Inverse association between the effect of carbohydrates on blood glucose and subsequent short-term food intake in young men

BACKGROUND: A primary mechanism by which carbohydrates are thought to regulate satiety and food intake is through their effect on blood glucose. OBJECTIVES: The objectives were to describe the effect of defined carbohydrate preloads on food intake and blood glucose and to determine the association between food intake and blood glucose. DESIGN: Three experiments were conducted in which selected carbohydrates as 1255-kJ isovolumetric beverages were administered to young men after an overnight fast. Measurements of blood glucose and appetite were made at specified times during the next 60 min. Food intake was measured at 60 min. RESULTS: Glucose resulted in the highest glycemic response, which was followed, in order, by the responses to polycose, sucrose, amylopectin, a fructose-glucose mixture, and amylose. The high-glycemic-index preloads (glucose, polycose, and sucrose) resulted in lower mealtime energy intake during a test meal at 1 h, but the low-glycemic-index preloads (amylose, amylopectin, and a fructose-glucose mixture) did not. An inverse relation was observed between the blood glucose concentrations in the area under the curve and the subjective appetite (r = -0.23, P < 0.05) and food intake at 60 min (r = -0.24, P < 0.05). CONCLUSIONS: Food intake and subjective appetite are inversely associated with blood glucose response in the 60 min after consumption of carbohydrates. Carbohydrates with a high glycemic index (glucose, polycose, and sucrose) suppress subjective appetite and food intake in the short term, but those with a low glycemic index (amylose and amylopectin) do not.     

Carbohydrates and increases in obesity: does the type of carbohydrate make a difference?

With the prevalence of obesity increasing in the U.S. and elsewhere, the place of carbohydrates in the diet has recently been under closer examination. This has led to the development of methods for analyzing the effects of dietary carbohydrate. Primary among these methods is the glycemic index, a measure of a food's effect on blood glucose levels, which was initially designed as a method for determining suitable carbohydrates for people with diabetes. However, the glycemic index does not address other metabolic issues related to excess sugar consumption. Prominent among these issues is the use of low glycemic index sweeteners, particularly fructose, which is increasingly present in processed food. Fructose is associated with increased adiposity, which may result from its effects on hormones associated with satiety. Other methods of determining "good" carbohydrates have also been developed. The common theme among them is increased nonstarchy vegetables and higher-fiber legumes.     

Carbohydrate and satiety

This review focuses on what is known about the effects of carbohydrate on food intake, the potential mechanisms mediating these effects, and the impact of different monosaccharides in humans. The inhibition of subsequent food intake associated with ingestion of carbohydrate appears to result primarily from gastrointestinal signals, including those generated by orosensory stimulation, gastric distension, and perhaps most importantly the interaction of nutrients with receptors in the small intestine. The latter is associated with the release of putative satiety hormones, including glucagon-like peptide-1 and amylin, and slowing of both gastric emptying and small intestinal transit (thereby prolonging gastric distension and increasing the time available for nutrient absorption). The effects of carbohydrate on food intake are dependent on the route of administration (i.e., oral, intragastric, or intraduodenal). Changes in blood glucose and insulin concentrations per se probably do not play a major role in the induction of satiety. Studies relating to the comparative effects of different monosaccharides/carbohydrates have yielded inconclusive results, probably in part owing to substantial differences in methodological approaches.     

Glycemic index in chronic disease: a review

AIM: The intent of this review is to critically analyze the scientific evidence on the role of the glycemic index in chronic Western disease and to discuss the utility of the glycemic index in the prevention and management of these disease states. BACKGROUND: The glycemic index ranks foods based on their postprandial blood glucose response. Hyperinsulinemia and insulin resistance, as well as their determinants (eg high energy intake, obesity, lack of physical activity) have been implicated in the etiology of diabetes, coronary heart disease and cancer. Recently, among dietary factors, carbohydrates have attracted much attention as a significant culprit, however, different types of carbohydrate produce varying glycemic and insulinemic responses. Low glycemic index foods, characterized by slowly absorbed carbohydrates, have been shown in some studies to produce beneficial effects on glucose control, hyperinsulinemia, insulin resistance, blood lipids and satiety. METHOD: Studies on the short and long-term metabolic effects of diets with different glycemic indices will be presented and discussed. The review will focus primarily on clinical and epidemiological data, and will briefly discuss in vitro and animal studies related to possible mechanisms by which the glycemic index may influence chronic disease.     

