High-glycemic index foods, hunger, and obesity: is there a connection?

Effect of Galactose Ingestion Before and During Exercise on Substrate Oxidation, Postexercise Satiety, and Subsequent Energy Intake in Females

OBJECTIVE

To examine the effects of consuming a galactose carbohydrate (CHO) drink on substrate oxidation, postexercise satiety, and subsequent energy intake.

METHODS

Nine recreationally active eumenorrheic females undertook 3 trials, each consisting of running for 60 minutes at 65% VO(2peak) followed immediately by a 90-minute rest period. Prior to (300 ml) and at 15-minute intervals during exercise (150 ml), participants consumed either a glucose (GLU: GI 89) or galactose (GAL: GI 20) drink, each of which contained 45 g of CHO, or an artificially sweetened placebo (PLA). Following the rest period, participants were provided with an ad libitum test lunch and asked to record food intake for the remainder of the day.

RESULTS

Plasma glucose was significantly greater throughout exercise and rest following the GLU trial compared with the GAL and PLA trials (P < 0.05); however there were no differences in CHO oxidation. Hunger was significantly lower (P < 0.05) throughout the GAL compared to the GLU and PLA trials. There were no significant differences between trials for energy intake during the postexercise meal. Overall net energy balance for the 24 hours was negative in both the GAL (-162 ± 115 kcal; P < 0.05 vs GLU) and PLA trials (-49 ± 160 kcal).

CONCLUSIONS

Results demonstrate that ingesting a solution containing GAL before and during exercise can positively impact postexercise satiety and energy balance throughout the day, compared to a more readily available and widely consumed form of CHO. Despite this, there appears to be no apparent benefit in consuming a CHO beverage on fuel utilization for this moderate exercise intensity and duration.

Greater healthful food variety as measured by the US Healthy Food Diversity index is associated with lower odds of metabolic syndrome and its components in US adults

BACKGROUND

Consuming a wider variety of nutrient-dense foods may promote adherence to healthful dietary patterns, leading to improved dietary quality and enhanced metabolic health.

OBJECTIVE

We used the US Healthy Food Diversity (HFD) index to simultaneously measure dietary variety, quality, and proportionality, hypothesizing a priori that race/ethnicity may moderate associations between diet and health.

METHODS

A representative sample of adults (n = 7470) aged 20+ y with two 24-h recalls and complete outcome data from the cross-sectional NHANES 2003-2006 were selected. US HFD values were generated using a previously validated equation with a theoretical range from 0 to nearly 1, with higher scores indicative of more varied diets with a higher proportion of healthful food groups. Metabolic syndrome (MetS) was defined using the most recent harmonized definition. Survey-weighted multivariable linear and logistic regression, adjusted for demographic factors, smoking, energy, screen time, and leisure activity, were used to compute means and ORs (95% CIs).

RESULTS

Adults in the third vs. first US HFD tertile had 21% lower odds of MetS [OR (95% CI): 0.79 (0.64, 0.98)] as well as lower odds of hypertension [0.83 (0.70, 0.995] and elevated waist circumference [0.75 (0.66, 0.86] after multivariable adjustment (P-trend < 0.05). The age- and sex-adjusted odds of low serum HDL cholesterol and impaired fasting plasma glucose (P-trend < 0.05) were lower in the highest vs. lowest US HFD tertile but attenuated with multivariable adjustment (P = 0.06 and 0.22, respectively). Notably, the US HFD index was only protective against adiposity among non-Hispanic white (NHW) and non-Hispanic black (NHB) adults, and MetS associations were driven by NHW adults. No associations were observed among Hispanic adults for any MetS components.

CONCLUSIONS

Greater healthful food variety was associated with lower odds of MetS and some MetS components in the total population, NHW adults, and NHB adults. This study provides preliminary evidence that healthful food diversity may protect against MetS and highlights the need for longitudinal and experimental research.

A blended- rather than whole-lentil meal with or without α-galactosidase mildly increases healthy adults' appetite but not their glycemic response

BACKGROUND

Disrupting the physical structure of pulses by blending them or by using a digestive supplement (α-galactosidase) to reduce intestinal discomfort could potentially negate the previously observed beneficial effects of whole pulses of lowering appetitive and glycemic responses because of more rapid digestion.

OBJECTIVE

We hypothesized that blended lentils, α-galactosidase, or both increase postprandial appetite and blood glucose responses vs. whole lentils.

METHODS

Men and women [n = 12; means ± SDs body mass index (kg/m(2)): 23.3 ± 3.1; aged 28 ± 10 y] consumed breakfast meals containing whole (W), blended (B), or no lentils [control (C)], each with 3 α-galactosidase or placebo capsules in a randomized, crossover, double-blind placebo-controlled trial. Between each test day there was a 3- to 5-d washout period.

RESULTS

Mixed-model ANOVA showed effects of meal on postprandial appetite and glucose (P = 0.0001-0.031). The B meal resulted in higher postprandial appetite ratings than did the W meal but not the C meal for hunger, desire to eat, and prospective consumption (Δ = 0.4-0.5 points; P = 0.002-0.044). Postprandial glucose concentration was 4.5 mg/dL lower for the B meal than for the C meal (P < 0.0001) but did not differ from the W meal. There were no main effects of α-galactosidase, but there were meal × α-galactosidase interaction effects, with a greater postprandial desire to eat and lower postprandial fullness with the B meal than with the 2 other meals in the placebo condition but not in the α-galactosidase condition.

