Substrate oxidation influences liking, wanting, macronutrient selection, and consumption of food in humans.

BACKGROUND Several carbohydrate-based models of feeding have been described. The influence of the substrate oxidation rate on liking, wanting, and macronutrient selection, however, is not known in humans. OBJECTIVE The aim of this study was to investigate the influence of the substrate oxidation rate on the above variables. DESIGN A randomized 4-condition study was conducted in 16 normal-weight men (mean ± SD age: 23 ± 3 y). The sessions differed in the composition of breakfast, which was either high in carbohydrates (HC) or low in carbohydrates (LC) or high in fat (HF) or low in fat (LF). Two hours and 20 minutes after breakfast, energy expenditure (EE) and respiratory exchange ratios (RERs) were measured. Next, olfactory liking for 4 foods (sweet and fatty) and ad libitum energy intake (carbohydrate- and fat-rich bread) were evaluated. RESULTS EE was higher (P < 0.001) and subsequent intake was lower (P < 0.01) after the HC and HF breakfasts than after the LC and LF breakfasts. The HC and LC breakfasts induced a higher RER (P < 0.001), lower olfactory liking for sweet foods (P < 0.05), and the consumption of a lower proportion of carbohydrate-rich bread (P< 0.05) than did the HF and LF breakfasts. The HF breakfast induced the lowest RER (P < 0.001), the lowest olfactory liking for fatty foods (P < 0.05), and the lowest proportion of fat-rich bread consumed (P < 0.01). Above all, a negative correlation was found between the RER and olfactory liking for sweet foods (P < 0.001). CONCLUSION A high fat oxidation rate induces a strong liking for carbohydrates and a low liking for fats, which lends new support to the carbohydrate-based model of feeding. This trial is registered at clinicaltrials.gov as NCT01122082.