Cross-talk between AMPK and mTOR in regulating energy balance

Energy balance is maintained by a complex homeostatic system involving some signaling pathways and "nutrient sensors" in multiple tissues and organs. Any defect associated with the pathways can lead to metabolic disorders including obesity, type 2 diabetes, and the metabolic syndrome. The 5'-adenosine monophosphate-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) appear to play a significant role in the intermediary metabolism of these diseases. AMPK is involved in the fundamental regulation of energy balance at the whole body level by responding to hormonal and nutrient signals in the central nervous system and peripheral tissues that modulate food intake and energy expenditure. Mammalian target of rapamycin (mTOR),is one of the downstream targets of AMPK functions as an intracellular nutrient sensor to control protein synthesis, cell growth, and metabolism. Recent research demonstrated the possible interplay between mTOR and AMPK signaling pathways. In this review, we will present current knowledge of AMPK and mTOR pathways in regulating energy balance and demonstrate the convergence between these two pathways.     

Effects of dietary polyphenols on neuroregulatory factors and pathways that mediate food intake and energy regulation in obesity

Polyphenols are natural substances and are enriched in vegetables, fruits, grains, bark, tea, and wine. Some polyphenols have insulin‐potentiating and anti‐inflammatory effects, both of which are important in obesity. Dietary supplementation with polyphenolic compounds is associated with reduced diet‐induced obesity and/or metabolic syndrome in animal and human studies. Insights into mechanisms that regulate food intake and satiety have led to an increased understanding of obesity but the pathogenesis underlying obesity is lacking. Food intake is subject to a complex regulation by the hypothalamus and other brain centers including the brain stem and the hippocampus. An intricate network of interacting feedback mechanisms that involve the aforementioned neural centers along with the stomach, gut, liver, thyroid, and adipose tissue in the periphery, influence the eventual outcome of food intake and satiety. Key peripheral signals, such as leptin, insulin, and ghrelin, have been linked to hypothalamic neuropeptide systems in energy regulation. This review will examine the neural centers important in food intake, the role of various neuropeptides, and the neurohormonal influence on food intake. The potential role of polyphenols in influencing the neuroregulatory factors, the neural signaling pathways and/or the peripheral feedback mechanisms that modulate food intake will also be examined.     

Obesity and sleep disturbance: the chicken or the egg?

Epidemiological studies suggested an association between obesity and sleep disturbances. Obstructive sleep apnea is the most prevalent type of obesity-related sleep disorder that lead to an increased risk for numerous chronic health conditions. In addition the increased visceral adipose tissue might be responsible for the secretion of inflammatory cytokines that could contribute to alter the sleep-wake rhythm. Unhealthy food characterized by high consumption of fat and carbohydrate seems to negatively influence the quality of sleep while diet rich of fiber is associated to more restorative and deeper sleep. Although obesity could cause through several pathogenetic mechanisms an alteration of sleep, it has been reported that subjects suffering from sleep disorders are more prone to develop obesity. Experimental laboratory studies have demonstrated that decreasing either the amount or quality of sleep increase the risk of developing obesity. Experimental sleep restriction also causes physiological, hormonal and food behavioral changes that promote a positive energy balance and a compensatory disproportionate increase in food intake, decrease in physical activity, and weight gain. Thus, the aim of this review is to provide observational evidence on the association of obesity with sleep disturbances and viceversa with emphasis on possible pathophysiological mechanisms (hormonal and metabolic) that link these two pathological conditions.     

Low-glycemic-load diets: impact on obesity and chronic diseases

Historically, carbohydrates have been thought to play only a minor role in promoting weight gain and in predicting the risk of development of chronic disease. Most of the focus had been on reducing total dietary fat. During the last 20 years, fat intake decreased, while the number of individuals who were overweight or developed a chronic conditions have dramatically increased. Simultaneously, the calories coming from carbohydrate have also increased. Carbohydrates can be classified by their post-prandial glycemic effect, called the glycemic index or glycemic load. Carbohydrates with high glycemic indexes and high glycemic loads produce substantial increases in blood glucose and insulin levels after ingestion. Within a few hours after their consumption, blood sugar levels begin to decline rapidly due to an exaggerated increase in insulin secretion. A profound state of hunger is created. The continued intake of high-glycemic load meals is associated with an increased risk of chronic diseases such as obesity, cardiovascular disease, and diabetes. In this review, the terms glycemic index and glycemic load are defined, coupled with an overview of short- and long-term changes that occur from eating diets of different glycemic indexes and glycemic loads. Finally, practical strategies for how to design low-glycemic-load diets consisting primarily of low-glycemic carbohydrates are provided.     

