Fat loss depends on energy deficit only, independently of the method for weight loss.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 18025815 · doi:10.1159/000111162
What was done
Twenty non- or moderately obese women (mean age 27.3 ± 6.6 years, BMI 24.32 ± 3.11 kg/m²) were randomized to an 8-week mild hypocaloric intervention using one of two isocaloric energy deficit strategies: diet alone (D; deficit of -2,095 ± 659 kJ/day) or diet plus aerobic exercise (DE; diet deficit of -1,420 ± 1,084 kJ/day plus three 60-minute sessions per week at 60% VO2max, corresponding to -5,866 kJ/week). Evaluated outcomes included body mass, body fat, lipid profile (total cholesterol, HDL-C, LDL-C, triglycerides), submaximal exertion heart rate and blood lactate at 100 W, and maximum exercise performance in watts.
What was found
Body mass and body fat decreased significantly in both groups (D: -1.95 ± 1.13 kg and -1.47 ± 0.87%, p < 0.05; DE: -2.23 ± 1.28 kg and -1.59 ± 0.87%, p < 0.05), with no significant difference observed between groups. Total cholesterol, HDL-C, LDL-C, triglycerides, and heart rate during 100 W exertion showed no significant changes. Lactate accumulation during 100 W exertion decreased significantly in DE (-0.8 ± 1.4 mmol/L, p < 0.05) and increased in D (+0.4 ± 0.5 mmol/L, p < 0.05). Maximum exercise performance increased significantly in DE (+12.2 ± 8.8 W, p < 0.05) and showed no significant change in D.
Why it matters
This study shows that fat and weight reduction are determined by the magnitude of the negative energy balance rather than whether the deficit is created by dietary restriction alone or combined with exercise, though exercise is necessary to improve exercise capacity.
Limits
The sample size is very small (n = 20 total), limiting statistical power. The study was conducted only in young, non- or moderately obese females over a short 8-week period, which limits generalizability to males, older populations, and individuals with severe obesity.
Cited by
- supports A caloric deficit is required for fat loss.