Body-composition changes in the Comprehensive Assessment of Long-term Effects of Reducing Intake of Energy (CALERIE)-2 study: a 2-y randomized controlled trial of calorie restriction in nonobese humans.
Level 2 - randomized trial
Individual randomized controlled trial
PubMed 28228420 · doi:10.3945/ajcn.116.137232
What was done
In the CALERIE-2 multicenter trial, 218 nonobese adults (BMI 21.9–28.0 kg/m², aged 21–51 years) were randomized 2:1 to a 25% calorie restriction regimen (CR, n = 143) or an ad libitum diet (AL, n = 75) for 2 years. Body weight, waist circumference, fat mass (FM), fat-free mass (FFM), and appendicular mass were measured by dual-energy X-ray absorptiometry at baseline, 12, and 24 months. Activity-related energy expenditure (AREE) was measured by doubly labeled water, and dietary protein intake was assessed by self-report.
What was found
The CR group achieved an 11.9% ± 0.7% caloric deficit over 2 years. Compared with AL controls at 24 months, CR led to significant decreases in body weight (-7.6 ± 0.3 kg vs 0.4 ± 0.5 kg), waist circumference (-6.2 ± 0.4 cm vs 0.9 ± 0.5 cm), FM (-5.4 ± 0.3 kg vs 0.5 ± 0.4 kg), and FFM (-2.0 ± 0.2 kg vs -0.0 ± 0.2 kg; all between-group P < 0.001). As a percentage of body weight, FFM was higher and FM was lower in CR than AL at 24 months. Higher AREE, but not protein intake, predicted FFM preservation (P < 0.01). Men in the CR group lost significantly more trunk fat (P = 0.03) and more FFM as a percentage of weight loss (P < 0.001) than women in the CR group.
Why it matters
This study demonstrates that 2 years of moderate calorie restriction in healthy nonobese humans successfully reduces total and regional adiposity without disproportionate or hazardous loss of lean mass.
Limits
Participants achieved only ~11.9% calorie restriction rather than the prescribed 25% target. Dietary protein intake was measured by self-report. The study included only healthy nonobese adults aged 21–51 years, limiting generalizability to older adults or populations with obesity, and hard clinical longevity outcomes were not measured.
Cited by
- supports The CALERIE study was a two-year randomized controlled trial evaluating a 25% caloric restriction intervention in humans.