Cutting back on sleep reduces the benefits of dieting, according to a study published in the Annals of Internal Medicine.
When dieters in the study got a full night's sleep, they lost the same amount of weight as when they slept less. When dieters got adequate sleep, however, more than half of the weight they lost was fat. When they cut back on their sleep, only one-fourth of their weight loss came from fat.
They also felt hungrier. When sleep was restricted, dieters produced higher levels of ghrelin, a hormone that triggers hunger and reduces energy expenditure.
The study, performed at the University of Chicago's General Clinical Resource Center, followed 10 overweight but healthy volunteers aged 35 to 49 with a body mass index ranging from 25, considered overweight, to 32, considered obese.
Participants were placed on an individualized, balanced diet, with calories restricted to 90 percent of what each person needed to maintain his or her weight without exercise.
Each participant was studied twice: once for 14 days in the laboratory with an 8.5-hour period set aside for sleep, and once for 14 days with only 5.5 hours for sleep. They spent their waking hours engaged in home- or office-like work or leisure activities.
During the two-week, 8.5-hours-in-bed phase, volunteers slept an average of 7 hours and 25 minutes each night. In the 5.5-hour phase, they slept 5 hours and 14 minutes, or more than two hours less. The number of calories they consumed, about 1,450 per day, was kept the same.
The volunteers lost an average of 6.6 pounds during each 14-day session. During weeks with adequate sleep, they lost 3.1 pounds of fat and 3.3 pounds of fat-free body mass, mostly protein.
During the short-sleep weeks, participants lost only 1.3 pounds of fat.
The message for people trying to lose weight is clear, say researchers. One should not ignore the way they sleep when going on a diet. Obtaining adequate sleep may enhance the beneficial effects of a diet, while not getting enough sleep could defeat the desired effects.
For optimal health, adults need 7 to 9 hours of sleep each night; children and teenagers need 9 to 10.
All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.