减盐、减油、减糖现状与工作对策

作为膳食的重要组成部分,盐、油、糖在满足人的口感与营养的同时,过多摄入可能导致高血压、肥胖、糖尿病、心脑血管疾病等慢性病.减盐、减油、减糖是控制慢性病最经济、最有效的手段,只有政府、企业、专家、媒体等社会各界共同发力,营造良好支持环境,从供给侧、需求侧方面均落实减盐、减油、减糖措施,才能全面遏制慢性病流行的态势.     

我国3岁及以上城市居民焙烤食品消费量及其游离糖摄入评估

目的 了解我国3岁及以上城市居民焙烤食品消费量、来源于焙烤食品游离糖摄入量及其供能比。方法采用多阶段分层与人口成比例的整群随机抽样方法,在我国18个省,采用非连续3天24小时回顾方法,收集13 083名3岁及以上城市居民的焙烤食物消费量。焙烤食品糖含量数据来源于国家食品安全风险评估中心开展的焙烤食品专项监测数据。采用简单分布评估方法计算我国3岁及以上城市居民通过焙烤食品的糖摄入量及供能比。结果 我国3岁及以上城市居民(一般人群)的焙烤食品消费率为24.11%,女性略高于男性,分别为25.69%和22.42%。随年龄增加,各年龄组焙烤食品消费率总体呈下降趋势,3～5岁组最高为39.09%,60岁以上组最低,为17.57%。一般人群焙烤食品平均消费量为10.25 g/d,女性(10.58 g/d)略高于男性(9.92 g/d);各年龄组焙烤食品平均消费量最高为13～17岁组(16.36 g/d),6～12岁组和3～5岁组次之,分别为15.22 g/d和13.25 g/d。一般人群通过焙烤食品游离糖的平均摄入量为1.54 g/d,平均供能比为0.37%(0.37%TE),女性(1.60 g/d,0.41%TE)高于男性(1.47 g/d,0.33%TE);各年龄组,13～17岁组游离糖摄入量最高,为2.21 g/d(0.52%TE),6～12岁组和3～5岁组摄入量次之,分别为2.14 g/d(0.59%TE)和1.94 g/d(0.65%TE)。焙烤食品消费人群平均供能比为1.53%TE(1.43%TE～1.67%TE),焙烤食品消费人群的高消费者(P₉₅)为3.86%。一般人群,通过面包和糕点摄入的游离糖平均值分别为0.68 g/d和0.73 g/d,远高于饼干(0.13 g/d)。结论 我国3岁及以上城市居民一般人群,女性的焙烤食品消费率、游离糖摄入量、游离糖供能比均高于男性,通过焙烤食品摄入的游离糖水平较低。焙烤食品减糖时,建议重点关注3～5岁、6～12岁、13～17岁人群,重点关注面包和糕点这两类食品。     

Why Sugar Is Added to Food: Food Science 101

Avoiding too much sugar is an accepted dietary guidance throughout the world. The U.S. Nutrition Facts panel includes information on total sugars in foods. A focus on added sugars is linked to the concept of discretionary calories and decreasing consumption of added sugars or free sugars as a means to assist a consumer to identify foods that are nutrient‐dense. On March 14, 2014, the U.S. Food and Drug Administration proposed that including “added sugars” declaration on the Nutrition Facts panel would be another tool to help consumers reduce excessive discretionary calorie intake from added sugars. Through deductive reasoning, labeling added sugars is one tactic to potentially curb the obesity epidemic in the United States. This review discusses the functions of sugar in food and shows that the methods used to replace added sugars in foods can result in no reduction in calorie content or improvement in nutrient density. Without clear benefit to the consumer for added sugars labeling, this review highlights the complex business obstacles, costs, and consumer confusion resulting from the proposed rule.     

我国3岁及以上城市居民含糖饮料消费状况及其游离糖摄入评估

目的 了解我国3岁及以上城市居民含糖饮料消费状况,评估含糖饮料的游离糖摄入量及其供能比.方法 采用多阶段分层与人口成比例的整群随机抽样方法,在我国18个省(自治区、直辖市),采用非连续3 d 24 h回顾调查方法,收集13 083名3岁及以上城市居民的各类食物包括含糖饮料的消费量.含糖饮料游离糖的含量数据来源于国家食品...     

Symposium review: Fueling appetite: Nutrient metabolism and the control of feed intake

Conceptual models developed over the past century describe 2 key constraints to feed intake (FI) of healthy animals: gut capacity and metabolic demand. Evidence that greater energy demands (e.g., greater milk production) drive a corresponding increase in caloric intake led to the dominant concept that animals “eat to energy requirements.” Although this model provides reasonable initial estimates of FI, it lacks a proposed physiological basis for the control system, does not consider nutrient constraints beyond energy, and fails to explain differential energy intake responses to different fuels. To address these gaps, research has focused on mechanisms for sensing nutrient availability and providing feedback to hypothalamic centers that integrate signals to control feeding behavior. The elimination of FI response to certain nutrients by vagotomy suggests that peripheral tissues play a role in nutrient sensing. These findings and the central role of the liver in metabolic flux led to the development of the hepatic oxidation theory (HOT). According to the HOT, liver energy charge is the regulated variable that induces dietary intake changes and consequently affects whole-body energy balance. Evidence in support of HOT includes associations between hepatic energy charge and meal patterns, increased FI in response to phosphate trapping, and reduced FI in response to phosphate loading. In accordance with the HOT, infusion studies in dairy cattle have consistently demonstrated that providing fuels that either oxidize or stimulate oxidation in the liver decreases FI and energy intake to a greater extent than fuels that bypass the liver. Importantly, this holds true for glucose, which is readily oxidized by nerve cells, but is rarely taken up by the bovine liver. Although the brain integrates multiple signals including those related to gastric distention and illness, the HOT provides a physiological framework for understanding the dominant role the liver likely plays in sensing short-term energy status. Understanding this model provides insights into how to use or bypass the regulatory system to manage FI of animals.     

Women, nutrition and exercise: a review of athletes' intakes and a discussion of energy balance in active women

Given the heightened interest in nutritional aspects of exercise, and an increase in athletic participation by women, it appeared timely to review the nutritional implications of exercise in women. The initial part of this paper contains a compilation of published studies on the nutrient intakes of female athletes. These reveal that most groups of athletes have adequate nutrient intakes, and that their vitamin and mineral intakes appear to be superior to those of nonathletic women. The average energy intake of athletes in studies summarized in this paper was 2069 kcal, and for certain groups of athletes, energy intakes were even lower. How these women manage to train intensely while consuming energy intakes similar to those of sedentary women is not readily apparent, and for this reason, the remainder of the paper discusses energy balance as affected by activity. Methodological considerations related to assessment of the components of the energy balance equation (food intake, energy expenditure, and body energy stores) are presented, with a focus on considerations in women. The effects of activity on each of these components are then discussed in an attempt to determine whether some form of energy conservation may occur. Finally, effects of activity on the menstrual cycle are reviewed. The observed changes are discussed in relation to nutrition 1) in terms of how nutrition may play a role in their causation; and 2) in terms of their nutritional implications for the amenorrheic athlete, specifically as regards energy balance and bone density.     

Impact of 100% Fruit Juice Consumption on Diet and Weight Status of Children: An Evidence-based Review

Consumption of 100% fruit juice remains controversial for its potential adverse impact on weight and displacement of essential foods in the diets of children. A systematic review of the literature published from 1995–2013 was conducted using the PubMed database to evaluate associations between intake of 100% fruit juice and weight/adiposity and nutrient intake/adequacy among children of 1 to 18 years of age. Weight status outcome measures included body mass index (BMI), BMI z-score, ponderal index, obesity, weight gain, adiposity measures, and body composition. Nutrient outcome measures included intake and adequacy of shortfall nutrients. Data extraction and analysis was conducted according to the Academy of Nutrition and Dietetics Evidence Analysis Process. Twenty-two studies on weight status provided evidence that did not support an association between 100% fruit juice consumption and weight/adiposity in children after controlling for energy intake. Limited evidence from eight studies suggests that children consuming 100% fruit juice have higher intake and adequacy of dietary fiber, vitamin C, magnesium, and potassium. Differences in methodology and study designs preclude causal determination of 100% fruit juice as sole influencer of weight status or nutrient intake/adequacy of shortfall nutrients. In context of a healthy dietary pattern, evidence suggests that consumption of 100% fruit juice may provide beneficial nutrients without contributing to pediatric obesity.     

Sensory Perception,Nutritional Role,and Challenges of Flavored Milk for Children and Adults

Milk and milk products provide essential nutrients for both adults and children. However, overall milk consumption of both adults and children does not meet the recommendations from Dietary Guidelines for Americans. Flavored milk can increase milk consumption for children and adolescents, but the added sugar content raises concern. Since the removal or reduction of flavored milk decreases milk consumption for children, it is important to understand all aspects of flavored milk in order to increase milk consumption while minimizing sugar intake. This review will address adult and children perception of flavored milk as well as its nutrition, regulations in school meal programs, and challenges. Understanding the sensory perception of both adults and children for flavored milk can help food developers and manufacturers to address attractive attributes while reducing the sugar content to meet the needs of a healthy diet.     

