CHICAGO — If your pants are feeling a bit tight around the waistline, take note: Belly bulge can be deadly for older adults, even those who aren’t overweight or obese by other measures.

One of the largest studies to examine the dangers of abdominal fat suggests men and women with the biggest waistlines have twice the risk of dying over a decade compared to those with the smallest tummies.

Surprisingly, bigger waists carry a greater risk of death even for people whose weight is “normal” by the body mass index, or BMI, a standard measure based on weight and height.

“Even if you haven’t had a noticeable weight gain, if you notice your waist size increasing that’s an important sign,” said lead author Eric Jacobs of the American Cancer Society, which funded the study. “It’s time to eat better and start exercising more.”

Other research has linked waist size to dementia, heart disease, asthma and breast cancer.

Bulging bellies are a problem for most Americans older than 50. Men should have a relaxed waist no larger than 40 inches at the navel. For women, the limit is 35 inches.