The statistics are alarming: About 65% of Americans are now overweight or obese, according to the Centers for Disease Control and Prevention. The number of obese adults (those with a Body Mass Index of 30 or more) jumped from 15% in 1980 to 27% in 1999. More than 15% of children from 6 to 19 years were overweight in 2000, which is three times higher than in 1980.
Why are we as a nation getting fatter? "A hundred and fifty years ago, a sedentary lifestyle was considered to be that of a farmer's wife," says Richard Simon, MD, a sleep specialist in Walla Walla, WA. "Our levels of physical activity have plummeted, along with our caloric expenditure, yet our caloric intake has not declined. When caloric expenditure declines and caloric intake does not decline, weight gain occurs.
"We're also getting less sleep than we used to," Simon adds. "Add all of those features together, and we have a perfect model for obesity."
This epidemic of obesity is particularly serious for children. The CDC says that 1 in 3 American children born in 2000 will develop diabetes, and children under 10 years of age are already developing type 2 diabetes, which is primarily seen in adults—usually not until past the age of 40.
Uncontrolled diabetes can lead to hypertension and increased risk of heart attack. It also damages the eyes, kidneys and other vital organs. The earlier one develops the disease, the greater the potential for long-term damage, especially if the diabetes isn't diagnosed and brought under treatment.
The problem of obesity in children is a major concern for another reason: the increased incidence of sleep apnea. A 20-year review of obesity-associated diseases among children aged 6 to 17 conducted by the CDC found a significant increase in hospital discharges for a number of obesity-related medical conditions. Discharges for sleep apnea increased 436%.
The problem is no less serious for adults. An estimated 18 million Americans have sleep apnea, which is often associated with people who are overweight. "As the person gains weight, especially in the trunk and neck area, the risk of sleep-disordered breathing increases due to compromised respiratory function," say Margaret Moline, PhD, and Lauren Broch, PhD, two sleep specialists at New York Weill Cornell Medical Center.
"If a person is overweight and suffering from sleep-disordered breathing, he/she may not be as motivated to exercise or to diet. When apnea leads to daytime sleepiness, it may be that much harder to begin or sustain an exercise program, which has been shown to help people begin or maintain weight loss." Not only does obesity contribute to sleep problems such as sleep apnea, but sleep problems can also contribute to obesity. A 1999 study by scientists at the University of Chicago found that building up a sleep debt over a matter of days can impair metabolism and disrupt hormone levels. After restricting 11 healthy young adults to four hours' sleep for six nights, researchers found their ability to process glucose (sugar) in the blood had declined—in some cases to the level of diabetics.
A follow-up study tested healthy men and women with an average body mass index; half were normal sleepers, the other half averaged 6 1/2 hours or less. Glucose tolerance tests showed that the short sleepers were experiencing hormonal changes that could affect their future body weight and impair their long-term health. To keep their blood sugar levels normal, the short sleepers needed to make 30% more insulin than the normal sleepers. Both studies were led by Eve Van Cauter, PhD, who termed sleep deprivation "the royal route to obesity. Despite not yet being overweight," she said, "these young adults had profiles that predisposed them to putting on weight."
"Dr. Van Cauter's research shows that people who don't sleep adequately have physiologic abnormalities that may increase appetite and calorie intake," notes Simon. "The level of leptin [an appetite stimulating hormone] falls in subjects who are sleep deprived, which promotes appetite. It suggests that at least one factor in obesity can be sleep deprivation. Poor sleep and sleep deprivation may increase appetite. Because the psychological manifestations of fatigue, sleep and hunger are similar, as adults, we sometimes confuse them—we tend to eat when we’re actually sleepy, because we think fatigue is a sign of hunger."
Sometimes the best way to treat obesity can be to treat an underlying sleep problem.
"Successful treatment of sleep apnea, usually with nasal continuous positive airway pressure (CPAP), may reduce sleepiness and then motivate patients to effectively lose weight, which will in turn help the obesity and the sleep apnea," according to Moline and Broch. Most experts say as little as a 10% decrease in weight can lead to significant clinical improvement in the severity of sleep apnea. However, in the more severe cases of apnea, CPAP is a necessary first step to better sleep and feeling motivated to embark on a weight loss program.
So if you are overweight or obese and sleep poorly or feel tired during the day, what should you do?
"First, you should talk to your primary care clinician about a referral to a sleep center so that the nature of the disorder can be fully addressed," suggest Moline and Broch. "Patients should also talk to their bed partners who are likely hearing loud snoring and apnea. Bed partners can be encouraged to accompany the patient tothe sleep center, as appropriate. "After determining the diagnosis, then the sleep issues can be incorporated into a weight loss plan. It is especially important for obese patients who are contemplating gastric surgery to discuss any snoring/apnea problems with their doctors beforehand, since the use of CPAP both before and after the surgery can be very important and in fact, life-saving."
They also suggest a follow-up sleep study after the patient has lost 10% of body weight in order to determine further treatment.
Sleep experts say there are a number of things you can do to lose weight and improve your sleep:
Just weighing yourself on a scale isn't always the answer, since muscle weighs more than fat. To find out what your body mass index (BMI) is, go to the National Heart, Lung, and Blood Institute's Web page.
NSF's 2003 Sleep in America poll shows that: