Increased plasma levels of glucose-dependent insulinotropic polypeptide are associated with decreased postprandial energy expenditure after modern Japanese meals.

PURPOSE: The nutritional changes that have accompanied the modernization of Japanese dietary patterns have led to significant increases in the number of people who are overweight or obese. This study aimed to clarify the effects of these nutritional changes on postprandial energy expenditure and the release of metabolism-regulating hormones. METHODS: The total daily energy content (20 % breakfast, 40 % lunch, and 40 % dinner) and macronutrient composition (carbohydrate/fat/protein) was 8807.3 kJ and 364.3:30.1:66.4 (g) for the traditional test diet and 9217.6 kJ and 331.7:66.1:76.9 (g) for the modern test diet. In experiment 1, nine healthy Japanese men participated in a crossover study during which they ingested a test diet comprising three meals; postprandial blood parameters were measured after each meal. In experiment 2, another ten men participated in a crossover study during which they ingested 2 meals, after which metabolic responses and blood variables were evaluated. RESULTS: The modern diet induced greater blood levels of glucose-dependent insulinotropic polypeptide (GIP) and ghrelin than did the traditional diet. The expected increase in postprandial energy expenditure (∆REE) tended to be dampened after the modern compared with the traditional diet. GIP was inversely correlated with ∆REE after lunch, and ghrelin was positively associated with ∆REE. CONCLUSION: Both GIP and ghrelin are robust indicators of postprandial energy expenditure. The nutritional changes accompanying the modernization of Japanese dietary patterns may increase the levels of the anabolic intestinal hormone GIP, which is associated with ∆REE, in the Japanese population. The contribution of an increased ghrelin concentration to the decreased ∆REE after the modern diet warrants further investigation.

Frequency of consumption of balanced meals, bodyweight gain and incident risk of glucose intolerance in Japanese men and women: A cohort study.

AIMS/INTRODUCTION: This cohort study assessed the risk for bodyweight gain and development of glucose intolerance based on the frequency of consumption of balanced meals including grain, fish or meat and vegetables. MATERIALS AND METHODS: The participants (8,573 men, 3,327 women) were employees of a company in Japan. A self-administered questionnaire was used to evaluate the frequency of balanced meal consumption. Bodyweight changes and the incidence of glucose intolerance (glycated hemoglobin >6.0%) during the 3-year follow-up period were determined through annual health examinations. RESULTS: The mean bodyweight change over a period of 3 years was 0.78 kg for men and 0.84 kg for women. A lower frequency of balanced meals was associated with a higher bodyweight gain for men (P for trend = 0.004), but not for women. During the study, 464 men and 115 women developed glucose intolerance. Overall, the frequency of balanced meals was not associated with the risk of glucose intolerance in either sex. However, the interaction between the frequency of balanced meals and degree of obesity had a significant effect on the incidence of glucose intolerance in men (P = 0.005), with less frequent consumption of balanced meals being associated with a higher risk for glucose intolerance among men with a BMI ≥25.0 kg/m2 (P for trend = 0.007). CONCLUSIONS: A higher frequency of balanced meals, including grain, fish or meat and vegetable dishes - important components of healthy Japanese food - was associated with a lower risk of glucose intolerance in obese men, but not in non-obese men and women.