“Many people today are overweight or obese, and diet-induced weight loss is a widely used strategy to reduce the health risks associated with excess adiposity,” write Arlet V.Nedeltcheva, MD, from the University of Chicago, Illinois, and colleagues. “The neuroendocrine changes associated with sleep curtailment in the presence of caloric restriction, however, suggest that lack of sufficient sleep may compromise the efficacy of commonly used dietary interventions in such persons.”
In this study, the authors examined whether “recurrent bedtime restriction” affected the amount of weight people lost when dieting, increased their hunger, and affected their leptin and ghrelin serum concentrations. They also examined changes in circulating cortisol, epinephrine, norepinephrine, thyroid, and growth hormone concentrations due to sleep loss.
They randomized 10 overweight, nonsmoking adults (3 women, 7 men) whose mean age was 41 years and whose body mass index ranged from 25 to 32 kg/m2 to 14 days of dieting and 8.5 hours of nighttime sleep and then to a similar period of dieting and 5.5 hours of nighttime sleep.
The study took place in a sleep laboratory, and subjects were sedentary and spent their waking hours doing home office–type work or leisure activities.
The study found that the reduced sleep decreased the proportion of weight lost as fat by 55%. Subjects who slept 8.5 hours per night lost a mean of 1.4 kg, and those who slept 5.5 hours per night lost a mean of 0.6 kg (P = .043).
Also, sleep curtailment increased the loss of fat-free body mass by 60%. Subjects who slept 8.5 hours per night lost a mean of 1.5 kg, whereas those who slept 5.5 hours lost a mean of 2.4 kg (P = .002).
The study also found that less sleep time resulted in increased hunger and higher fasting and postprandial and 24-hour acylated ghrelin concentrations but lower resting metabolic rate and 24-hour plasma epinephrine concentrations. Leptin concentrations decreased in parallel with the loss of weight and adiposity without a significant independent effect of sleep loss (P = .001).
Limitations of the study are its duration and small sample size, they note.
“These results highlight the importance of adequate sleep for maintenance of fat-free body mass when dieting to lose weight,” senior study author Plamen Penev, MD, PhD, University of Chicago, said in a statement.
“Among other hormonal effects, we found that sleep restriction caused an increase in ghrelin levels in the blood. Ghrelin is a hormone that has been shown to reduce energy expenditure, stimulate hunger and food intake, promote retention of fat, and increase glucose production in the body. This could explain why sleep-deprived participants also reported feeling hungrier during the study,” he continued.
In an accompanying editorial, Shahrad Taheri, MBBS, PhD, University of Birmingham, United Kingdom, and Emmanuel Mignot, MD, PhD, Stanford Sleep Medicine Center, Redwood City, California, agree that adequate sleep might be an important factor in successful weight loss and suggest sleep might be part of a lifestyle package that has traditionally focused on diet and exercise.
However, they note that the study includes only 10 healthy individuals and that its results may not generalize to other people with comorbid conditions. Also, sleep laboratory studies are not applicable to real life, where many other factors can influence a person’s ability to stay on a diet.
Dr. Taheri and Dr. Mignot conclude that replicating the findings from this study in clinical trials is “a critical next step in addressing important questions about sleep and body weight.”