Insufficient Sleep Undermines Dietary Efforts to Reduce Adiposity
I thought that this particular study, albeit small, was of interest. Two dieting groups ended up losing the same amount of weight over a two week period. One group slept for 8 hours and the other group slept for 5.50 hours. The group that slept for 5.50 hours, lost significantly less fat and increased their loss of fat free mass ( muscle ). We have all heard how important sleep is with regard to health and training and this small study seems to back this up. Problem is, and I don't know about you, but when I am dieting, I find that I need less sleep. Another example of Sod's Law, maybe ?
Annals of Internal Medicine
October 5, 2010 vol. 153 no. 7 435-441
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.
