Prolongation of satiety after low versus moderately high glycemic index meals in obese adolescents

Meal glycaemic load of normal-weight and overweight Hong Kong children

OBJECTIVE

To describe the pattern of meal glycaemic load of children in Hong Kong and to determine whether the meal glycaemic load is associated with childhood overweight.

METHOD

Dietary records (3-day) of 316 Hong Kong children aged 6-7 years were collected. Glycaemic load was calculated from the estimated weight (WT), carbohydrate content (%CHO) and glycaemic index (GI) of each food taken using the equation: (% CHO x GI x WT/100). The meal glycaemic load was then the sum of the glycaemic loads of all food taken in each meal. Logistic regression analyses were used to compare the average meal glycaemic load (of breakfast, lunch and dinner) and other dietary parameters between overweight children and normal-weight children.

RESULTS

Breakfast, lunch, dinner and snacks provided, respectively, 17, 29, 29 and 25% of the total glycaemic load in a day. White rice (excluding congee (rice porridge) and glutinous rice) contributed almost half of the total glycaemic load. Adjusted logistic regression showed that the meal glycaemic load was not significantly associated with childhood overweight after adjusting for parental obesity, birth weight, sleeping duration, mean energy intake and paternal smoking.

CONCLUSION

Meal glycaemic load calculated from current diet was not an independent factor associated with childhood overweight in children aged 6-7 years. Our data suggested that modifying the type of rice/staple consumed and choosing low-GI snacks could have a major influence on the total meal glycaemic load of young Hong Kong children.

Diet induced weight loss accelerates onset of negative alliesthesia in obese women

BACKGROUND

The physiological and behavioral responses to hypocaloric diet are to increase energy intake to defend a steady body weight. We utilized the method of "negative alliesthesia" for measuring the hedonic reponse to sweet stimulus before (Initial session) and 3 months after entering a weight loss program. The negative alliesthesia test is known by physiologists but few clinical data exist. It is based on the observation that repeated pleasant gustatory stimuli turn into unpleasantness in the process of alliesthesia. At first visit participants repeatedly ingested sweet stimuli until they found them unpleasant and rated quantitatively on a linear analogue scale their hedonic experience. This procedure was repeated every 3 min until participants felt displeasure to end the session. The same protocol was followed after three months of following a weight loss diet. Dieting energy intake was from 1400 - 2000 kcal/d for 8 wk. Energy composition was 50% carb:25% prot: 25% lipid. After 8 wk caloric intake increased by 50 kcal/wk, to reach daily intake of 1800 - 2400 kcal/d. Energy composition was 50% carb:22% prot: 27% lipid. We report results on the effect of slow weight loss on negative alliesthesia in ten obese female participants enrolled in a commercial diet program based on Canada's Food Guide (Mincavi).

RESULTS

Results showed that diet lowered the mean BMI (Initial session 36.8 +/- 1.8 vs. 3 mo 34.9 +/- 1.8 kg/m2). At 3 mo the onset of negative alliesthesia, time to abandon experimental session, was shortened (Initial session 33 vs. 3 mo 24 min). The same trend was observed in the time to reach indifference (Initial session 21.9 +/- 3.8 vs. 3 mo 16.2 +/-2.4 min). There was no observed difference in maximum (Initial session +79.5 +/- 11.7; 3 mo +94.5 +/- 9.9 mm) and minimum (Initial session -90.0 +/- 14.4; 3 mo -106 +/- 11.1 mm) hedonic rating.

CONCLUSION

Earlier onset of negative alliesthesia, as seen in our participants, is not consistent with previous hedonic studies that showed delayed or absent negative alliesthesia in participants when below their initial body weight. Therefore, it is hypothesized that the accelerated onset of negative alliesthesia observed in our obese participants after weight loss is suggestive of a lowered body weight set-point. Factors inherent to the weight loss diet studied here, such as mild energetic restriction, lowered palatability, and diet composition, may have played a role in this experimental outcome.

