Catch Some Zzz’s to Lose Some Pounds
The average length of a night of sleep for an adult in the United States has decreased by 2 hours in the last 50 years. Increasing evidence reports the damaging effects of sleep deprivation and restriction on hormone release, cardiovascular function, and glucose regulation. Now, in fact, evidence shows that sleep loss undermines dietary efforts to lose weight, especially body fat.
Just the latest in a series of studies evaluating the effects of sleep on weight gain and obesity, a study from the University of Chicago, published in the Annals of Internal Medicine, found that insufficient sleep reduces the effectiveness of normal dietary interventions for weight loss. The study included 10 overweight adults who completed a 2-period 2-condition crossover study. The participants experienced 14 days of moderate caloric restriction and either 8.5 or 5.5 hours of nighttime sleep opportunity. The goal of the study was to measure loss of body fat and loss of fat-free body mass under each sleep condition. Hormone concentrations, energy expenditure, and hunger were also included in the analysis.
Overall, a short night’s sleep significantly decreased the amount of body fat lost by 55% (3 lbs vs. 1.3 lbs with 8.5 hours vs. 5.5 hours sleep, respectively). Also, the loss of fat-free body mass significantly increased by 60% with 5.5 hours sleep compared to 8.5 hours (5.3 lbs vs. 3.3 lbs). Further, participants with 5.5 hours sleep experienced increased hunger compared to the group with more sleep.
Other studies have demonstrated similar benefits of sleep, and correlated sleep restriction to the rise in obesity. Under conditions of sleep restriction (either shortened sleep or complete deprivation), subjects experienced reduced levels of leptin (the hormone that decreased appetite), increased levels of ghrelin (the hormone that simulates appetite), and increased hunger and appetite, particularly for calorie-dense, carbohydrate-rich foods. One study also concluded that sleep-restricted individuals consumed more calories from snacks than meals.
In addition to promoting weight gain and decreasing fat loss, chronic sleep loss induces excess glucocorticoid levels, which promotes memory loss and accelerates the aging process. Further, sleep loss contributes to the dysregulation of carbohydrate metabolism, specifically glucose, increasing the risk for the metabolic syndrome and type 2 diabetes.
Decreasing sleep to the minimum tolerable levels appears efficient and almost advantageous in today’s society. But, the long term effects of limiting the body’s ability to rest has significant metabolic and endocrine consequences, which may result in weight gain and obesity. Promoting healthy sleep schedules and habits for adults and children is a simple intervention that could result in large public health gains.
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