CONCLUSIONS

Blending lentils increased appetite (∼6%), but not glycemic response, compared with whole lentils, whereas α-galactosidase did not. Both B and W meals may be consumed (with or without an α-galactosidase supplement) with little impact on appetite, without increasing glycemic response. This trial was registered at clinicaltrials.gov as NCT02110511.

Glycemic response of a carbohydrate-protein bar with ewe-goat whey

In this study we examined the glycaemic index (GI) and glycaemic load (GL) of a functional food product, which contains ewe-goat whey protein and carbohydrates in a 1:1 ratio. Nine healthy volunteers, (age, 23.3 ± 3.9 years; body mass index, 24.2 ± 4.1 kg·m2; body fat %, 18.6 ± 10.0) randomly consumed either a reference food or amount of the test food both with equal carbohydrate content in two visits. In each visit, seven blood samples were collected; the first sample after an overnight fast and the remaining six at 15, 30, 45, 60, 90 and 120 min after the beginning of food consumption. Plasma glucose concentration was measured and the GI was determined by calculation of the incremental area under the curve. The GL was calculated using the equation: test food GI/100 g available carbohydrates per test food serving. The GI of the test food was found to be 5.18 ± 3.27, while the GL of one test food serving was 1.09 ± 0.68. These results indicate that the tested product can be classified as a low GI (<55) and low GL (<10) food. Given the health benefits of low glycaemic response foods and whey protein consumption, the tested food could potentially promote health beyond basic nutrition.

Effects of different protein and glycemic index diets on metabolic profiles and substrate partitioning in lean healthy males

Dietary glycemic index (GI) and protein affects postprandial insulin responses and consequently 24 h glucose metabolism and therefore substrate partitioning. This study investigated the mechanistic effects of different protein and GI diets on 24 h profiles of metabolic markers and substrate partitioning. After 3 days of diet and physical activity standardization, 10 healthy male subjects (BMI: 22.5 ± 0.6 kg/m2) stayed in a respiration chamber 4 times for 36 h each time to measure substrate partitioning. All subjects randomly received four isoenergetic diets: a normal (15En%) dairy protein and low GI (<40 units) (NDP-LGI) diet; a high (25En%) dairy protein and low GI (HDP-LGI) diet; a normal vegetable protein and low GI (NVP-LGI) diet; or a normal dairy protein and high GI (>60 units) (NDP-HGI) diet. During the day, blood was sampled at fixed time points for the measurement of metabolic markers and satiety hormones. The HDP-LGI diet increased 24 h protein oxidation and sleeping metabolic rate (SMR) compared with the NDP-LGI diet (p < 0.002). No significant differences in 24 h carbohydrate and fat oxidation (day and night) were found between all intervention diets. Net incremental area under the curve (net iAUC) of 24 h plasma glucose decreased in the HDP-LGI diet compared with the NDP-LGI diet (p < 0.01), but no effect was observed on insulin levels. No difference in appetite profiles were observed between all intervention diets. The lower 24 h glycemic profile as a result of a high dairy protein diet did not lead to changes in 24 h substrate partitioning in lean healthy subjects with a normal insulin sensitivity.

Dietary intake following experimentally restricted sleep in adolescents

STUDY OBJECTIVE

To examine the relationship between sleep and dietary intake in adolescents using an experimental sleep restriction protocol.

DESIGN

Randomized crossover sleep restriction-extension paradigm.

SETTING

Sleep obtained and monitored at home, diet measured during an office visit.

PARTICIPANTS

Forty-one typically developing adolescents age 14-16 years.

INTERVENTIONS

The 3-week protocol consisting of a baseline week designed to stabilize the circadian rhythm, followed randomly by 5 consecutive nights of sleep restriction (6.5 hours in bed Monday-Friday) versus healthy sleep duration (10 hours in bed), a 2-night washout period, and a 5-night crossover period.

MEASUREMENTS

Sleep was monitored via actigraphy and teens completed validated 24-hour diet recall interviews following each experimental condition.

RESULTS

Paired-sample t-tests examined differences between conditions for consumption of key macronutrients and choices from dietary categories. Compared with the healthy sleep condition, sleep-restricted adolescents' diets were characterized by higher glycemic index and glycemic load and a trend toward more calories and carbohydrates, with no differences in fat or protein consumption. Exploratory analyses revealed the consumption of significantly more desserts and sweets during sleep restriction than healthy sleep.

CONCLUSIONS

Chronic sleep restriction during adolescence appears to cause increased consumption of foods with a high glycemic index, particularly desserts/sweets. The chronic sleep restriction common in adolescence may cause changes in dietary behaviors that increase risk of obesity and associated morbidity.

Short-term impact of sugar consumption on hunger and ad libitum food intake in young women

The hypothesis of this study was that greater sugar consumption at breakfast promotes a stronger sensation of hunger and a later increase in energy consumption. The objective was to assess the relation between sugar consumption in a meal and the subsequent sensations of hunger and ad libitum food consumption. Sixteen women consumed a breakfast accompanied by 2 drinks sweetened ad libitum with sugar. After 3 h, a lunch was offered to evaluate ad libitum food consumption. During the period from breakfast to lunch, hunger sensations were evaluated at 30 min intervals. Women were divided according to the median amount of sugar used to sweeten the breakfast drinks (20 g). The group who consumed sugar above the median showed a greater hunger sensation in the preprandial period, and a greater ad libitum intake at lunch (390 ± 130 g × 256 ± 67 g, P = 0.002), compared to the group who had a lower sugar consumption. The amount of sugar consumed at breakfast was correlated positively with the sensation of preprandial hunger and food intake at lunch. We concluded that foods with a high glycemic index can modulate the appetite within a short period of time.

