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.

Consumption of a controlled low-fat diet containing olestra for 9 months improves health risk factors in conjunction with weight loss in obese men: the Ole' Study.

OBJECTIVE: To compare the effects of a standard American diet, a traditional low-fat diet, and a low-fat diet containing the fat substitute olestra on risk factors for heart disease and diabetes. DESIGN: A 9-month, double-blind, randomized, parallel-arm, feeding study comparing three diets: (1). control (33% fat), (2). fat-reduced (FR; 25% fat), and (3). fat-substituted (FS) where olestra replaced 1/3 of dietary fat (33% lipid and 25% digestible fat). Subjects were allowed to adjust their total energy intake as desired, allowing weight to fluctuate. SUBJECTS: A total of 37 healthy, obese men (age 36.7+/-1.3 y; body mass index 30.8+/-0.4 kg/m(2)). MEASUREMENTS: Body weight and composition by dual-energy X-ray absorptiometry, blood pressure, serum lipids, lipoproteins, hemostatic factors, glucose, insulin, and leptin at baseline and every 3 months. RESULTS: The FS group lost 6.27 kg of body weight by 9 months vs 4.0 kg in the control and 1.79 kg in the FR groups. There was a significant diet main effect on cholesterol (P=0.002), low-density lipoprotein cholesterol (P=0.003), and triglycerides (P=0.01), all of which decreased in the FS group but not the other groups by 9 months. Apolipoprotein B (ApoB) increased in the FR and control groups but was unchanged in the FS group (diet main effect P=0.04). High-density lipoprotein (HDL) cholesterol increased in all groups over 9 months (time main effect P=0.0001). Time main effects were also observed for cholesterol, ApoA1, ApoB, Factor VII, diastolic blood pressure, and glucose. After adjustment for % fat loss at 9 months, the effects of diet on change in risk factors remained significant only for triglycerides. DISCUSSION: Consumption of a low-fat diet containing olestra for 9 months produced significant improvement in cardiovascular risk factors, an effect largely explained by weight loss. Long-term low-fat diet consumption with or without olestra does not decrease HDL cholesterol.