Index glycémique,index insulinémique et régulation du poids corporel

It is commonly thought that diets eliciting low blood glucose and insulin responses result in increased satiety, reduced weight gain and/or increased weight loss. These effects have also been ascribed to foods with a low glycemic index (GI) and/or low insulinemic index (II). Evidence is accumulating that low GI foods may be more useful for weight loss than moderate reductions in carbohydrate intake, but the mechanisms for this are not clear. There are many different reasons why a food may have a low GI, such as the presence of fructose or dietary fiber, the nature of the starch, or the particle size; these factors may not influence body weight to the same extent. The results of studies suggesting that low GI foods increase short-term satiety and reduce short-term food intake are inconsistent and often confounded by factors other than differences in blood glucose response. Thus, it is not possible to ascribe the differences in satiety/food intake observed to differences in blood glucose per se. High blood insulin is commonly thought to cause an increase in body weight because it promotes fat storage rather than fat oxidation. However, there is evidence that adults with high blood insulin have lower food intake and gain less weight than those with normal blood insulin levels. Low GI starchy foods may help to regulate body weight because of a reduced rate of starch digestion leading to reduced energy absorption and increased colonic fermentation which, in turn, may have direct and indirect effects on the gut, pancreatic and adipose hormones which regulate energy intake and energy expenditure.     

Food intake and plasma ghrelin response during potato-, rice- and pasta-rich test meals

Objective Complex carbohydrates such as potato, rice and pasta are frequently consumed accompaniments of meat meals and have different effects on satiety, food intake, glucose, and insulin concentrations. The orexigenic gastric hormone ghrelin contributes to feeding regulation and as yet it is unknown whether there is any differential ghrelin response to these starchy food items corresponding to their effects on food intake. Methods In 11 subjects the effect of satiating amounts of potatoes, rice or pasta consumed together with 150g pork steak was examined on hunger/satiety ratings, food intake, plasma insulin, glucose and ghrelin concentrations. Results All meals led to comparable quantities of food intake while energy intake was significantly lower after potatoes. Satiety/hunger ratings were significantly different from basal for the entire 4 h period after rice and pasta meals, while they had returned to basal during the 4th hour after potatoes. After rice and pasta insulin rose significantly for 4 h. Ghrelin decreased during the 2nd and 3rd hour. In contrast potatoes stimulated insulin for the initial 2 h only while ghrelin rose significantly by 120 pg/ml over the 4 h period. A significant correlation was observed between ghrelin and hunger ratings while subsequent second meal food and energy intake did not differ irrespective of the preceding ghrelin concentration. Conclusion Compared to rice and pasta satiating amounts of potatoes coingested with meat result in lower energy intake and postprandial insulin concentrations, which is not counterbalanced during subsequent food intake despite higher ghrelin concentrations. The present data support the concept that ghrelin can affect hunger sensations but not necessarily food and energy intake.     

不同米饭对餐后血糖和饱腹感反应的影响

目的研究不同米饭样品的餐后血糖及饱腹感反应。方法 10名空腹健康志愿者食用含碳水化合物50 g的不同米饭样品:籼米饭(IR),黑籼米饭(BI),籼糯米饭(WL)和冷籼糯米饭(RW)。测餐后120 min血糖水平和血浆中胰岛素水平,同时记录180 min内的饱腹感及第二餐摄入的能量,计算血糖生成指数(GI)与胰岛素生成指数(II),以及在餐后1 h,2 h和3 h时各样品的饱腹感指数(SI)。结果无论WL还是RW食用后的GI均高于IR和BI。BI的II和SI最高。第二餐能量摄入最低。II分别与GI和SI具有一定的相关性,而GI和SI之间的相关性不大。结论籼糯米饭经过冷藏以后并不能降低血糖反应,两者均不适合糖尿病人作为主食BI适合需要控制体重和控制血糖者食用。结果提示,相比于GI,II与SI之间的联系可能更密切。     

How may refined carbohydrates affect satiety and mood?

