You may assume that if your weight is in the healthy range, you have a low risk of heart disease, diabetes, and other conditions linked to obesity. But new research suggests that waist size could play as important a role as body weight in determining how long you live. After examining a database of more than 100,000 men and women ages 50 and older participating in a cancer prevention study, researchers found that those with the largest waistlines had about twice the risk of dying over a nine-year period as those with the smallest waistlines. (Nearly 20 percent of the men and 10 percent of the women died over the duration of the study, mainly from heart disease, cancer, and respiratory conditions.)
What's especially troubling, though, is that even big-waisted folks who had a healthy body mass index—a measurement of weight to height—had a higher risk of dying. Every 4-inch increase in waist size was associated with a 25 percent greater risk of death, says Eric Jacobs, an epidemiologist at the American Cancer Society who led the study, published in the Archives of Internal Medicine . What is an ideal waist size? Less than 35 inches for men and 30 inches for women, according to the study. These measurements are considerably smaller than what the American Heart Association defines as optimal: below 35 inches for women and 40 inches for men.
Why is a big waist so dangerous? Previous research indicates that those who carry more fat around their abdomen also have higher amounts of fat around vital organs like the kidneys, liver, and pancreas; this so-called visceral fat is more "metabolically active" than fat that lies just below the skin and is thought to promote chronic inflammation, which has been linked to heart disease, diabetes, and certain cancers. Jacobs believes that action should be taken the moment you notice your pants getting too tight. "The take-home message is that it's important to watch your waist, not just your weight," he says, "and to start eating better and exercising more if you see your waist size starting to increase."
While eating fewer calories or burning off more through exercise can help reduce abdominal fat, a spate of recent studies also suggest that reducing stress and getting enough sleep—seven to eight hours a night for most people—can lower levels of stress hormones; that's a good thing since some of these hormones trigger the body to produce visceral fat. Researchers are also studying mindful eating, where you eat slowly and pay attention to the taste, smell, and texture of your food, to see whether the practice helps redistribute body fat from the waist to the hips.