Insufficient sleep undermines dietary efforts to reduce adiposity.

BACKGROUND

Sleep loss can modify energy intake and expenditure.

OBJECTIVE

To determine whether sleep restriction attenuates the effect of a reduced-calorie diet on excess adiposity.

DESIGN

Randomized, 2-period, 2-condition crossover study.

SETTING

University clinical research center and sleep laboratory.

PATIENTS

10 overweight nonsmoking adults (3 women and 7 men) with a mean age of 41 years (SD, 5) and a mean body mass index of 27.4 kg/m² (SD, 2.0).

INTERVENTION

14 days of moderate caloric restriction with 8.5 or 5.5 hours of nighttime sleep opportunity.

MEASUREMENTS

The primary measure was loss of fat and fat-free body mass. Secondary measures were changes in substrate utilization, energy expenditure, hunger, and 24-hour metabolic hormone concentrations.

RESULTS

Sleep curtailment decreased the proportion of weight lost as fat by 55% (1.4 vs. 0.6 kg with 8.5 vs. 5.5 hours of sleep opportunity, respectively; P = 0.043) and increased the loss of fat-free body mass by 60% (1.5 vs. 2.4 kg; P = 0.002). This was accompanied by markers of enhanced neuroendocrine adaptation to caloric restriction, increased hunger, and a shift in relative substrate utilization toward oxidation of less fat.

LIMITATION

The nature of the study limited its duration and sample size.

CONCLUSION

The amount of human sleep contributes to the maintenance of fat-free body mass at times of decreased energy intake. Lack of sufficient sleep may compromise the efficacy of typical dietary interventions for weight loss and related metabolic risk reduction.

PRIMARY FUNDING SOURCE

National Institutes of Health.