Experts say prior studies that examined the link between obesity and death are flawed because they rely on one-time measures of body mass index (BMI) that obscure the effects of weight change over time.
Studies that fail to distinguish between people who never exceeded normal weight and people of normal weight who were formerly overweight or obese are misleading because they neglect the enduring effects of past obesity. They also fail to account for the fact that weight loss is often associated with illness, the researchers say.
“The risks of obesity are obscured in prior research because most of the studies only incorporate information on weight at a single point in time.”