Effect of a 3-day high-fat feeding period on carbohydrate balance and ad libitum energy intake in humans.

Objective:A reduction in glycogen after the switch to an isoenergetic high-fat diet (HFD) might promote a compensatory increase in food intake to reestablish carbohydrate balance. We assessed the effect of an isoenergetic switch from a 49%-carbohydrate to 50%-fat diet on nutrient balance and ad libitum food intake. We hypothesized that carbohydrate balance would be inversely related to ad libitum energy intake.Methods:In 47 men and 11 women (22.6±0.4 years; 26.1±0.5 kg m^–2), fuel balance was measured in a respiration chamber over 4 days. During the first day, an isoenergetic, high-carbohydrate diet was provided followed by a 3-day isoenergetic, HFD. At the end of this period and after 16 h of fasting, three options of foods (cookies, fruit salad and turkey sandwich) were offered ad libitum for 4 h. The relationships between post-chamber ad libitum intake and macronutrient oxidation and balance measured day-to-day and over the 4-day respiration chamber stay were studied.Results:After switching to a HFD, 24-h respiratory quotient decreased from 0.87±0.02 to 0.83±0.02 (P<0.0001) resulting in a 4-day cumulative carbohydrate, fat and protein balances of −183±368, 342±480 and 65±267 kcal, respectively. Cumulative energy balance (224±362 kcal per 4 days) did not influence ad libitum energy intake. However, we detected that 4-day carbohydrate balance was a positive and independent predictor of post-chamber ad libitum energy intake (R ²=0.10; P=0.01), whereas no significant influence of fat and protein balances was found.Conclusion:In response to an isoenergetic change from a high-carbohydrate to HFD, higher carbohydrate balance related to increased energy intake. [ABSTRACT FROM AUTHOR]