Diet-Induced thermogenesis: comparison of two isocaloric meal-replacement shakes. A pilot study

Abstract

The aim of this study is to evaluate the differences in diet-induced thermogenesis (DIT) between two liquid meal-replacement shakes of different macronutrient compositions: high protein (HP) and high carbohydrate (HC) meal. Five male subjects (26 ± 3.7 y, body mass index 24.6 ± 1.7 kg·m-2) completed the crossover, single-blind study. During two separate occasions (non-consecutive days) indirect calorimetry measurement was taken. Production of CO2, consumption of O2 and respiratory exchange ratio were monitored before and after ingestion of two isocaloric liquid meals with energy content of 7 kcal/kg per fat free weight. The postprandial period measurement lasted 180 min. Nonparametric statistics was used and value of 0.05 was accepted as the limit of significance. An immediate and persistent thermic effect was caused by the test meals. The total DIT calculated in HP and HC meals was: 51.8 ± 17.2 kcal/180 min and 32.13 ± 13.4 kcal/180 min, respectively (where p = 0.14). No statistically significant difference in postprandial energy expenditure between HP (0.29 ± 0.10 kcal·min-1) and HC (0.18 ± 0.07 kcal·min-1) meals was observed (where p = 0.14). Elevated values of energy expenditure did not return to the baseline after 3 hours. The DIT, expressed as percentage of energy consumed, averaged 8.7 ± 2.9 % for the HP meal, compared to 5.4 ± 2.3 % for the HC meal (where p = 0.14). Results indicate that the macronutrient composition plays a significant role in metabolic responses. It was concluded that an increment in the energy expenditure above the baseline after ingestion of either protein-like or maltodextrin-like test meals is comparable.