid versus Slow condition at 4h after breakfast and several hours after lunch. Serum glucose was more strongly correlated with the appetitive ratings in the Rapid than the Slow condition, and explained more of the variance (20-31%) than insulin (2-4%). The results of this study support the glucostatic theory linking dynamic changes in blood glucose with appetitive sensations.

Glucose homeostasis predicts weight gain: prospective and clinical evidence

BACKGROUND

The potential long-term impact of low glycaemia on body fat accumulation has not been verified. Therefore, we examined the effects of low glucose concentrations on long-term energy balance and weight gain in humans.

METHODS

Two sets of analyses were realized in order to verify this objective. First, Study 1 consisted of 259 participants between 20 and 65 years of age selected from Phase 2 of the Quebec Family Study (QFS). The association between glucose concentrations at the end of an oral glucose tolerance test (OGTT) and changes in body mass was analysed prospectively (mean follow-up of 6 years). In addition, Study 2 consisted of 44 obese participants (20 men and 24 women) randomly assigned to a 15-week weight loss program in either a drug therapy group (fenfluramine) or a placebo group coupled with energy intake restriction. The focus of this study was the relationship between glycaemic control at the end of the treatment and post-treatment weight regain.

RESULTS

In Study 1, the glucose concentrations at 120 min of the OGTT were negatively correlated with weight gain over 6 years (r=-0.42, p<0.01). In Study 2, the weight loss program induced a mean reduction in body weight of 10 kg in the fenfluramine and placebo groups. In participants who returned for a follow-up visit (mean=81 weeks after the intervention), the glucose area below fasting values (GABF) at the end of the OGTT increased with weight loss (p<0.01) and was correlated with weight regain (r=0.74, p<0.01).

CONCLUSIONS

Lower glucose concentrations at the end of an OGTT are correlated with weight gain over time. Large amounts of weight loss are associated with low glycaemia at the end of an OGTT. These low glucose concentrations are strong predictors of the amount of weight regained after weight loss.

No differences in satiety or energy intake after high-fructose corn syrup, sucrose, or milk preloads

BACKGROUND

It is unclear whether energy-containing drinks, especially those sweetened with high-fructose corn syrup (HFCS), promote positive energy balance and thereby play a role in the development of obesity.

OBJECTIVE

The objective was to examine the satiating effects of HFCS and sucrose in comparison with milk and a diet drink.

DESIGN

The effects of four 800-mL drinks [corrected] containing no energy or 1.5 MJ from sucrose, HFCS, or milk on satiety were assessed, first in 15 men and 15 women with a mean (+/-SD) body mass index (BMI; in kg/m(2)) of 22.1 +/- 1.9 according to visual analogue scales (VAS) and blood variables and second in 20 men and 20 women (BMI: 22.4 +/- 2.1) according to ingestion of a standardized ad libitum meal (granola cereal + yogurt, 10.1 kJ/g).

RESULTS

Fifty minutes after consumption of the 1.5-MJ preload drinks containing sucrose, HFCS, or milk, 170%-mm VAS changes in satiety were observed. Glucagon-like peptide 1 (GLP-1) (P < 0.001) and ghrelin (P < 0.05) concentrations changed accordingly. Compensatory energy intake did not differ significantly between the 3 preloads and ranged from 30% to 45%. Energy intake compensations were related to satiety (r = 0.35, P < 0.05). No differences were observed between the effects of the sucrose- and HFCS-containing drinks on changes in VAS and on insulin, glucose, GLP-1, and ghrelin concentrations. Changes in appetite VAS ratings were a function of changes in GLP-1, ghrelin, insulin, and glucose concentrations.

CONCLUSION

Energy balance consequences of HFCS-sweetened soft drinks are not different from those of other isoenergetic drinks, eg, a sucrose-drink or milk.

Association of sleep duration with type 2 diabetes and impaired glucose tolerance

AIMS/HYPOTHESIS

The aim of this study was to assess the relationship between sleep duration and type 2 diabetes or impaired glucose tolerance (IGT).

