Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 2/15/1996
Publication Date: N/A
Technical Abstract: The goal of this study was to determine if time of energy ingestion affected change in body weight or composition during a weight loss program of mild energy restriction and regular exercise. Ten women (BMI +/- SD=28.2 +/- 4.1) completed the residential study comprised of a 3 wk weight stable period followed by a 12 wk weight loss period. Time of ingestion of the diet (7.8 MJ; 59% cho, 19% pro, 22% fat) was varied, with 70% of energy consumed either in the morning (AM) or the evening (PM) for the first 6 wk of the weight loss period. Then subjects were crossed over to the alternate intake pattern for the final 6 wk. Women were weighed daily, and body composition was measured twice weekly by the total body electrical conductivity method. Using ANOVA, there was no significant effect of order on weight or body composition changes. Weight loss (+/- pooled SEM) was greater with AM than with PM intake: 3.52 +/- 0.16 vs. 3.20 +/- 0.16 kg for 6 wk, p<0.05. Body fat loss over 6 wk was not affected by ingestion time: AM= 2.76 +/- 0.20 and PM=2.90 +/- 0.20 kg. FFM loss was greater with AM than PM intake, 0.58 +/- 0.10 vs. 0.18 +/- 0.10 kg, p<0.01. To conclude, ingestion of the bulk of energy in the morning resulted in slightly greater weight loss, whereas evening energy intake was associated with better maintenance of FFM. The lack of a meal time effect on fat loss suggests that there is no metabolic advantage to morning consumption in promoting loss of body energy stores.