A new report on nearly three million people found that people whose BMI ranked them as overweight had less risk of dying than people of normal weight. Obese people had the greater mortality risk overall, but those at the lowest obesity level, a BMI of 30 to 34.9, were not more likely to die than normal-weight people.
The report isn’t the first to suggest this relationship between BMI and mortality, but it’s by far the largest and most carefully done. Experts suggest that overweight people need not panic unless they have other indicators of poor health. Depending of where fat is located on the body, it could be protective or even nutritional for older or sicker people. But piling on the pounds and becoming more than slightly obese remains dangerous to health.
The report, which will be published in The Journal of the American Medical Association on January 2, suggests that BMI, a ratio of height to weight, shouldn’t be the only indicator of a healthy weight.
BMI is imperfect to measure the risk of mortality, and like other factors like blood pressure, cholesterol and blood sugar must be considered. For overweight people, if cholesterol is in the abnormal range, then the weight is affecting them. If that and other indicators are normal, there’s no reason to go on a crash diet.
The study did show that the two highest obesity categories, of BMI 35 and higher, are at high risk. The type of fat inside your belly is bad, whereas non-belly fat underneath your skin and in your thigh and butt area, isn’t necessarily bad.
People 65 years and older had no greater risk even at high obesity levels. Even if being overweight doesn’t increase the risk of patients dying, it does increase their risk of having diabetes or other conditions.
Reference: “Association of All-Cause Mortality With Overweight and Obesity Using Standard Body Mass Index Categories – A Systematic Review and Meta-analysis” by Katherine M. Flegal, PhD; Brian K. Kit, MD; Heather Orpana, PhD and Barry I. Graubard, PhD, 2 January 2013, JAMA.