METHODS

Anthropometric measurements and self-reported sleep duration were determined in a cross-sectional sample of 323 men and 417 women aged 21-64 years from the Quebec Family Study. Glucose homeostasis indicators were compared between short (5-6 h), 'normal' (7-8 h) and long (9-10 h) sleeper groups.

RESULTS

Using adults with 7-8 h of sleep as a reference, the adjusted odds ratio for type 2 diabetes/IGT was 1.58 (1.13-2.31) for those with 9-10 h of sleep and 2.09 (1.34-2.98) for those with 5-6 h of sleep, after adjustment for potential confounding variables. The short and long sleepers presented significantly higher total insulin AUC (p < 0.05), whereas total glucose AUC was not different between the three sleeper groups in both sexes. The mean glucose area below fasting glucose concentrations was significantly higher in short (p < 0.01) and long sleepers (p < 0.05) compared with 'normal' sleepers, and significantly higher in short (p < 0.05) compared with long sleepers in both sexes.

CONCLUSIONS/INTERPRETATION

The present study provides evidence that short- and long-duration sleep times are associated with type 2 diabetes/IGT in adults, even after adjustment for several confounders. These results also showed that the lower glucose concentrations at the end of the OGTT were observed in short sleepers. According to the glucostatic theory of appetite control, this represents a stimulus that can trigger episodes of hunger and spontaneous food intake, which may explain at least in part the greater risk of overweight displayed by short sleepers, as shown in previous studies.

Effects of soft drink consumption on nutrition and health: a systematic review and meta-analysis

In a meta-analysis of 88 studies, we examined the association between soft drink consumption and nutrition and health outcomes. We found clear associations of soft drink intake with increased energy intake and body weight. Soft drink intake also was associated with lower intakes of milk, calcium, and other nutrients and with an increased risk of several medical problems (e.g., diabetes). Study design significantly influenced results: larger effect sizes were observed in studies with stronger methods (longitudinal and experimental vs cross-sectional studies). Several other factors also moderated effect sizes (e.g., gender, age, beverage type). Finally, studies funded by the food industry reported significantly smaller effects than did non-industry-funded studies. Recommendations to reduce population soft drink consumption are strongly supported by the available science.

Training to estimate blood glucose and to form associations with initial hunger

BACKGROUND

The will to eat is a decision associated with conditioned responses and with unconditioned body sensations that reflect changes in metabolic biomarkers. Here, we investigate whether this decision can be delayed until blood glucose is allowed to fall to low levels, when presumably feeding behavior is mostly unconditioned. Following such an eating pattern might avoid some of the metabolic risk factors that are associated with high glycemia.

RESULTS

In this 7-week study, patients were trained to estimate their blood glucose at meal times by associating feelings of hunger with glycemic levels determined by standard blood glucose monitors and to eat only when glycemia was < 85 mg/dL. At the end of the 7-week training period, estimated and measured glycemic values were found to be linearly correlated in the trained group (r = 0.82; p = 0.0001) but not in the control (untrained) group (r = 0.10; p = 0.40). Fewer subjects in the trained group were hungry than those in the control group (p = 0.001). The 18 hungry subjects of the trained group had significantly lower glucose levels (80.1 +/- 6.3 mg/dL) than the 42 hungry control subjects (89.2 +/- 10.2 mg/dL; p = 0.01). Moreover, the trained hungry subjects estimated their glycemia (78.1 +/- 6.7 mg/dL; estimation error: 3.2 +/- 2.4% of the measured glycemia) more accurately than the control hungry subjects (75.9 +/- 9.8 mg/dL; estimation error: 16.7 +/- 11.0%; p = 0.0001). Also the estimation error of the entire trained group (4.7 +/- 3.6%) was significantly lower than that of the control group (17.1 +/- 11.5%; p = 0.0001). A value of glycemia at initial feelings of hunger was provisionally identified as 87 mg/dL. Below this level, estimation showed lower error in both trained (p = 0.04) and control subjects (p = 0.001).

CONCLUSION

Subjects could be trained to accurately estimate their blood glucose and to recognize their sensations of initial hunger at low glucose concentrations. These results suggest that it is possible to make a behavioral distinction between unconditioned and conditioned hunger, and to achieve a cognitive will to eat by training.