Improvement of the metabolic syndrome profile by soluble fibre - guar gum - in patients with type 2 diabetes: a randomised clinical trial

A diet rich in fibre seems to protect against the metabolic syndrome (MetS), but there is scarce information about the role of fibre intake in patients with the MetS and diabetes. The aim of the present study was to evaluate the effects of soluble fibre from partially hydrolysed guar gum (PHGG) on the MetS and cardiovascular risk factors in patients with type 2 diabetes. In the present randomised controlled clinical trial, forty-four patients with type 2 diabetes (males 38·6 %, age 62 (SD 9) years, diabetes duration 14·2 (SD 9·6) years) and the MetS underwent clinical, laboratory and dietary evaluations at baseline, 4 and 6 weeks. All patients followed their usual diet and the intervention group (n 23) received an additional 10 g/d of PHGG. In the intervention group, waist circumference (WC), glycated Hb (HbA1c), 24 h urinary albumin excretion (UAE) and serum trans-fatty acids (FA) were reduced in comparison with baseline after 4 and 6 weeks: WC 103·5 (SD 9·5) to 102·1 (SD 10) to 102·3 (SD 9·7) cm; HbA1c 6·88 (SD 0·99) to 6·64 (SD 0·94) to 6·57 (SD 0·84) %; 24 h UAE 6·8 (interquartile range 3·0-17·5) to 4·5 (interquartile range 3·0-10·5) to 6·2 (interquartile range 3·0-9·5) mg; trans-FA 71 (interquartile range 46-137) to 67 (interquartile range 48-98) to 57 (interquartile range 30-110) mg/l (P< 0·05 for all). The only change in the control group was weight reduction: 77·0 (SD 13·5) to 76·2 (SD 13·3) to 76·1 (SD 13·4) kg (P= 0·005). Other MetS components (blood pressure, TAG, HDL-cholesterol, fasting plasma glucose), total and LDL-cholesterol, C-reactive protein and endothelin-1 did not change in either group. In patients with type 2 diabetes and the MetS, the addition of PHGG to the usual diet improved cardiovascular and metabolic profiles by reducing WC, HbA1c, UAE and trans-FA.

Food-based ingredients to modulate blood glucose

Maintenance of normal blood glucose levels is important for avoiding chronic diseases such as type 2 diabetes, cardiovascular problems, and obesity. Type 2 diabetes is one of the major health problems affecting the world population and this condition can be exacerbated by poor diet, low physical activity, and genetic abnormalities. Food plays an important role in the management of blood glucose and associated complications in diabetes. This is attributed to the ability of food-based ingredients to modulate blood glucose without causing any adverse health consequences. This chapter focuses on four important food groups such as cereals, legumes, fruits, and spices that have active ingredients such as soluble dietary fiber, polyphenols, and antinutrients with the ability to reduce glycemic and insulin response in humans. Other food ingredients such as simple sugars, sugar alcohols, and some proteins are also discussed in moderation.

(1)H NMR spectroscopy for the in vitro understanding of the glycaemic index

The glycaemic index (GI) characterises foods by using the incremental area under the glycaemic response curve relative to the same amount of oral glucose. Its ability to differentiate between curves of different shapes, the peak response and other aspects of the glycaemic response is contentious. The present pilot study aimed to explore the possibility of using 1H NMR spectroscopy to better understand in vivo digestion characteristics as reflected in the glycaemic response of carbohydrate-rich foods; such an approach might be an adjunct to the in vivo GI test. The glycaemic response of two types of raw wheat flour (2005 from Griffith NSW, Chara, Row 10, Plot 6:181 and store-bought Colese Plain Flour) and a cooked store-bought flour was tested and compared with results recorded during the in vitro enzymatic digestion of the wheat flour samples by glucoamylase from Aspergillus niger (EC 3.2.1.3) as monitored by 1H NMR spectroscopy. Comparing the digestion time courses of raw and cooked wheat starch recorded in vitro strongly suggests that the initial rate of glucose release in vitro correlates with the glycaemic spike in vivo. During the in vitro time courses, approximately four times as much glucose was released from cooked starch samples than from raw starch samples in 90 min. Monitoring enzymatic digestion of heterogeneous mixtures (food) by 1H NMR spectroscopy showcases the effectiveness of the technique in measuring glucose release and its potential use as the basis of an in vitro method for a better understanding of the GI.

The zone diet: an anti-inflammatory, low glycemic-load diet

The Zone Diet was developed on the concept that the hormonal responses of macronutrients could be orchestrated to maintain key hormones within therapeutic zones to control inflammatory responses. In particular, the two hormonal systems that are directly affected by dietary macronutrients are (1) the insulin/glucagon axis and (2) eicosanoids. Each of these hormonal systems can have a significant impact on the inflammatory process. This hormonal approach to optimizing an anti-inflammatory diet has significant ramifications in treatment of those chronic diseases (obesity, type 2 diabetes, and cardiovascular disease) that are known to produce inflammatory responses. On the other hand, an inappropriate balance of macronutrients (especially high glycemic- load carbohydrates) can lead to increased inflammation. A primary example of this is the promotion of the United States Department of Agriculture's Food Guide Pyramid. Since its adoption, the prevalence of obesity and type 2 diabetes has risen substantially. Both conditions also demonstrate a significant increase in inflammatory markers. The purpose of this article is to review the historical factors that led to the development of the Zone Diet, to understand how the Zone Diet can alter inflammatory responses, and to review the published literature on its ability to affect hormonal and metabolic responses.

