The Effects of Continuous vs. Intermittent Caloric Restriction on Fat Loss: A Randomized Controlled Trial.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 42280466 · doi:10.3390/nu18111823
What was done
Thirty adult women with obesity (ages 18–65, BMI 30–45 kg·m⁻²) completed a 2-week maintenance baseline to determine energy requirements and were randomized to 12 weeks of continuous caloric restriction (CCR) or intermittent restriction incorporating structured diet refeeds and diet breaks (DRF). Both groups were prescribed a 25% caloric deficit and 1.2 g·kg⁻¹·day⁻¹ protein. Body fat percentage, fat mass, and fat-free mass were measured before and after the intervention using air-displacement plethysmography.
What was found
Both groups significantly reduced fat mass (CCR: -9.30 ± 2.77 kg; DRF: -9.21 ± 2.63 kg; between-group p > 0.05, Cohen's d = 0.03) and body fat percentage (CCR: -6.7 ± 2.1%; DRF: -6.0 ± 1.9%; group × time p > 0.05). Fat-free mass increased over time across all participants (p < 0.05), with a nonsignificant trend toward greater preservation in the DRF group (group × time p = 0.08). The CCR group achieved a significantly greater daily energy deficit than DRF (-1005 ± 515 vs. -690 ± 120 kcal·day⁻¹, p = 0.041).
Why it matters
Incorporating structured diet breaks achieves equivalent fat loss to continuous caloric restriction in women with obesity despite a smaller average daily energy deficit. This strategy may help mitigate lean mass loss without compromising weight reduction goals.
Limits
The study sample was small (n = 30) and restricted exclusively to adult females, limiting generalizability to males. The 12-week intervention was not adequately powered to confirm whether the observed trend in fat-free mass preservation or metabolic adaptation differences were statistically significant.