Big Around the Middle = Big Health Risks

The link between obesity and health problems is well known. Current guidelines rely on body mass index (BMI), a ratio of height and weight, to determine if a person is obese; between 18 and 24.9 is considered normal, between 25 and 29.9 is considered overweight and over 30 is considered obese. However, the problem is that BMI does not distinguish between fat and muscle mass or how fat is distributed, which may make more of a difference to your health. Excess belly fat  has been linked to an increased risk of heart disease, high blood pressure, diabetes and stroke. Now, a new study has linked belly fat to a higher risk of early death, even for people who are not overweight.

In an attempt to better understand the role of belly fat in early death, researchers examined data on 359,387 European adults who were followed for about ten years as part of the European Prospective Investigation into Cancer and Nutrition (EPIC) health study. The participants, that were 51 years of age, on average, at the onset of the study, were divided into groups according to their BMI, waist circumference and waist-to-hips ratio. During the follow-up period, 14,723 of the participants died. BMI remained a reasonable predictor of health problems, with those with the highest reading more likely to die from cancer or cardiovascular disease. Those with the lowest risk of death were men with a BMI of 25.3 and women with a BMI of 24.3.

However, after adjusting for overweight and obesity, the hip/waist ratio and the waist measurement on its own were strong predictors of mortality. Men and women who weighed in the normal BMI range but had waists measuring more than 40 inches for men and 35 inches for women, had roughly twice the risk of early death as men and women with the smallest waists, less than 34 inches for men and 28 for women. Women in the normal BMI range with waists of 35 inches or more were 79 percent more likely to die than those with waists of 28 inches or less.

And the larger the waist circumference—the bigger the death risk. The researchers calculated that for each two-inch increase in waist size for patients with any given BMI score, the risk of death increased by 17 percent for men and by 13 percent for women. “Our study shows that accumulating excess fat around your middle can put your health at risk even if your weight is normal,” said the study’s lead author, Dr. Tobias Pischon, an epidemiologist and physician at the German Institute of Human Nutrition in Potsdam. “There aren’t many simple individual characteristics that can increase a person’s risk of premature death to this extent, independent of smoking and drinking.”

While the reason for the link is not entirely clear, recent research suggests that this visceral fat, which accumulates around the waist and around organs, is more metabolically active than subcutaneous fat, which lies just under the skin in other parts of the body. These adipose cells tend to produce inflammatory substances and trigger changes in hormones that can throw the body’s biochemical balance off kilter and contribute to the onset of various diseases.

Dr. Pischon said current treatment guidelines call for physicians to measure patients’ waists but usually only when their BMI indicates they are overweight. He said future research should consider whether treatment for weight problems should focus on preventing increases in waist size rather than holding down weight overall.

The study appears in the November 12 issue of The New England Journal of Medicine.