The Short-term Effect of a Balanced Deficit Diet on Resting Energy Expenditure.

Abstract

PURPOSE: To examine the change in REE in response to weight loss across a 4-week period in overweight and obese males and females compared with a no treatment control. METHODS: Thirty-seven subjects (body mass index 25.0-39.9kg/m2; males = 14, females = 23) participated in a 4-week intervention with random assignment to an Experimental Group or a no treatment Control Group. The experimental group was instructed to reduce energy intake to 1200–1500 kcal/d and participate in 100 min/wk of moderate aerobic exercise. The control group was instructed to maintain current eating and exercise behaviors. Assessments were conducted at 0 and 4 weeks. REE was assessed using the dilution technique, and was expressed as absolute REE (kcal/ d), REE relative to body weight, (kcal/kg/d), REE relative to lean body mass (kcal/kgLBM/d). Body weight was assessed using a calibrated scale and lean body mass was assessed using bioelectrical impedance analysis. RESUITS: Thirty-five subjects completed the study (94.6%). There were significant differences (p<0.05) for change in outcomes between the experimental and control groups for body weight (−3.3+1.7 vs. 0.6+1.1 kg) lean body mass (−0.6+0.9 vs. 0.2+0.9 kg), absolute REE (−205.8+193.0 vs. −11.4+ 140.6 kcal/d), and REE relative to lean body mass (−3.3+2.9 vs. −0.4+2.6 kcal/kgLBM/d). There as a trend toward a significant difference between the groups (p = .07) for REE relative to body weight (−1.4+1.9 vs. −0.3+1.5 kcal/kg/d). When the groups were combined, there was a correlation between change in REE and change in body weight was r=0.41 (p<.05), and change in REE and change in lean body mass was r=0.44 (p<.01). CONCLUSIONS: Results indicate that absolute and relative REE are significantly reduced in response to weight loss over a 4-week intervention period, and this may affect subsequent patterns for weight change. However, the modest correlations between change in REE and change in both body weight and lean body mass may suggest that additional physiological mechanisms may influence REE during the acute phase of weight loss. Thus, future studies should examine the influence of other physiological and metabolic mechanisms on REE during weight loss.