Impact of postprandial glycaemia on health and prevention of disease

Postprandial glucose, together with related hyperinsulinemia and lipidaemia, has been implicated in the development of chronic metabolic diseases like obesity, type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). In this review, available evidence is discussed on postprandial glucose in relation to body weight control, the development of oxidative stress, T2DM, and CVD and in maintaining optimal exercise and cognitive performance. There is mechanistic evidence linking postprandial glycaemia or glycaemic variability to the development of these conditions or in the impairment in cognitive and exercise performance. Nevertheless, postprandial glycaemia is interrelated with many other (risk) factors as well as to fasting glucose. In many studies, meal-related glycaemic response is not sufficiently characterized, or the methodology with respect to the description of food or meal composition, or the duration of the measurement of postprandial glycaemia is limited. It is evident that more randomized controlled dietary intervention trials using effective low vs. high glucose response diets are necessary in order to draw more definite conclusions on the role of postprandial glycaemia in relation to health and disease. Also of importance is the evaluation of the potential role of the time course of postprandial glycaemia.

Reducing the glycemic index or carbohydrate content of mixed meals reduces postprandial glycemia and insulinemia over the entire day but does not affect satiety

OBJECTIVE

We evaluated the effects of mixed meals differing in glycemic index (GI) and carbohydrate content on postprandial serum glucose and insulin response, hunger, and satiety over the course of a 12-h day.

RESEARCH DESIGN AND METHODS

In this randomized crossover trial, 26 overweight or obese adults received four diets in random order (high GI, high carbohydrate [HGI-HC]; high GI, low carbohydrate [HGI-LC]; low GI, high carbohydrate [LGI-HC]; and low GI, low carbohydrate [LGI-LC]). All meals were prepared by a metabolic kitchen. Participants received breakfast, lunch, and dinner over the course of a 12-h day. Primary outcomes were postprandial serum glucose and insulin quantified as area under the curve. Hunger, fullness, and satiety were assessed by visual analog scale.

RESULTS

The HGI-LC, LGI-HC, and LGI-LC diets significantly reduced glucose and insulin area under the curve compared with the HGI-HC diet (P < 0.001 for all comparisons). There were no significant differences in ratings of hunger, fullness, or satiety between the different dietary treatments.

CONCLUSIONS

Reducing the GI or carbohydrate content of mixed meals reduces postprandial glycemia and insulinemia, and these changes can be sustained over the course of an entire day. However, there were no differences in subjective hunger and satiety ratings between the diets. These results demonstrate that maintaining a low GI or glycemic load diet is an effective method of controlling serum glucose and insulin levels.

Glycaemic, insulin and ghrelin responses to traditional South Asian flatbreads in diabetic and healthy subjects

In the South-East Asian subcontinent, flatbreads contribute the main portion of carbohydrate to a meal. There are no specific data on the effect of different flatbreads on satiety and recurrent hunger, as indicated by the duration of ghrelin suppression after a meal. The present study was designed to examine the glycaemic, insulin and ghrelin responses to traditional subcontinental breads in type 2 diabetic subjects and healthy volunteers. For this purpose, twelve normoglycaemic healthy volunteers and ten type 2 diabetic patients, in the fasting state, consumed one of five common flatbreads on consecutive days. Capillary blood glucose was examined in the fasting state and serially for 5 h after a meal. Serum insulin and ghrelin levels were determined at hourly intervals for 5 h after the consumption of bran and plain chapatti flatbreads. The incremental area under the curve (iAUC) was calculated for glycaemic and insulin responses, while the net AUC was used to assess the ghrelin response. The results showed that glycaemic and insulin iAUC were lowest for bran chapatti, and highest for plain chapatti. Furthermore, bran chapatti showed maximum ghrelin suppression in both normal and diabetic groups. In conclusion, the low-glycaemic index bran chapatti flatbread had a lower postprandial glycaemic excursion and insulin response, and a more prolonged suppression of ghrelin levels, compared with the plain chapatti flatbread, and in each case, the difference was greater for the diabetic subjects than for the normal subjects. The inclusion of these flatbreads in the diabetic/weight-reducing diet may help weight loss by promoting satiety and reducing hyperinsulinaemia.

Fiber, protein, and lupin-enriched foods: role for improving cardiovascular health

Cardiovascular diseases (CVD) are the leading cause of death globally (World Health Organisation, 2011). Many of the risk factors for CVD are modifiable, including overweight and obesity. Numerous strategies have been proposed to fight CVD, with a special focus being placed on dietary interventions for weight management. The literature suggests that two nutrients, fiber and protein, may play significant roles in weight control and hence cardiovascular health. Increasing both protein and fiber in the diet can be difficult because popular low-carbohydrate and high-protein diets tend to have considerably low-fiber intakes (Slavin, 2005). One approach to obtain both is to develop functional foods using unique ingredients. Lupin flour is a novel food ingredient derived from the endosperm of lupin. It contains 40-45% protein, 25-30% fiber, and negligible sugar and starch (Petterson and Crosbie, 1990). Research conducted to date reveals that lupin-enriched foods, which are naturally high in protein and fiber, may have a significant effect on CVD risk factors. This review explores whether there is a role for fiber-, protein-, and lupin-enriched foods in improving cardiovascular health.

