You have probably noticed that Americans are heavier than they were a few decades ago. Statistics confirm it: Nearly 70 percent of adults are now either overweight or obese, and the rate of obesity among children has tripled since 1980.
Many factors have been proposed, including sugar-sweetened beverages, lack of exercise and super-sized fast food portions. All have legitimate claims. Two other factors, sleep and psychosocial stress, apparently play a prominent role, as well.
On a personal level, you are probably aware of the subtle connections between sleep, stress and obesity. With a busy schedule, you find it impossible to get enough sleep. You’re constantly tired, and you overdose on coffee to keep going.
You ditch your exercise routine, and you don’t have time to sit down for a proper meal. All too often you reach for ready-to-eat comfort foods, such as a bag of chips from the vending machine. It’s a vicious circle, and there is more than anecdotal evidence to support it.
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Stress leads to increased release of cortisol, a hormone that inhibits the fat-burning gene in the liver. The result is weight gain, particularly abdominal or visceral fat.
In most persons, cortisol is at its highest level in the morning, then tapers off during the day until it reaches its lowest level just before bedtime. Chronic stress, however, keeps the cortisol level high throughout the day. Stress at bedtime may make it harder to get to sleep, and insomnia itself tends to raise the cortisol level even more.
Even without stress, many individuals today choose to sleep less. In 1960, large surveys found median sleep duration of 8.0 to 8.9 hours. By 2000, that number had fallen to 6.9 to 7.0 hours. Today, many Americans get by on only five to six hours a night.
Studies have found that individuals getting less than six hours sleep a night are about 50 percent more likely than others to be overweight or obese. But sleep quality, as well as duration, is important. Obese subjects with sleep complaints tended to score high on emotional stress profiles.
In addition to the effect of stress hormones, sleep loss also affects hormones that control appetite. Recent studies have found that sleep loss results in an increase in appetite that exceeds the extra calories demanded by wakefulness.
If you’re constantly concerned about your inability to control your weight, don’t lose sleep worrying about it. Instead, focus on getting more shut-eye.
Dr. David Williams is a family practice physician with Baptist Primary Care of Williamsburg.