Sleep plays an important role in weight management. People who sleep enough have lower body mass indexes (BMI) than people who don’t. Recent research data suggests that sleep deprivation can cause weight gain. Women who got only 4 hours of sleep at night ate 329 additional calories the next day than they did after they slept nine hours. (Men ate 263 calories more.) In another study, 11 volunteers spent 14 days at a sleep center on two occasions. During one period, they slept 5.5 hours a night, and during the other, they slept 8.5 hours. When the subjects were sleep-deprived, they increased their nighttime snacking and were more likely to choose high-carbohydrate snacks.
The biggest revelation about the connection between sleep and weight loss, and the biggest challenge for you if you’re not getting at least seven solid hours of sleep each night, is that sleeping too little impacts your hormone levels in ways that can undermine the efforts of even the most determined dieter. There are several hormones that link sleep with weight loss. Leptin and ghrelin are two hormones that play an important role in stimulating and suppressing your appetite. Ghrelin’s job is to boost your appetite, increase fat production, and make your body grow, which are undesirable effects once you’ve passed your teenage years. It’s easy to figure out why this hormone is the last thing a dieter needs to have circulating in excess. On the other hand, leptin is responsible for suppressing hunger. Leptin is the hormone that says, “I’m full; put the fork down.” Lack of sleep lowers the levels of leptin in your blood and heightens the levels of ghrelin, which results in an increase of appetite. The reverse is also true: getting enough sleep decreases hunger and will therefore help you lose weight. So after even one night of too little sleep, leptin and ghrelin become dietary gremlins bent on diet-wrecking mischief. The lower leptin levels mean that you still feel hungry after you eat. And ghrelin, for its part, magnifies the problem by stimulating your appetite, setting the stage for a day of high simple carbohydrate, high-calorie feasting after a restless night. Another important hormone affected by sleep is growth hormone. During sleep, your pituitary gland secretes more growth hormone than during your waking hours. Growth hormones stimulate cell regeneration, reproduction and growth. These hormones are also known to aid you in building muscles. This is why higher levels of growth hormones results in a heightened metabolism. With a higher metabolism, you burn energy faster, which will lead to easier weight loss. Finally, cortisol is another important hormone affected by sleep. Getting eight hours of sleep at night helps you lower the cortisol levels in your blood, while lack of sleep raises your cortisol levels. High levels of cortisol lead to a lower metabolism and cause you to crave simple carbs. High cortisol levels lead to elevated blood sugar levels, increased insulin levels, and finally obesity. (Stress also leads to increased cortisol levels.) If you are trying to lose weight, you want to make sure that you have low cortisol levels in your blood. Low cortisol levels lead to lower insulin levels, which help you to lose weight. Getting enough sleep helps you do just that.
Overall, sleep is a crucial factor in losing weight. Sleep suppresses your appetite and raises your metabolism, while allowing your body to rest and recover. So aside from eating a nutritious, high fiber diet and participating in regular aerobic exercise, you should also make sure that you get your full seven to eight hours of sleep every night to help you optimize your hormone levels and promote weight loss. Do not skimp. The next post will discuss several ways to help you sleep.