Effect of diets high or low in unavailable and slowly digestible carbohydrates on the pattern of 24-h substrate oxidation and feelings of hunger in humans

Background: The pattern of substrate utilization with diets containing a hi gh or a low proportion of unavailable and slowly digestible carbohydrates m ay constitute an important factor in the control, time course, and onset of hunger in humans. Objective: We tested the hypothesis that isoenergetic diets differing only in their content of unavailable carbohydrates would result in different tim e courses of total, endogenous, and exogenous carbohydrate oxidation rates. Design: Two diets with either a high (H diet) or a low (L diet) content of unavailable carbohydrates were fed to 14 healthy subjects studied during tw o 24-h periods in a metabolic chamber. Substrate utilization was assessed b y whole-body indirect calorimetry. In a subgroup of 8 subjects, endogenous and exogenous carbohydrate oxidation were assessed by prelabeling the body glycogen stores with [C-13]carbohydrate. Subjective feelings of hunger were estimated with use of visual analogue scales. Results: Total energy expenditure and substrate oxidation did not differ si gnificantly between the 2 diets. However, there was a significant effect of diet (P = 0.03) on the carbohydrate oxidation pattern: the H diet elicited a lower and delayed rise of postprandial carbohydrate oxidation and was as sociated with lower hunger feelings than was the L diet. The differences in hunger scores between the 2 diets were significantly associated with the d ifferences in the pattern of carbohydrate oxidation among diets (r = -0.67, P = 0.006). Exogenous and endogenous carbohydrate oxidation were not signi ficantly influenced by diet. Conclusions: The pattern of carbohydrate utilization is involved in the mod ulation of hunger feelings. The greater suppression of hunger after the H d iet than after the L diet may be helpful, at least over the short term, in individuals attempting to better control their food intake.