Spontaneous weight loss during 11 weeks' ad libitum intake of a low fat/high fiber diet in young, normal weight subjects.

OBJECTIVE: During the first 11 weeks of 8 months' ad libitum intake of a low fat/high fiber diet (25.5 energy-% fat, 58.5 energy-% carbohydrate, 3.9 g dietary fiber/MJ) primarily aimed at investigating the effect on blood lipids, spontaneous, unintended body weight changes occurred. The objective of the present paper was to elaborate the analyses on changes in body weight and composition during the 11 weeks' intervention period. MEASUREMENTS: Dietary intake, body weight and composition. SUBJECTS: Subjects in the intervention (I) (n = 24) and control group (C) (n = 24) were normal weight, young, healthy students. RESULTS: In the intervention group an overall decrease in body weight (-1.3 +/- 0.4 kg) (mean +/- s.e.m.) (P < 0.01) and fat mass (-1.6 +/- 0.2 kg, P < 0.001) occurred. Fat free mass remained unchanged (0.1 +/- 0.3 kg, n.s.). Subjects with the initially lowest level of body fat (n = 10) gained fat-free mass (0.6 +/- 0.2 kg) (n.s.) and lost fat mass (-0.9 +/- 0.2) (P < 0.01). In the intervention group initial body weight and fat mass correlated significantly to change in body weight (r = -0.59, P = 0.003 and r = -0.53, P = 0.008) and fat mass (r = -0.52, P = 0.01, and r = -0.50, P = 0.01). No changes were observed in the control group. CONCLUSION: The ad libitum intake of a low fat/high fiber diet lead to a spontaneous loss of body weight and fat mass in young, normal weight subjects.