Dietary D-psicose reduced visceral fat mass in high-fat diet-induced obese rats

D-Psicose, a C-3 epimer of D-fructose, has shown promise in reducing body fat accumulation in normal rats and plasma glucose level in genetic diabetic mice. Effects of D-psicose on diet-induced obesity are not clearly elucidated, and we investigated food intake, body weight, and fat accumulation in rats fed high-fat (HF) diet. Sprague-Dawley rats became obese by feeding HF diet for 4 wk, and were assigned either to normal or HF diet supplemented with or without D-psicose, sucrose, or erythritol for 8 wk. Changing HF to normal diet gained less body weight and adipose tissue due to different energy intake. D-psicose-fed rats exhibited lower weight gain, food efficiency ratio, and fat accumulation than erythritol- and sucrose-fed rats. This effect was more prominent in D-psicose-fed rats with normal diet than with HF diet, suggesting combination of psicose and calorie restriction further reduced obesity. There was no difference in serum cholesterol/high-density lipoprotein (HDL)-C and low-density lipoprotein (LDL)-C/HDL-C ratios between D-psicose group and other groups. Liver weight in 5% psicose group with normal diet was higher than in other groups, but histopathological examination did not reveal any psicose-related change. D-Psicose inhibited the differentiation of mesenchymal stem cell (MSC) to adipose tissue in a concentration-dependent manner. These results demonstrate that D-psicose produces a marked decrease, greater than erythritol, in weight gain and visceral fat in an established obesity model by inhibiting MSC differentiation to adipocyte. Thus, D-psicose can be useful in preventing and reducing obesity as a sugar substitute and food ingredient. PRACTICAL APPLICATION: We can develop D-psicose as a sugar substitute and food ingredient since it can prevent obesity in normal people, but also suppress adiposity as a sugar substitute or food ingredients with antiobesity effect in obese people. D-psicose can be unique functional sweetener because of its function of reducing visceral fat mass and weight gain.     

Pecan nuts: A review of reported bioactivities and health effects

BackgroundFood choices represent a highly significant approach to combat human obesity. Dietary intake of lipids, especially polyunsaturated and monounsaturated fatty acids, is gaining popularity in the effort to reduce or eliminate the occurrence of obesity. Pecan (Carya illinoinensis) nuts are an abundant source of these dietary fatty acids. Moreover, they are a rich source of epigallocatechin-3-gallate (EGCG), a polyphenol with a variety of health-beneficial properties.Scope and approachIn this review, we summarize the literature reports examining physiological effects associated with pecan nuts consumption and described effects of their bioactive constituents.Key findings and conclusionsThe growing body of evidence suggests including pecan nuts into obesity management strategies. The consumption of pecan nuts can mitigate inflammation by reducing the extent of the synthesis of inflammatory mediator molecules. Pecan nuts can also counteract the pro-inflammatory effects of a diet rich in commonly overconsumed saturated fatty acids, characteristic of the Western diet. Additionally, consumption of pecans and other nuts has been linked to reduced risk of physiological parameters associated with cardiovascular disease or metabolic disorders. Diets enriched with tree nuts and peanuts can modulate the blood level of cholesterol, adiposity, and insulin resistance. Almonds and walnuts have been so far the most studied nuts, and studies with them have led to a greater understanding of the protective effects of diverse tree nuts on human physiology. In this review, we summarize the available data indicating that pecan nuts exert similar health-promoting benefits.     

膳食纤维减肥功效的机理探讨

综述了最新的关于膳食纤维在减肥方面的研究，包括膳食纤维如何能帮助体重下降以及保持体重的潜在机制。通过流行病学的研究发现，膳食纤维的摄入对预防肥胖有很大的功效，对人体健康有积极作用。     

Invited review: effects of milk ration on solid feed intake, weaning, and performance in dairy heifers