Are all calories created equal? Emerging issues in weight management

The global prevalence of overweight and obesity is growing. Correction of the problem through dietary intervention has been disappointing and has prompted research into variations of diet composition or pattern to promote negative energy balance. Limited research suggests that selected approaches, such as low-carbohydrate diets, augment weight loss and offer an advantage over conventional low-fat diets. This has led to the hypothesis that although in theoretical terms a calorie is a calorie, in practice this is not the case. Support for such views and plausible mechanisms exist. Although any advantage may augment weight management, reported discrepancies between theoretical and observed effects are small. Thus, energy-restricted diets should be based primarily on energy intake and expenditure.

Influence of glycemic index/load on glycemic response, appetite, and food intake in healthy humans

OBJECTIVE

High glycemic index (GI)/load (GL) diets reportedly enhance appetite and promote positive energy balance. Support for this hypothesis stems largely from acute feeding trials and longer-term studies lacking control over the macronutrient composition and palatability of test foods. This study evaluated the effects of consuming high- and low-GI/GL meals, matched on macronutrient composition and palatability, plasma glucose and insulin, appetite, and food intake.

RESEARCH DESIGN AND METHODS

Thirty-nine healthy adults consumed only low- or only high-GI foods ad libitum in the laboratory for 8 days in either high (three foods per meal)- or low (one food per meal)-variety conditions. Glucose and insulin concentrations as well as appetitive sensations were determined before and for 2 h following breakfast and lunch on days 1 and 8. Energy intake was monitored daily.

RESULTS

There were no significant differences in plasma glucose or insulin responses, appetitive ratings, or food intake between treatments.

CONCLUSIONS

These data indicate that the differential glycemic response of foods tested in isolation under fixed time are not preserved under conditions of chronic ad libitum consumption of mixed meals.

Carbohydrates and dietary fiber

The most widely spread eating habit is characterized by a reduced intake of dietary fiber, an increased intake of simple sugars, a high intake of refined grain products, an altered fat composition of the diet, and a dietary pattern characterized by a high glycemic load, an increased body weight and reduced physical activity. In this chapter the effects of this eating pattern on disease risk will be outlined. There are no epidemiological studies showing that the increase of glucose, fructose or sucrose intake is directly and independently associated with an increased risk of atherosclerosis or coronary heart disease (CHD). On the other hand a large number of studies has reported a reduction of fatal and non-fatal CHD events as a function of the intake of complex carbohydrates--respectively 'dietary fiber' or selected fiber-rich food (e.g., whole grain cereals). It seems that eating too much 'fast' carbohydrate [i.e., carbohydrates with a high glycemic index (GI)] may have deleterious long-term consequences. Indeed the last decades have shown that a low fat (and consecutively high carbohydrate) diet alone is not the best strategy to combat modern diseases including atherosclerosis. Quantity and quality issues in carbohydrate nutrient content are as important as they are for fat. Multiple lines of evidence suggest that for cardiovascular disease prevention a high sugar intake should be avoided. There is growing evidence of the high impact of dietary fiber and foods with a low GI on single risk factors (e.g., lipid pattern, diabetes, inflammation, endothelial function etc.) as well as also the development of the endpoints of atherosclerosis especially CHD.

Effect of glycemic index on whole-body substrate oxidation in obese women

BACKGROUND

Glycemic index is hypothesized to determine fuel partitioning through serum plasma insulin modifications induced by dietary carbohydrates, thereby modulating fat accretion or oxidation.

OBJECTIVE

To assess the glycemic effects on postprandial fuel oxidation and blood response.

DESIGN

In all, 12 obese women were fed on a randomized crossover design with two test meals (breakfast+lunch). High- or low-glycemic meals were provided on separate days. Energy intake on high-glycemic meal was 7758+/-148 kJ and for low-glycemic meal was 7806+/-179 kJ. Carbohydrates supplied were 273+/-5 and 275+/-6 g, respectively. Macronutrient distribution was 55% carbohydrates, 30% fat and 15% protein. Fuel oxidation was measured continuously in a respiratory chamber for 10 h. Serum glucose, free fatty acids (FFA), insulin and glucagon samples were taken for 5 h after breakfast.

