Insufficient sleep undermines dietary efforts to reduce adiposity.
Level 2 - randomized trial
Individual randomized crossover trial
PubMed 20921542 · doi:10.7326/0003-4819-153-7-201010050-00006
What was done
Ten overweight nonsmoking adults (3 women and 7 men, mean age 41 years, mean BMI 27.4 kg/m²) completed a randomized, 2-period, 2-condition crossover study in a clinical research center and sleep laboratory. Participants underwent 14 days of moderate caloric restriction with either 8.5 hours or 5.5 hours of nighttime sleep opportunity. The primary outcome was loss of fat and fat-free body mass; secondary measures included substrate utilization, energy expenditure, hunger, and 24-hour metabolic hormone concentrations.
What was found
Compared with 8.5 hours of sleep opportunity, 5.5 hours decreased the proportion of weight lost as fat by 55% (0.6 kg vs. 1.4 kg; P = 0.043) and increased the loss of fat-free body mass by 60% (2.4 kg vs. 1.5 kg; P = 0.002). Sleep curtailment was also accompanied by markers of enhanced neuroendocrine adaptation to caloric restriction, increased hunger, and a shift toward oxidizing less fat.
Why it matters
This trial demonstrates that insufficient sleep directly shifts weight loss composition away from fat loss and toward lean tissue loss during caloric restriction. It suggests that adequate sleep is an essential component of dietary interventions aimed at reducing excess adiposity.
Limits
The sample size was very small (n = 10), the intervention duration was short (14 days per condition), and the study was conducted in a tightly controlled laboratory setting that may not fully reflect long-term, free-living conditions.
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