Summary  Effects of refined carbohydrates on satiety and mood remain controversial. After a brief review of findings, some conceptual distinctions underlying mood and satiety are discussed; the physiological processes, cognitive processes and behaviours involved all need to be considered. From recent research on emotion and mood, a two-stage model is described of the psychological processes that mediate between carbohydrate ingestion, mood rating and food intake. This involves rapid non-conscious appraisal and slower cognitive appraisal. It is concluded that the effects of carbohydrates on subjective state and eating behaviour are fragile and liable to alter as a function of the prior state of an individual and the setting of ingestion.     

Redefining the glycemic index for dietary management of postprandial glycemia

The glycemic index (GI) is a component-referenced index, defined as the effect on blood glucose of glycemic carbohydrate in a food as a percentage of the effect of an equal amount of glucose. GI is not suitable for dietary management of postprandial glycemia because it refers to glycemic carbohydrate, not to food, it is static, i.e., unresponsive to intake, and it is relative in that it can be used appropriately only for equicarbohydrate comparisons. Food values for dietary management, in contrast, must be food-based, intake responsive and sensitive to variations in composition typical of diets. The limitations of GI could be overcome by expanding its definition beyond glycemic carbohydrate, to foods. GI could then be used as a food-referenced index, expressed as glycemic glucose equivalents (GGE)/100 g food, and extrapolated to GGE per common standard measure (CSM) as a value for the glycemic load exerted by familiar food quantities. GI(food) and GGE/CSM would then be expressed as are nutrients in food composition databases, would lie on the same quantity-dependent continuum and could be used with nutrient information to provide a more complete nutritional profile of a food than is provided by nutrients alone. GI would then be a practical adjunct to food composition data, which was its intended role.     

A diet containing food rich in soluble and insoluble fiber improves glycemic control and reduces hyperlipidemia among patients with type 2 diabetes mellitus

The clinical significance of fiber on metabolic control among people with type 2 diabetes is debatable. Patients with type 2 diabetes who consumed a diet containing food naturally rich in fiber (e.g., 50 g fiber/day, 50% soluble) for 6 weeks had significant improvements in glycemic control and lipid panels when compared with patients who consumed a diet with moderate amounts of fiber (e.g., 25 g fiber/day, 50% soluble). Whether this high intake of fiber-rich food, especially fruits, can be maintained, tolerated without side effects or micronutrient deficiencies, and affordable for longer than 6 weeks in people with type 2 diabetes remains to be determined.     

Dietary protein impact on glycemic control during weight loss

Diets with higher protein (1.5 g x kg(-1) x d(-1)) and reduced carbohydrates (120 to 200 g/d) appear to enhance weight loss due to a higher loss of body fat and reduced loss of lean body mass. While studies of prolonged use of moderate protein diets are not available, short-term studies report beneficial effects associated with increased satiety, increased thermogenesis, sparing of muscle protein loss, and enhanced glycemic control. Combined impacts of a moderate protein diet are likely derived from lower carbohydrates resulting in lower postprandial increase in blood glucose and lower insulin response, and higher protein providing increased BCAA leucine levels and gluconeogenic substrates. A key element in the diet appears to be the higher intake of BCAA leucine with unique regulatory actions on muscle protein synthesis, modulation of the insulin signal, and sparing of glucose use by stimulation of the glucose-alanine cycle. This review focuses on the contributions of leucine and the BCAA to regulation of muscle protein synthesis and glycemic control.     