The individual and combined effects of glycemic index and protein on glycemic response, hunger, and energy intake

Although high protein and low glycemic index (GI) foods are thought to promote satiety, little is known about the effects of GI, protein, and their interaction on hunger and energy intake several hours following a mixed meal. This study investigated the long term effects of GI, protein, and their combined effects on glucose, insulin, hunger, and energy intake in healthy, sedentary, overweight, and obese adults (BMI of 30.9 ± 3.7 kg/m(2)). Sixteen individuals participated separately in four testing sessions after an overnight fast. The majority (75%) were non-Hispanic Blacks. Each consumed one of four breakfast meals (high GI/low protein, high GI/high protein, low GI/low protein, low GI/high protein) in random order. Visual analog scales (VAS) and blood samples were taken at baseline, 15 min, and at 30 min intervals over 4 h following the meal. After 4 h, participants were given the opportunity to consume food ad libitum from a buffet style lunch. Meals containing low GI foods produced a smaller glucose (P < 0.002) and insulin (P = 0.0001) response than meals containing high GI foods. No main effects for protein or interactions between GI and protein were observed in glucose or insulin responses, respectively. The four meals had no differential effect on observed energy intake or self-reported hunger, satiety, and prospective energy intake. Low GI meals produced the smallest postprandial increases in glucose and insulin. There were no effects for GI, protein, or their interaction on appetite or energy intake 4 h after breakfast.

Dietary approaches to the treatment of obesity

Various dietary strategies can effectively reduce weight, as shown by this review. Those that are coupled with behavior therapy and ongoing support tend to produce longer lasting effects. Improvements in health parameters are observed with each dietary strategy. Improvements in diabetes and CVD risk factors have been observed with diets ranging from 10% fat to 45% fat. HP diets seem to be particularly effective in reducing fat mass and TAG, especially in individuals with dyslipidemia and who are at risk for type 2 diabetes. Likewise, LC diets have been shown to be effective in decreasing TAG and VLDL and increasing HDL. Although low-GI diets do not seem to be superior to any other diet for weight loss, there is evidence to suggest that they may provide some metabolic benefit for those with type 2 diabetes. Clearly, all of these diets have benefits but they can be realized only when they are followed. A common theme across studies is poor long-term adherence and weight regain. Dansinger and colleagues found a strong association between diet adherence and clinically significant weight loss, suggesting that “sustained adherence to a diet” rather than “following a certain type of diet” is the key to successful weight management.

The acute effects of a pulse-containing meal on glycaemic responses and measures of satiety and satiation within and at a later meal

Pulses are low glycaemic foods; however, their effect on satiation is unknown. The objective was to determine the effects of an ad libitum pulse meal on food intake (FI), appetite and blood glucose (BG) before and after a test meal (4 h later) and on FI at the test meal. Males (n 24, 22·8 kg/m2) received one of four treatments or control. The pulse treatments contained pasta and tomato sauce and 44 % of energy from: (1) chickpeas, (2) lentils, (3) navy beans or (4) yellow peas. The control was pasta and tomato sauce (pasta and sauce). FI (satiation) was measured at the treatment meal (0-20 min) and at an ad libitum pizza meal 4 h later. BG and appetite were measured from 0 to 340 min. At the treatment meal, lentils led to lower FI compared to chickpeas and pasta and sauce, whereas navy beans led to lower FI compared to chickpeas. Also, lentils led to lower cumulative FI compared to pasta and sauce. All pulses led to lower BG peak and cumulative area under the curve (AUC; 0-340 min); however, only chickpeas, lentils and navy beans reduced pre-pizza meal BG AUC (0-260 min) relative to pasta and sauce. Chickpeas led to lower post-pizza meal BG AUC (260-340 min) compared to navy beans and yellow peas. Consumption of pulses in a high-glycaemic meal contributes to earlier satiation, lower BG following the meal and after a later meal, but these effects are specific to pulse type and cannot be explained by their glycaemic properties alone.

First and second meal effects of pulses on blood glucose, appetite, and food intake at a later meal

Pulses are low-glycemic appetite-suppressing foods, but it is not known whether these properties persist after being consumed as part of a meal and after a second meal. The objective of this study was to determine the effects of a fixed-size pulse meal on appetite and blood glucose (BG) before and after an ad libitum test meal (pizza) and on food intake (FI) at the test meal. Males (n = 25; 21.3 ± 0.5 years; 21.6 ± 0.3 kg·m(-2)) randomly consumed 4 isocaloric meals: chickpea; lentil; yellow split pea; and macaroni and cheese (control). Commercially available canned pulses provided 250 kcal, and were consumed with macaroni and tomato sauce. FI was measured at a pizza meal 260 min after consumption of the isocaloric meal. BG and appetite were measured from 0 to 340 min. The lentil and yellow pea, but not chickpea, treatments led to lower appetite ratings during the 260 min prepizza meal period, and less FI at the pizza meal, compared with macaroni and cheese (p < 0.05). All pulse treatments lowered BG immediately following consumption (at 20 min) (p < 0.05), but there was no effect of treatment on prepizza meal BG AUC (p = 0.07). Immediately after the pizza meal, BG was lower following the chickpea and lentil treatments, but not the yellow pea treatment (p < 0.05). Postpizza meal BG AUC was lower following the chickpea and lentil treatments than in the yellow pea treatment (p < 0.05). The beneficial effects of consuming a pulse meal on appetite, FI at a later meal, and the BG response to a later meal are dependent on pulse type.

