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/m(2)) 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.
|Journal||Applied Physiology Nutrition and Metabolism-Physiologie appliquee nutrition et metabolisme|
|Publication status||Published - 1 Jan 2013|