Adequate Sleep Promotes a Lean Body

Previous studies have shown that inadequate sleep has adverse effects on energy intake and expenditure.  Plamen D. Penev, MD, from the University of Chicago (Illinois, USA), and colleagues enrolled 3 overweight, nonsmoking women and 7 overweight, nonsmoking men, average age 41 years, in a two-week long study involving moderate caloric restriction with 8.5 or 5.5 hours of nighttime sleep opportunity. The team monitored for changes including loss of fat and fat-free body mass, energy expenditure, hunger, and 24-hour metabolic hormone concentrations. Subjects who slept 8.5 hours nightly burned more fat than those who slept just 5.5 hours, with the latter group burning more lean muscle mass, experiencing hunger, and expending less energy as a result of the lack of sleep. The subjects who slept for more than 8 hours lost an average of 1.4 kg, as compared to 0.4 kg of fat loss in the sleep deprivation group. Explaining that: “The amount of human sleep contributes to the maintenance of fat-free body mass at times of decreased energy intake,” the researchers observe that: “Lack of sufficient sleep may compromise the efficacy of typical dietary interventions for weight loss and related metabolic risk reduction.”