Fat loss depends on energy deficit only, independently of the method for weight loss

Background: This study was designed to compare the effects of 2 different but isocaloric fat reduction programs with the same amount of energy deficit - diet alone or diet combined with aerobic training - on body composition, lipid profile and cardiorespiratory fitness in non- or moderately obese women.

Methods: Twenty non- or moderately obese (BMI 24.32 +/- 3.11) females (27.3 +/- 6.6 years) were tested at the beginning and after an 8-week period of a mild hypocaloric diet for the following parameters: (1) body mass and body fat; (2) total cholesterol, HDL-C, LDL-C and triglycerides; (3) lactate (millimol/liter) during submaximal exertion (100 W); (4) heart rate during submaximal exertion (100 W), and (5) maximum exercise performance (watt). Subjects were randomly divided into either a diet alone (D, -2,095 +/- 659 kJ/day) or a diet (-1,420 +/- 1,084 kJ/day) plus exercise (DE, three 60-min sessions per week at 60% of VO(2)max or -5,866 kJ/week) group.

Results: Body mass and body fat decreased significantly in D (-1.95 +/- 1.13 kg or -1.47 +/- 0.87%; p < 0.05) and DE (-2.23 +/- 1.28 kg or -1.59 +/- 0.87%; p < 0.05), but there was no significant difference observed between the groups. Statistical analysis revealed no significant changes of total cholesterol, HDL-C, LDL-C, triglycerides and heart rate during submaximal exertion (100 W). Lactic acid accumulation during submaximal exertion (100 W) decreased significantly (-0.8 +/- 1.4 mmol/l, p < 0.05) in DE and increased significantly (+0.4 +/- 0.5 mmol/l, p < 0.05) in D. Maximum exercise performance improved significantly (+12.2 +/- 8.8 W, p < 0.05) in DE and did not change significantly in D.

Conclusions: This study showed that independently of the method for weight loss, the negative energy balance alone is responsible for weight reduction.