Glycemic Index of Local Foods and Diets: The Mediterranean Experience

The Mediterranean diet is a healthful eating pattern associated with the prevention of coronary heart disease (CHD). Its main features are moderate intake of total fat (predominantly monounsaturated fat), low consumption of saturated fat and cholesterol-rich foods, and high intake of starch. Although this type of diet has beneficial effects on lipid metabolism, its high carbohydrate content might not be ideal for patients with diabetes or other conditions associated with insulin resistance (e.g., metabolic syndrome), who are known to be at particular risk of CHD. We therefore evaluated the glycemic response to starchy foods based on wheat (typical of the Italian diet) in patients with type 2 diabetes and identified certain characteristics of foods explaining their effects on postprandial glucose response. We found that spaghetti and potato dumplings, because of their low blood glucose response, represent a valid alternative to other starchy foods typical of the Mediterranean diet. Food structure plays an important role in determining the accessibility of starch to digestion, thus influencing the postprandial blood glucose response, which modulates plasma insulin and lipid levels.     

Repeated consumption of a large volume of liquid and semi-solid foods increases ad libitum intake, but does not change expected satiety

Food intake and a food's expected satiating effect initially rely on sensory attributes. People will learn about the food's satiating capacity by exposure. We investigated whether repeated consumption changed the expected satiety effects and intake of iso-energetic liquid and semi-solid foods. In a randomised cross-over study, participants (n=53; age: 21±2.9y; BMI: 21.8±2.0kg/m(2)) consumed one of two iso-energetic dairy foods (liquid or semi-solid) for breakfast in each 5-day test condition. Expectations regarding satiety were measured on days 1, 2, and 5. Foods were offered ad libitum on days 1 and 5 and in a fixed volume on days 2-4. Appetite sensations were rated up to 180min after the start of the session on fixed time points. Expected satiety effects of the semi-solid food were higher than of the liquid food on all days (p<0.0001). Ad libitum intake of the liquid food was higher than of the semi-solid food on day 1 (liquid: 391±177g, semi-solid: 277±98g; p<0.0001) and day 5 (liquid: 477±161g, semi-solid: 375±148g; p<0.0001). On day 2, hunger was rated lower and fullness rated higher after the semi-solid compared with the liquid food; on day 4, no differences were observed (significant product(?) exposure interaction AUC). Changes in hunger and fullness indicated that the fixed volumes of liquid and solid food were perceived to be equally satiating after repeated consumption, but this did not result in the anticipated changes: expected satiety effects remained lower, and ad libitum intake higher for the liquid compared with the semi-solid food. The effect of texture on a food's expected satiety effects and its ad libitum intake appears to be large, also after repeated consumption. Expectations based on sensory cues are not easily changed.     

The effects of equal-energy portions of different breads on blood glucose levels, feelings of fullness and subsequent food intake

OBJECTIVE: This study compared the effects of equal-energy portions of 7 different breads on feelings on fullness and subsequent ad libitum food intake. A satiety index score (SI) was calculated for each of the breads. DESIGN: Within-subject, repeated-measures design. SUBJECTS AND INTERVENTION: Ten healthy subjects participated in the study. Subjects fasted for > or =10 hours overnight and then reported to the research center the next morning, where they first completed baseline satiety ratings, gave a fasting blood sample, and then consumed a test bread. Additional finger prick blood samples and satiety ratings were collected at 15-minute intervals over 120 minutes, after which the subjects' ad libitum intake of food was recorded. A satiety index (SI) score was calculated for each test food by dividing the area under the 120-m satiety response curve (AUC) for the test bread by the satiety AUC for the reference bread (regular white bread) and multiplying by 100%. RESULTS: The mean SI scores for the breads ranged from 100% to 561%, with regular white bread having the lowest SI score. Mean SI scores were negatively correlated with energy intake at a test meal after 120 m (r=-0.88, P<.01, n=7) and total day energy intakes (r=-0.72, P<.05, n=7). The strongest predictor of the breads' SI scores was their portion size and thus energy density. The breads' glycemic responses were not significantly associated with fullness responses. APPLICATIONS: Ingredients and food processing methods are available for the production of palatable, high-satiety versions of processed foods, which may be useful for weight control diets. SI scores would be a useful addition to food labels to indicate which foods are less likely to be overeaten and could be used by dietitians to develop weight control plans to help reduce energy intakes without increased hunger.     

