Background: Diets intrinsically high in nonstarch polysaccharides (NSPs) are frequently advised for body weight regulation and health, but the consequences for energy expenditure and fuel selection are undetermined.
Objective: We determined whether energy expenditure and fuel selection differ when men consume a diet intrinsically higher in NSP than a usual mixed diet.
Design: A randomized crossover design was used in which 12 healthy men were fed a maintenance diet for approximately 3 wk in a metabolic suite. By judicial choice of food exchanges, the usual- and high-NSP diets were similar in protein, fat, and carbohydrate contents. Twenty-four-hour, indirect, open-circuit calorimetry was performed, including measurements of total hydrogen gas and methane. Participants were weight stable (within 2 kg for 3 wk), entered an 11-m3 calorimetry chamber for 36 h with measurements taken in the last 24 h, and underwent a strictly controlled program of moderate physical activity (1.3 x basal metabolic rate).
Results: The mean total 24-h energy expenditure and percentages from protein, fat, and carbohydrate metabolism were 10 MJ/d and 16%, 35%, and 48%, respectively. Differences (mean+/-SEM) between the 2 diets were only -0.005+/-0.130 MJ/d, -0.3+/-1.3%, -0.2+/-2.0%, and 0.6+/-2.2%, respectively, and were nonsignificant (P> 0.2).
Conclusions: There was no thermogenic response to the high-NSP diet, which would be advantageous for body weight control, and no short-term influence on body composition, as may be judged from a lack of change in protein, fat, or carbohydrate metabolism.