A feeding regimen that allows a smooth transition from milk to solid feed is vital for successful heifer-rearing programs. In the past, research efforts have focused on the development of feeding methods that allow early weaning, perhaps because the risk of disease is highest during the milk feeding stage. To encourage early intake of calf starter, conventional feeding programs have limited the supply of milk (often to 10% of BW at birth). However, dairy calves provided free access to milk will typically consume more than twice this amount. We critically review the available literature examining the relationship between milk feeding method, solid feed consumption, and rumen development in young dairy calves and identify areas where new work is required. We conclude that milk-fed dairy calves can safely ingest milk at approximately 20% of body weight (BW)/d, and greater milk consumption supports greater BW gain, improved feed efficiency, reduced incidence of disease, and greater opportunity to express natural behaviors, which in combination suggest improved welfare. Method of weaning greatly influences feed consumption, rumen development, and growth check in calves provided higher amounts of milk. Gradual weaning encourages starter intake during the preweaning period, and both weaning age and duration of weaning influence this consumption. Increased solid feed consumption during the weaning process contributes to rumen development, permitting higher starter intake and BW gain after weaning. Growth factors in milk may also enhance the growth and maturation of the gastrointestinal tract, but more research is required to understand the role of these factors. Greater nutrient supply through increased amount of milk appears to improve immune function and long-term performance of heifer calves; for example, reducing the age at first breeding and increasing first-lactation milk yield, but more research is needed to confirm these effects.     

External cues challenging the internal appetite control system—Overview and practical implications

Inadequate regulation of food intake plays an important role in the development of overweight and obesity, and is under the influence of both the internal appetite control system and external environmental cues. Especially in environments where food is overly available, external cues seem to override and/or undermine internal signals, which put severe challenges on the accurate regulation of food intake. By structuring these external cues around five different phases in the food consumption process this paper aims to provide an overview of the wide range of external cues that potentially facilitate or hamper internal signals and with that influence food intake. For each of the five phases of the food consumption process, meal initiation, meal planning, consumption phase, end of eating episode and time till next meal, the most relevant internal signals are discussed and it is explained how specific external cues exert their influence.     

Obesity. The food research agenda

It is estimated that almost 287 million children will be obese by 2010, and the overall obese population could rise to 700 million by 2015. The metabolic syndrome is a condition characterized by central obesity, hypertension, and disturbed glucose and insulin metabolism, and has been linked to increased risk of both type 2 diabetes and cardiovascular diseases. Diet, socioeconomic, and lifestyle factors have a central role to play in the obesity epidemic. In this respect, the role of particular dietary components on satiety and regulation of food and energy intake, are discussed as are technological approaches to manufacture of foods with low obesigenicity.     

Tea, obesity, and diabetes

Tea has been found to possess widespread biological functions based on a variety of laboratory data. The effects of tea on obesity and diabetes have received increasing attention. This paper reviews the evidence for the connections among tea catechins, and obesity and diabetes. Tea catechins, especially (-)-epigallocatechin gallate (EGCG), appear to have antiobesity and antidiabetic effects. While few epidemiological and clinical studies show the health benefits of EGCG on obesity and diabetes, the mechanisms of its actions are emerging based on the various laboratory data. These mechanisms may be related to certain pathways, such as through the modulations of energy balance, endocrine systems, food intake, lipid and carbohydrate metabolism, the redox status, and activities of different types of cells (i. e., fat, liver, muscle, and beta-pancreatic cells). Because the EGCG receptor, the so-called 67-kDa laminin receptor (LR), has been discovered with colocalization of other types of LR and cytoskeleton in both cancer cells and normal cells, this may explain that EGCG possesses numerous actions. The mechanistic results of this review may possibly be utilized in the treatment of obesity, diabetes, and other related diseases using tea- and EGCG-based folk medicines.     

The role of taste in alcohol preference,consumption and risk behavior

Alcohol consumption is widespread, and high levels of use are associated with increased risk of developing an alcohol use disorder. Thus, understanding the factors that influence alcohol intake is important for disease prevention and management. Additionally, elucidating the factors that associate with alcohol preference and intake in non-clinical populations allows for product development and optimisation opportunities for the alcoholic beverage industry. The literature on how taste (orosensation) influences alcohol behavior is critically appraised in this review. Ethanol, the compound common to all alcoholic beverages, is generally aversive as it primarily elicits bitterness and irritation when ingested. Individuals who experience orosensations (both taste and chemesthetic) more intensely tend to report lower liking and consumption of alcoholic beverages. Additionally, a preference for sweetness is likely associated with a paternal history of alcohol use disorders. However, conflicting findings in the literature are common and may be partially attributable to differences in the methods used to access orosensory responsiveness and taste phenotypes. We conclude that while taste is a key driver in alcohol preference, intake and use disorder, no single taste-related factor can adequately predict alcohol behaviour. Areas for further research and suggestions for improved methodological and analytical approaches are highlighted.