Background: It has been suggested that hunger may be delayed and food intake reduced under metabolic conditions that spare carbohydrate oxidation.
Objective: Our objective was to examine the role of glucose metabolism in the control of food intake in men by using medium-chain triacylglycerols (MCTs) to spare carbohydrate oxidation.
Design: In 10 male volunteers, isolated and deprived of any time cues, we studied the effects of 4 lunches on hunger ratings, the duration of satiety, the amount of food ingested at dinner, energy expenditure, substrate oxidation, and plasma variables until the time of the dinner request. One lunch was a basic 2310-kJ meal containing 40 kJ fat substitute (Sub lunch). The 3 other lunches consisted of the same basic meal supplemented with either 1200 kJ long-chain triacylglycerols (LCT lunch), 1200 kJ MCTs (MCT lunch), or 900 kJ carbohydrate plus 300 kJ LCTs (Cho lunch).
Results: Energy expenditure was not significantly different after the different lunches, but carbohydrate oxidation was lower after the MCT and LCT lunches than after the Cho lunch. Fat oxidation was greater after the MCT and LCT lunches. The time of the dinner request was significantly delayed after the Cho lunch. Food intake at dinner was significantly lower after the MCT lunch than after the Sub and Cho lunches, but the dinner meal request was not delayed.
Conclusion: Carbohydrate may have a greater role in the duration of satiety than does fat, but MCTs may play an active role in other aspects of the control of food intake, especially in satiation at the next meal.