Effects of different protein content and glycaemic index of ad libitum diets on diabetes risk factors in overweight adults: the DIOGenes multicentre, randomized, dietary intervention trial

BACKGROUND

Dietary regimens providing different levels of protein and glycemic index (GI) foods when prescribed for weight management may also influence insulin sensitivity.

PROCEDURES AND OUTCOMES

Overweight/obese adults in 8 European countries who lost ≥ 8% of initial body-weight (BW) after following a low calorie diet (LCD) were later randomly assigned with a 2x2 factorial design into 4 ad libitum dietary groups with two different protein content levels and dissimilar glycemic index, which were compared to a healthy reference diet. Specific markers assessing insulin resistance were measured. The LCD was initially applied to 932 adults and 773 were randomised to the 5 ad libitum diets. The 6-months programme was completed by 548 participants. The assignment to the Low Protein /High Glycemic Index diet induced a statistically higher HOMA-IR increase during the 6 months period as compared to the control. Contrariwise, the insulin response was lower in the High Protein/Low Glycemic Index diet after 60 and 90 min of an Oral Glucose Tolerance test subsequently carried out after the 6-months intervention. The Low Glycemic Index diets (either with high or low protein content) also lead to a decrease in fructosamine levels during the trial.

CONCLUSION/INTERPRETATION

After a weight loss period, an increase in the dietary protein proportions and a decrease in the consumption of foods with a high Glycemic Index within an ad libitum dietary intervention aiming to weight maintenance produced favorable effects on glycaemic control and insulin sensitivity in overweight/obese subjects.

Glycemic index and glycemic load of carbohydrates in the diabetes diet

Medical nutrition therapy is the first line of treatment for the prevention and management of type 2 diabetes and plays an essential part in the management of type 1 diabetes. Although traditionally advice was focused on carbohydrate quantification, it is now clear that both the amount and type of carbohydrate are important in predicting an individual's glycemic response to a meal. Diets based on carbohydrate foods that are more slowly digested, absorbed, and metabolized (i.e., low glycemic index [GI] diets) have been associated with a reduced risk of type 2 diabetes and cardiovascular disease, whereas intervention studies have shown improvements in insulin sensitivity and glycated hemoglobin concentrations in people with diabetes following a low GI diet. Research also suggests that low GI diets may assist with weight management through effects on satiety and fuel partitioning. These findings, together with the fact that there are no demonstrated negative effects of a low GI diet, suggest that the GI should be an important consideration in the dietary management and prevention of diabetes.

Associations between dairy consumption and body weight: a review of the evidence and underlying mechanisms

As the incidence of obesity is reaching 'epidemic' proportions, there is currently widespread interest in the impact of dietary components on body-weight and food intake regulation. The majority of data available from both epidemiological and intervention studies provide evidence of a negative but modest association between milk and dairy product consumption and BMI and other measures of adiposity, with indications that higher intakes result in increased weight loss and lean tissue maintenance during energy restriction. The purported physiological and molecular mechanisms underlying the impact of dairy constituents on adiposity are incompletely understood but may include effects on lipolysis, lipogeneis and fatty acid absorption. Furthermore, accumulating evidence indicates an impact of dairy constituents, in particular whey protein derivatives, on appetite regulation and food intake. The present review summarises available data and provides an insight into the likely contribution of dairy foods to strategies aimed at appetite regulation, weight loss or the prevention of weight gain.

Breakfast staple types affect brain gray matter volume and cognitive function in healthy children

Childhood diet is important for brain development. Furthermore, the quality of breakfast is thought to affect the cognitive functioning of well-nourished children. To analyze the relationship among breakfast staple type, gray matter volume, and intelligence quotient (IQ) in 290 healthy children, we used magnetic resonance images and applied voxel-based morphometry. We divided subjects into rice, bread, and both groups according to their breakfast staple. We showed that the rice group had a significantly larger gray matter ratio (gray matter volume percentage divided by intracranial volume) and significantly larger regional gray matter volumes of several regions, including the left superior temporal gyrus. The bread group had significantly larger regional gray and white matter volumes of several regions, including the right frontoparietal region. The perceptual organization index (POI; IQ subcomponent) of the rice group was significantly higher than that of the bread group. All analyses were adjusted for age, gender, intracranial volume, socioeconomic status, average weekly frequency of having breakfast, and number of side dishes eaten for breakfast. Although several factors may have affected the results, one possible mechanism underlying the difference between the bread and the rice groups may be the difference in the glycemic index (GI) of these two substances; foods with a low GI are associated with less blood-glucose fluctuation than are those with a high GI. Our study suggests that breakfast staple type affects brain gray and white matter volumes and cognitive function in healthy children; therefore, a diet of optimal nutrition is important for brain maturation during childhood and adolescence.