Use of viscous fibres in beverages for appetite control: a review of studies

Abstract

Dietary fibres, particularly viscous fibres appear to be more effective for appetite control (reduce subjective appetite, energy intake and/or body weight). Three types of viscous fibres, pectin, alginate and cereal beta-glucan, were identified as potential satiety-enhancing ingredients. The aim of this review was to collect evidence from human intervention studies evaluating pectins, alginates and beta-glucans in beverages, liquid preloads and liquid test meals for their satiety effects. Our focused, narrative review of several satiety studies shows an overall consistent result on the effectiveness of pectin, alginate and beta-glucan for appetite control. Beverages or liquid test meals are probably the better delivery mode for these fibres, as their effect on satiety is affected by their physico–chemical properties. Most, if not all, of these reviewed studies gave little or no consideration to the potential effects of common food processing (e.g. pasteurisation, ultra-high temperature process) on the physico–chemical properties of these fibre-containing beverages. This is one of the research gaps we have identified warranting further work, which is likely to be of significance from the industry and consumer perspective.     

Gastrointestinal Nutrient Infusion Site and Eating Behavior: Evidence for A Proximal to Distal Gradient within the Small Intestine?

The rapidly increasing prevalence of overweight and obesity demands new strategies focusing on prevention and treatment of this significant health care problem. In the search for new and effective therapeutic modalities for overweight subjects, the gastrointestinal (GI) tract is increasingly considered as an attractive target for medical and food-based strategies. The entry of nutrients into the small intestine activates so-called intestinal “brakes”, negative feedback mechanisms that influence not only functions of more proximal parts of the GI tract but also satiety and food intake. Recent evidence suggests that all three macronutrients (protein, fat, and carbohydrates) are able to activate the intestinal brake, although to a different extent and by different mechanisms of action. This review provides a detailed overview of the current evidence for intestinal brake activation of the three macronutrients and their effects on GI function, satiety, and food intake. In addition, these effects appear to depend on region and length of infusion in the small intestine. A recommendation for a therapeutic approach is provided, based on the observed differences between intestinal brake activation.     

Macronutrients and mental performance

There is currently intense interest in the effects of macronutrients on psychological states, mental performance, and well-being. A strong theoretical perspective has guided work on carbohydrates and their relation to brain serotoninergic function with concomitant effects on performance. The clearest and most reliable effects have been observed for the beneficial action of glucose on cognitive performance, supported by investigations of hypoglycemia, which is associated with general impairment of cognitive performance. The effects of complex carbohydrates are less distinct and change with time of day; e.g., carbohydrate at breakfast tends to improve morning performance. However, these studies are rarely decisive. Far fewer experiments have been performed on protein and fat, and it is difficult to draw any firm conclusions. Macronutrients are seldom given alone, proportions of protein and fat differ greatly between studies, and comparisons are frequently performed with no food at all. Food intake may mitigate the effects of low doses but not of high doses of alcohol on performance. Effects of macronutrients on cognitive performance may be dependent on their effects on glucose metabolism, metabolic activation, or serotonin. Other factors that modify effects include time of day, circadian rhythms, type of task, habitual diet, and vulnerability of the population.     

Effects of short-chain fructooligosaccharides on satiety responses in healthy men and women

