A study in the Annals of Internal Medicine suggests that when you’re trying to lose weight, if you sleep enough, you lose body fat — if you’re sleep deprived you just lose muscle.
The population in the study was small (10 overweight or obese adults participated), but it was highly controlled, so the results are still interesting. Most large scale studies rely on self-report and it’s hard to account for all the variables in a person’s life. In this case the subjects were in a controlled environment for four weeks, where their eating, sleeping, and exercise patterns were closely monitored.
How much sleep did the adults need to lose body fat?
During one phase of the study, they slept 8.5 hours a night — during another, only 5.5. Even though their calorie consumption stayed constant and both groups lost a steady 6.6 lbs each two weeks, when the subjects got 8.5 hours of sleep they lost 3.1 lbs of body fat, but when they were sleep deprived, only 1.3 lbs of the weight loss came from body fat, the rest was lean body mass (muscle). It’s a self-perpetuating cycle, because losing muscle slows metabolism.
We saw earlier this year that babies and teens are more apt to gain weight when they sleep less. Mom and dad can now be included in this.
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