As we reported yesterday, overweight people don’t eat enough food … of the right kind [3].
Similarly, while many may assume that overweight folks are lazy and are not motivated enough, the truth is that they may be too stressed out.
Specifically, stress increases appetite [4].
And it is well-documented that stress causes people to crave high-fat, high-carbohydrate junk foods which pack on belly fat. For example, the National Academy of Sciences reported [5] in 2003:
[The stress hormone cortisol] (GCs) … increase the salience of pleasurable or compulsive activities (ingesting sucrose, fat, and drugs, or wheel-running). This motivates ingestion of “comfort food.” … GCs act systemically to increase abdominal fat depots…. In stressed or depressed humans chronic stress induces either increased comfort food intake and body weight gain …. We propose that people eat comfort food in an attempt to reduce the activity in the chronic stress-response network with its attendant anxiety. These mechanisms, determined in rats, may explain some of the epidemic of obesity occurring in our society.
And while many would assume that overweight people are lazy and sleep too much, a lack of sleep actually increases obesity. For example, the Chicago Tribune reported [6] last year:
In 1960, Americans averaged 81/2 hours of sleep a night …
Study after study showing that a lack of good quality sleep—seven to nine hours of uninterrupted slumber—is making us fat. And it’s not just overworked adults who are gaining weight. Long-term studies are finding that sleep-deprived children also are piling on the pounds.
“You’re fighting against the tide to lose weight when you’re sleep-deprived,” said Dr. Amy Aronsky, medical director of The Center for Sleep Disorders in Portland, Ore., and a board certified sleep specialist. “Good sleep is as important as a good diet and exercise when it comes to weight loss.”
***
Studies have shown that when sleep is restricted, the hormone ghrelin increases and the hormone leptin decreases. Ghrelin tells our brain that we’re hungry, while leptin tells it we’ve eaten enough.
Average leptin levels decreased 18 percent when sleep was restricted to four hours per night over two nights, according to a study published in the journal Sleep Medicine by Dr. Eve Van Cauter, Average ghrelin levels increased 28 percent when sleep was restricted.
In other words, when we don’t get enough sleep we feel hungry, even if we’ve eaten enough.
In another Van Cauter study, healthy young volunteers showed signs of prediabetes when they were restricted to four hours of sleep for six nights in a row.
The stress hormone cortisol also surges when we’re sleep-deprived. When that happens, we crave high-fat, high-carbohydrate foods (“comfort foods”) to increase our serotonin levels to calm down, said Dr. Michael Breus, author of “The Sleep Doctor’s Diet Plan.”
Other studies consistently show that adults sleeping fewer than six hours a night increase their likelihood for becoming overweight or obese — even when exercising and eating right, Decker said. Among adults ages 32 to 49, those averaging five hours of sleep were twice as likely to be obese after nine years compared with those averaging seven hours.
The news for kids is just as alarming. A study of 8,234 children (starting at age 38 weeks) found that the odds of being obese by age 7 increased 50 percent for children averaging fewer than 101/2 hours of sleep. Another study found that 58 percent of obese kids averaged fewer than eight hours of sleep, while just 11 percent of non-obese kids averaged fewer than eight hours of sleep.
And see this [7], this [8] and this [9].
In addition, numerous studies show that melatonin reduces body weight and burns fat [10]. Our body produces melatonin when it is dark [11]. If we don’t get enough sleep, it means the light is on too much, and our body can’t produce enough melatonin.
Finally, reducing stress and getting enough sleep gives people extra energy to exercise. On other other hand, if people are stressed out and sleep deprived, they’ll be focused on just getting through the day, and will thus be less likely to exercise.
Of course, exercise is a powerful stress-reducer and cure for insomnia … so it goes both ways.