RESULTS

Glucose AUC changed significantly in response to different glycemic breakfast. Low- vs high-glycemic breakfast was 211+/-84 and 379+/-164 mmol/l (P<0.05). Similarly, insulin changed from 94+/-37 and 170+/-87 nmol/l (P<0.05), respectively. The rate of increment for serum glucose and insulin reached by the high- vs low-glycemic meal was 1.8 times more with the high-glycemic breakfast. Serum FFA were similarly suppressed by both meal types by 3 h after meal intake, but then raised significantly more with the low-glycemic meal by the fourth and fifth hour (P<0.05). Plasma glucagon did not show a significant variation with glycemic index. Carbohydrate and fat oxidation was not modified by glycemic meal characteristics, being virtually the same for low- vs high-glycemic comparisons in the 5 h following breakfast and lunch (P=NS).

CONCLUSION

This study demonstrates that dietary glycemic characteristics were unable to modify fuel partitioning in sedentary obese women.

Carbohydrate and weight control: where do we stand?

PURPOSE OF THE REVIEW

The Atkins diet has been criticized and vilified by much of the scientific community since it was proposed 30 years ago, because it challenged nutritional recommendations and dietary guidelines for a healthy diet. However, in spite of such recommendations the prevalence of obesity continues to rise. The present review evaluates recent scientific evidence and attempts to reach consensus on the confusion of weight-reducing diets.

RECENT FINDINGS

Many dietary macronutrient paradigms have been proposed for the treatment of obesity. Since obesity in its dynamic phase is the result of energy intake exceeding energy expenditure, intuitively to lose weight energy intake should be less than energy expenditure, and one might expect that the macronutrient composition of the diet would have very little, if any, effect. However, short- and long-term therapies with low-carbohydrate or high-protein diets appear to offer advantages over conventional weight-loss regimens for weight loss, body composition and cardiovascular risk factors.

SUMMARY

Low-carbohydrate, Atkins-type diets have been demonstrated to have positive effects on weight loss and biomarkers of cardiovascular risk, which has prompted some researchers to question the validity of present-day dietary guidelines. Although evidence is accumulating in their favour, the safety and efficacy of low-carbohydrate, high-protein diets needs further long-term verification.

A Pilot Study to Determine the Feasibility of the Low Glycemic Index Diet as a Treatment for Overweight Children in Primary Care Practice

BACKGROUND

The prevalence of overweight children is increasing. Experimental evidence and specialty clinic trials suggest that a low glycemic index (LGI) diet could be an effective primary care-based treatment for overweight children.

OBJECTIVE

Conduct a pilot study to determine whether parents of overweight children can lower the glycemic index (GI) of their child's diet after receiving brief instructions and a handout from their pediatrician; and the diet's impact on body mass index (BMI).

PATIENTS

Children 5-12 years with BMIs greater than the 95th percentile.

INTERVENTION

Brief description of the LGI diet and a handout categorizing foods based on their GI and sample meals.

DESIGN

Nonrandomized, 12-week pilot study.

MEASURES

BMI, 24-hour recall, and food frequency questionnaire (FFQ) at entry; 3-day food records at 3, 6, and 9 weeks; BMI, FFQ, and questionnaire at 12 weeks. A GI score derived from standard GI tables.

RESULTS

Of 34 children initially enrolled, 15 completed the study. Of these, 14 lowered their GI score (mean initial score = 26.6; mean score at 12 weeks 15.6; P <.0001). Mean daily carbohydrate (CHO) intake decreased by 73 g over the study period (P <.02), and mean daily caloric intake decreased by 292 kcal (P <.02). All 15 parents described the diet as easy to understand; 10 reported that their child was generally able to follow the diet. BMI Z-score decreased in 12 of 15 children.

CONCLUSION

This pilot study suggests that implementing the LGI diet is feasible in primary care for some patients. Further study is warranted with larger study and comparison groups.

