Obesity and diabetes

According to the Centers for Disease Control and Prevention, about 65 percent of Americans now are overweight or obese. The same tendency is observed in all western countries. Why are the nations getting fatter? Most experts attribute it to our sedentary lifestyle combined with our caloric intake. But we're also getting less sleep than we used to, a factor whose role in obesity is just coming to light. Researchers have measured the impact of sleep deprivation on certain hormones that affect the tendency toward obesity. For example, decreased slow wave sleep in young men is associated with decreased production in growth hormone. Because growth hormone plays an important role during adulthood in controlling the body's proportions of fat and muscle, having less of it as men age increases the tendency toward becoming overweight and having a paunch in middle age. Other short-term studies have found a correlation between inadequate sleep and insufficient levels of the hormone leptin, which regulates carbohydrate metabolism.

Low levels of leptin causes the body to crave carbohydrates regardless of the amount of calories consumed. The growing problem of obesity is also linked to diabetes. A 1999 study at the University of Chicago found that a sleep debt accumulated over a matter of days can impair sugar metabolism and disrupt hormone levels. After 11 healthy young adults were allowed only a restricted amount of sleep (four hours) for several nights, their ability to process blood glucose had declined, in some cases to apre-diabetic state, prompting their bodies to produce more insulin.