In view of a dramatic increase in the incidence of obesity, the present study examined the appetite effects of a functional fiber as a potential dietary intervention. Fiber may increase satiety. Satiety effects also may be linked to colonic fermentation. Short-chain fructooligosaccharide (scFOS) are fermentable fibers that can be added to foods to influence these actions. The primary objective of this study was to determine if scFOS affects satiety and hunger and has an additive effect on food intake. Using a double-blind crossover design, 20 healthy subjects were assigned to consume two separate doses of 0 g, 5 g, or 8 g of scFOS. The first dose was mixed into a hot cocoa beverage and served with a breakfast meal of a bagel and cream cheese. A beverage was used in the test meal due to the ease with which scFOS can be added to this medium. Satiety was assessed with visual analogue scales (VASs) at 0, 15, 30, 45, 60, 90, 120, 180, and 240 min. Ad libitum food intake was measured at a lunch meal provided at the test site at 240 min. Subjects then recorded their food intake over the remainder of the 24-h study day. The second dose of scFOS was consumed in the form of 3 solid, chocolate-flavored chews (51-67 total kcal) without additional food or drink, 2h prior to the subject's dinner meal. Breath hydrogen measures were collected prior to the breakfast test meal (0 min) and the ad libitum lunch (240 min). Gastrointestinal tolerance was evaluated over the course of the 24-h study day using VAS. All treatments were well tolerated. No differences in subjective satiety over the morning, or food intake at lunch, were found. Over the remainder of the day, the high dose of scFOS reduced food intake in women, but increased food intake in men, suggesting a gender difference in the longer-term response. Breath hydrogen, used as a marker of fermentation, increased in a dose-dependent manner. These results indicate that scFOS undergoes fermentation within 240 min; however, acceptable amounts of scFOS did not enhance acute satiety or hunger.     

Influence of dietary carbohydrates and glycaemic response on subjective appetite and food intake in healthy elderly persons

Increased satiety and decreased food intake are reported following the consumption of low glycaemic index (GI) foods, which gradually increase blood glucose. This observation, however, is not uniformly supported and few studies have examined the impact of different GI foods on satiety and intake in the elderly. After an overnight fast, 10 men and 10 women (aged 60-82 years) consumed similar amounts of available carbohydrate as high (glucose drink or potatoes) or low (barley) GI foods or a non-energy placebo drink on four mornings. Blood glucose and subjective appetite were measured throughout a 120 min post-ingestion period, followed by consumption of an ad libitum lunch. Differences in plasma glucose after test food ingestion (glucose > potatoes > barley > placebo; P < 0.03) did not predict subjective appetite or lunch intake. Potatoes increased subjective satiety the most, followed by barley, then glucose, which trended towards greater satiety than placebo. Potatoes led to less hunger than placebo (P = 0.0023) and less prospective consumption than the other three foods (P < 0.0083), and potatoes and barley led to greater fullness than glucose and placebo (P < 0.0001). Lunch intake was decreased, compared with placebo (502 +/- 47 kcal, P < 0.031), by potatoes (405 +/- 40 kcal) and barley (441 +/- 41 kcal); however, only potatoes (41.9 +/- 12.3%) led to greater compensation at lunch for test food ingestion compared with glucose (11.9 +/- 9.5%, P = 0.016). These results suggest that elderly subjects are sensitive to the effects of different foods on subjective appetite and food intake, and that the GI of the foods tested did not predict their effects on satiety and food intake.     

Dietary carbohydrates, fiber, and breast cancer risk

Dietary fiber, fiber fractions, carbohydrate, glycemic index, and glycemic load were prospectively assessed five times over 18 years with a validated food frequency questionnaire in relation to breast cancer risk among 88,678 women (aged 34-59 years at baseline) in the Nurses' Health Study. Incident breast cancer occurred in 4,092 of these women between 1980 and 1998. The authors observed no material association between carbohydrate intake, glycemic index and glycemic load, total dietary fiber intake, and breast cancer risk. The relative risks for the highest versus the lowest quintile of intake were 0.97 (95% confidence interval (CI): 0.87, 1.08) for carbohydrates, 1.08 (95% CI: 0.97, 1.19) for glycemic index, 0.99 (95% CI: 0.89, 1.10) for glycemic load, and 0.98 (95% CI: 0.87, 1.11) for fiber. The relative risk comparing those in the highest 0.7% of fiber intake (>30 g/day) with those in the lowest 10% of fiber intake (< or =10 g/day) was 0.68 (95% CI: 0.43, 1.06). Analyses stratified by menopausal status and body mass index also showed no clear risk pattern. In this cohort of middle-aged women, no overall association was found for dietary carbohydrates, glycemic index and glycemic load, and breast cancer risk. This study also confirmed the lack of an overall association between intake of fiber and fiber types and breast cancer risk observed in other prospective studies.