Soluble fiber dextrin enhances the satiating power of beverages

This study compared the effects of four types of fiber on satiety and energy intakes at the next meal using a standard double-blinded preload study design. Study participants (14 men and 22 women) each took part in 6 study sessions. Study preloads were a combination of a solid snack and a liquid beverage (energy range 0.78-0.83 MJ) containing four different types of fiber: soluble fiber dextrin (12 g), soluble corn fiber (11.8 g), polydextrose (11.8 g), and resistant starch (11.2g). All four fibers were compared to two control conditions of equal volume: an isoenergetic, low-fiber preload and a lower-energy, low-fiber preload. All preloads were presented twice for a total of 0.35-1.65 MJ and 1-24 g fiber. Satiety ratings were collected for 20 min intervals for 220 min during the morning testing session. A test meal was served at 1200 h and plate waste measured. The five higher-energy preloads led to higher fullness and lower hunger ratings compared to the low-energy control but were not significantly different from each other. Relative to the isoenergetic control, only soluble fiber dextrin significantly suppressed energy intakes (p=0.023). Supplementing beverages with soluble fiber dextrin affects short term energy intake and may have implications for weight control.

Pulse consumption, satiety, and weight management

The prevalence of obesity has reached epidemic proportions, making finding effective solutions to reduce obesity a public health priority. One part of the solution could be for individuals to increase consumption of nonoilseed pulses (dry beans, peas, chickpeas, and lentils), because they have nutritional attributes thought to benefit weight control, including slowly digestible carbohydrates, high fiber and protein contents, and moderate energy density. Observational studies consistently show an inverse relationship between pulse consumption and BMI or risk for obesity, but many do not control for potentially confounding dietary and other lifestyle factors. Short-term (≤1 d) experimental studies using meals controlled for energy, but not those controlled for available carbohydrate, show that pulse consumption increases satiety over 2-4 h, suggesting that at least part of the effect of pulses on satiety is mediated by available carbohydrate amount or composition. Randomized controlled trials generally support a beneficial effect of pulses on weight loss when pulse consumption is coupled with energy restriction, but not without energy restriction. However, few randomized trials have been conducted and most were short term (3-8 wk for whole pulses and 4-12 wk for pulse extracts). Overall, there is some indication of a beneficial effect of pulses on short-term satiety and weight loss during intentional energy restriction, but more studies are needed in this area, particularly those that are longer term (≥1 y), investigate the optimal amount of pulses to consume for weight control, and include behavioral elements to help overcome barriers to pulse consumption.

Hyperphagia induced by sucrose: relation to circulating and CSF glucose and corticosterone and orexigenic peptides in the arcuate nucleus

Sucrose-rich diets compared to starch-rich diets are known to stimulate overeating under chronic conditions. The present study in normal-weight rats established an acute "preload-to-test meal" paradigm for demonstrating sucrose-induced hyperphagia and investigating possible mechanisms that mediate this behavioral phenomenon. In this acute paradigm, the rats were first given a small (15 kcal) sucrose preload (30% sucrose) for 30 min compared to an equicaloric, starch preload (25% starch with 5% sucrose) and then allowed to freely consume a subsequent test meal of lab chow. The sucrose preload, when compared to a starch preload equal in energy density and palatability, consistently increased food intake in the subsequent test meal occurring between 60 and 120 min after the end of the preload. Measurements of hormones, metabolites and hypothalamic peptides immediately preceding this hyperphagia revealed marked differences between the sucrose vs starch groups that could contribute to the increase in food intake. Whereas the sucrose group compared to the starch group immediately after the preload (at 10 min) had elevated levels of glucose in serum and cerebrospinal fluid (CSF) along with reduced expressions of neuropeptide Y (NPY) and agouti-related protein (AgRP) in the arcuate nucleus (ARC), the subsequent effects (at 30-60 min) just preceding the test meal hyperphagia were the reverse. Along with lower levels of glucose, they included markedly elevated serum and CSF levels of corticosterone and mRNA levels of NPY and AgRP in the ARC. In addition to establishing an animal model for sucrose-induced hyperphagia, these results demonstrate peripheral and central mechanisms that may mediate this behavioral phenomenon.

The association of general and central obesity with major dietary patterns of adult women living in Tehran, Iran

OBJECTIVES

Using a dietary pattern analysis method could provide more information about the nutritional etiology of chronic diseases such as obesity. The aim of this study is to determine the association between major dietary patterns and general and central obesity among adult women living in Tehran.

MATERIALS AND METHODS

A cross-sectional study was conducted in Tehran, Iran, with 460 women aged 20-50 y. Dietary intake in the previous year was collected by a semi-quantitative food frequency questionnaire. Weight, height and waist circumstance (WC) were measured with standard methods and body mass index (BMI) was calculated. General obesity was defined as BMI > or = 30 kg/m(2) and central obesity as WC > or = 88 cm. Factor analysis was used for identifying major dietary patterns. The association between major dietary patterns and general and central obesity were assessed by logistic regression analysis.

RESULTS

Two major dietary patterns were extracted: "Healthy" and "Unhealthy" dietary patterns. After adjusting for confounders, individuals in the highest quartile of the unhealthy dietary pattern score were more likely to have general (OR=7.33, 95% CI: 2.39-22.51) and central obesity (OR=4.99, 95% CI: 2.08-11.94), whereas, those in the upper quartile of healthy dietary pattern were less likely to have general (OR=0.38, 95% CI: 0.15-0.98) or central obesity (OR=0.33, 95% CI: 0.16-0.71).

CONCLUSION

Our data suggest that a dietary pattern rich in fruit, vegetables, low-fat dairy products and poultry might be negatively associated with obesity. Furthermore our data showed that a dietary pattern high in processed meats, soft drinks, sweets, refined grains, snacks and processed juice might be positively associated with obesity among women aged 20-50 y.

