Energy expenditure and net substrate utilization in men ingesting usual and high amounts of nonstarch polysaccharide

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.

We determined whether energy expenditure and fuel selection differ when men consume a diet intrinsically higher in NSP than a usual mixed diet.

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).

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).

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.