If you’re cutting calories, exercising and still having a hard time losing weight then you may not be getting sufficient sleep, according to new research.
Paradoxically, dieters who slept an average of 8.5 hours per evening lost a greater proportion of body fat than lean body mass than those who slept just 5.5 hours. The study results were published in the October 5th issue of the Annals of Internal Medicine.
Previous research had suggested that decreased sleep time contributes to obesity. In this study, researchers at the University of Chicago wanted to test the effects of sleep loss on energy metabolism and weight loss.
The small study involved 10 middle-aged men and women, who had a body mass index between 25 and 32. The healthy but sedentary participants were put on a moderate calorie restricted diet (20 calories per kilogram of weight e.g., 1,363 calories for a 150 pound woman).
In a cross over study design, participants were assigned to either 8.5 hours of sleep for 14 days or 5.5 hours of sleep for 14 days. After a period of at least 3 months, each group was then switched to the opposite sleep pattern. To control sleep and monitor results, the research was performed in a sleep lab.
During the treatment, participants consumed a similar number of calories. Both sleep treatments contributed to approximately a 7 pound weight loss. However, more than half of the weight loss was fat in 8.5 hour group compared with a quarter in the 5.5 hour group (the longer sleepers lost 3.1 pounds of fat vs. 1.3 pounds in the 5.5 hour sleep group). Those who slept fewer hours lost more lean muscle mass (5.3 pounds) than those who slept longer (3.3 pounds).
Sleep restriction was also accompanied with increased hunger and higher levels of the hunger hormone ghrelin. Ghrelin has been shown to reduce energy expenditure, stimulate hunger and food intake and promote the retention of fat. The research showed that during times of caloric restriction, sleep deprivation amplifies the effects of ghrelin. At the same time, levels of leptin, the appetite suppressant hormone, decreased. Finally, resting metabolic rate was lower at the end of the 5.5 hour vs. 8.5 hour sleep period.
Study authors commented, “Our experimental data now indicate that sleep plays an important role in preservation of human fat-free body mass during periods of reduced caloric intake.”
The Bottom Line
It’s easy to recognize how sleep deprivation affects our energy level on a daily basis. But, I suspect that most people have no idea that getting less sleep each night may be contributing to their weight gain.
One of the most important ways to take care of your health is to get sufficient sleep. While that may mean 7.5 hours for you and 8.5 for someone else, the key is to figure what you need.
Making small changes in your lifestyle can help. A recent study indicated that Americans stay up late largely due to watching television. Start by making a cut-off time for television viewing. If you don’t have the discipline to stop the movie mid-way through, then don’t start watching.
Try to eat dinner at a reasonable time so that you have time to relax before going to bed. Limit your alcohol intake as drinking in excess disturbs sleep patterns. Don’t drink caffeine late in the day and try to get evening workouts done before 7:00PM. If pets are keeping you up at night, consider leaving them out of the bedroom so you can catch up on your sleep. In the weekday, try to get to bed around the same time so you can develop a natural sleep cycle.