Consuming eggs for breakfast influences plasma glucose and ghrelin, while reducing energy intake during the next 24 hours in adult men

We hypothesized that consuming eggs for breakfast would significantly lower postprandial satiety and energy intake throughout the day. Using a crossover design, 21 men, 20 to 70 years old, consumed 2 isoenergetic test breakfasts, in a random order separated by 1 week. The macronutrient composition of the test breakfasts were as follows: (EGG, % CHO/fat/protein = 22:55:23) and (BAGEL, % CHO/fat/protein = 72:12:16). Fasting blood samples were drawn at baseline before the test breakfast and at 30, 60, 120, and 180 minutes after breakfast. After 180 minutes, subjects were given a buffet lunch and asked to eat until satisfied. Subjects filled out Visual Analog Scales (VAS) during each blood draw and recorded food intake the days before and after the test breakfasts. Plasma glucose, insulin, and appetite hormones were analyzed at each time point. Subjects consumed fewer kilocalories after the EGG breakfast compared with the BAGEL breakfast (P< .01). In addition, subjects consumed more kilocalories in the 24-hour period after the BAGEL compared with the EGG breakfast (P < .05). Based on VAS, subjects were hungrier and less satisfied 3 hours after the BAGEL breakfast compared with the EGG breakfast (P < .01). Participants had higher plasma glucose area under the curve (P < .05) as well as an increased ghrelin and insulin area under the curve with BAGEL (P < .05). These findings suggest that consumption of eggs for breakfast results in less variation of plasma glucose and insulin, a suppressed ghrelin response, and reduced energy intake.

Obesity and the metabolic syndrome: role of different dietary macronutrient distribution patterns and specific nutritional components on weight loss and maintenance

Weight loss and subsequent body weight maintenance are difficult for obese individuals despite the wide variety of dietary regimens and approaches. A substantial body of scientific evidence has shown that by simply varying the macronutrient distribution and composition of dietary factors, weight losses of varying amounts, longer-term body weight maintenance periods, better appetite regulation, and changes in features of the metabolic syndrome can be achieved. At present, renewed efforts are underway to increase the protein content of weight-loss diets, simultaneously restrict fat consumption to no more than 30%, favor polyunsaturated fat, have carbohydrates account for between 40 and 50% of total energy intake, and promote the consumption of low-glycemic foods. The present article reviews the scientific evidence for the effects of several dietary manipulations and sustainable strategies for weight loss and body weight stability as well as for treating specific features of the metabolic syndrome.

Postprandial energy expenditure in whole-food and processed-food meals: implications for daily energy expenditure

Background

Empirical evidence has shown that rising obesity rates closely parallel the increased consumption of processed foods (PF) consumption in USA. Differences in postprandial thermogenic responses to a whole-food (WF) meal vs. a PF meal may be a key factor in explaining obesity trends, but currently there is limited research exploring this potential link.

Objective

The goal was to determine if a particular PF meal has a greater thermodynamic efficiency than a comparable WF meal, thereby conferring a greater net-energy intake.

Design

Subjective satiation scores and postprandial energy expenditure were measured for 5–6 h after isoenergetic meals were ingested. The meals were either ‘whole’ or ‘processed’ cheese sandwiches; multi-grain bread and cheddar cheese were deemed whole, while white bread and processed cheese product were considered processed. Meals were comparable in terms of protein (15–20%), carbohydrate (40–50%), and fat (33–39%) composition. Subjects were healthy women (n=12) and men (n=5) studied in a crossover design.

Results

There were no significant differences in satiety ratings after the two meals. Average energy expenditure for the WF meal (137±14.1 kcal, 19.9% of meal energy) was significantly larger than for the PF meal (73.1±10.2 kcal, 10.7% of meal energy).

Conclusion

Ingestion of the particular PF meal tested in this study decreases postprandial energy expenditure by nearly 50% compared with the isoenergetic WF meal. This reduction in daily energy expenditure has potential implications for diets comprised heavily of PFs and their associations with obesity.

Snacking increased among U.S. adults between 1977 and 2006

This study built on limited knowledge about patterns and trends of adult snacking in the US. We selected adults aged 19 y and older (n = 44,754) between 1977-1978 and 2003-2006 with results weighted and adjusted for sample design effects. Differences testing, by a Student's t test, used STATA 10 (P < or = 0.01). We defined a snacking event as intake of foods over a 15-min period and excluded food defined as snacks but eaten at a meal. Dietary data were obtained from the first 2 d for the 1977-1978 Nationwide Food Consumption Survey (NFCS 77) and the 1989-1991 Continuing Survey of Food Intake by Individuals (CSFII 89); and 2-d dietary data from the 1994-1996 CSFII (CSFII 96) and the NHANES from 2 consecutive surveys: NHANES 2003-2004 and NHANES 2005-2006 (NHANES 03-06). Results showed that snacking prevalence increased significantly from 71 to 97% in 2003-2006 with increases in both the 1989-1994 and the 1994-2006 periods. In all adults, snacking occasions increased 0.97 events over this time period (P < 0.01) and the contribution of snacks to total energy intake increased from 18 to 24% (P < 0.01). The energy density of snacks (food plus beverages) also increased progressively over the time period studied. Important changes in snacking food sources were found among desserts, salty snacks, candies, and sweetened beverages. More research is needed to gain a better understanding of the implications for overall energy intake and energy imbalance.