Low glycemic index breakfasts and reduced food intake in preadolescent children

OBJECTIVE

Recent reports have suggested that a low glycemic index (GI) diet may have a role in the management of obesity through its ability to increase the satiety value of food and modulate appetite. To date, no long-term clinical trials have examined the effect of dietary GI on body weight regulation. The majority of evidence comes from single-day studies, most of which have been conducted in adults. The purpose of this study was to investigate the effect of 3 test breakfasts-low-GI, low-GI with 10% added sucrose, and high-GI-on ad libitum lunch intake, appetite, and satiety and to compare these with baseline values when habitual breakfast was consumed.

METHODS

A 3-way crossover study using block randomization of breakfast type was conducted in a school that already ran a breakfast club. A total of 37 children aged 9 to 12 years (15 boys and 22 girls) completed the study. The proportion of nonoverweight to overweight/obese children was 70:30. Children were divided into 5 groups, and a rolling program was devised whereby, week by week, each group would randomly receive 1 of 3 test breakfasts for 3 consecutive days, with a minimum of 5 weeks between the test breakfasts. Participants acted as their own control. The 3 test breakfasts were devised to match the energy and nutritional content of an individual's habitual breakfast as far as possible. All test breakfasts were composed of fruit juice, cereal, and milk with/without bread and margarine; foods with an appropriate GI value were selected. After each test breakfast, children were instructed not to eat or drink anything until lunchtime, except water and a small serving of fruit supplying approximately 10 g of carbohydrate, which was provided. Breakfast palatability, satiation after breakfast, and satiety before lunch were measured using rating scales based on previously used tools. Lunch was a buffet-style meal, and children were allowed free access to a range of foods. Lunch was served in the school hall where the rest of the schoolchildren were eating. Food intake at lunch was unobtrusively observed and recorded. Leftovers and food swapping were recorded, and plate waste was estimated. Lunch intakes were analyzed using a multilevel regression model for repeated measures data. The likelihood ratio statistic was used to determine whether the type of breakfast eaten had a significant effect on lunch intake after allowing for sex and weight status.

RESULTS

The type of breakfast eaten had a statistically significant effect on mean energy intake at lunchtime: lunch intake was lower after low-GI and low-GI with added sucrose breakfasts compared with lunch intake after high-GI and habitual breakfasts (which were high-GI). Overweight and sex did not have a significant effect on lunch intake. Pairwise comparisons among the 3 types of test breakfasts and between each test breakfast and habitual breakfast were made. Lunch intake after the high-GI breakfast was significantly higher than after the low-GI breakfast and low-GI breakfast with added sucrose. The details of the pairwise comparisons were as follows: high-GI versus low-GI = 145 +/- 54 kcal; high-GI versus low-GI plus sucrose = 119 +/- 53 kcal; low-GI plus sucrose versus low-GI = 27 +/- 54 kcal. Lunch intake after the low-GI breakfast and the low-GI breakfast with added sucrose was significantly lower than after the habitual breakfast. The details of the pairwise comparisons were as follows: low-GI versus habitual = -109 +/- 75 kcal; low-GI plus sucrose versus habitual = -83 +/- 75 kcal; high-GI versus habitual = 36 +/- 75 kcal. There were no significant differences between the test breakfasts in immediate satiation. The high-GI breakfasts were rated to be more palatable than the low-GI breakfasts. At lunchtime, hunger ratings were greater after the high-GI breakfast compared with the other 2 test breakfasts on 2 of the 3 experimental days. Prelunch satiety scales were inversely related to subsequent food intake.

CONCLUSIONS

These results suggest that low-GI foods eaten at breakfast have a significant impact on food intake at lunch. This is the first study to observe such an effect in a group of normal and overweight children and adds to the growing body of evidence that low-GI foods may have an important role in weight control and obesity management. The potentially confounding effect of differences in the macronutrient and dietary fiber content of the test breakfasts warrants additional study. In addition, the impact of GI on food intake and body weight regulation in the long term needs to be investigated.