How long have we been hearing that being overweight was the ticket to an early grave? Well, it turns out it's not necessarily so, as long as we're talking about overweight as opposed to obesity, a large analysis suggests.
In the latest word on the subject, an analysis of nearly 100 studies that included approximately 3 million adults found that being overweight carried a lower risk of death than normal weight or being obese, according to a study in the January 2 issue of JAMA.
The researchers said their findings are consistent with observations of lower mortality among overweight and moderately obese patients.
“Possible explanations have included earlier presentation of heavier patients, greater likelihood of receiving optimal medical treatment, cardioprotective metabolic effects of increased body fat, and benefits of higher metabolic reserves.”
It's important to note two things:
- The study looked at all causes of mortality, not just heart disease, stroke and cancer, which are sometimes associated with obesity and overweight.
- The study makes a sharp distinction between overweight and obese, based on a standardized measure called body mass index (BMI), a measure of body fat based on height and weight that applies to adult men and women. You can calculate your BMI here.
The researchers found a 6 percent lower risk of death for overweight; a 18 percent higher risk of death for obesity (all grades); a 5 percent lower risk of death for grade 1 obesity; and a 29 percent increased risk of death for grades 2 and 3 obesity.
The study was conducted by Katherine M. Flegal, Ph.D., of the National Center for Health Statistics, Centers for Disease Control and Prevention, Hyattsville, Md., and colleagues. They identified 97 studies that met inclusion criteria, which provided a combined sample size of more than 2.88 million individuals and more than 270,000 deaths.
“Not all patients classified as being overweight or having grade 1 obesity, particularly those with chronic diseases, can be assumed to require weight loss treatment. Establishing BMI is only the first step toward a more comprehensive risk evaluation,” an accompanying editorial noted.
“The presence of a wasting disease, heart disease, diabetes, renal dialysis, or older age are all associated with an inverse relationship between BMI and mortality rate, an observation termed the obesity paradox or reverse epidemiology," said Steven B. Heymsfield, M.D., and William T. Cefalu, M.D., of the Pennington Biomedical Research Center, Baton Rouge, La.
"The optimal BMI linked with lowest mortality in patients with chronic disease may be within the overweight and obesity range. Even in the absence of chronic disease, small excess amounts of adipose tissue may provide needed energy reserves during acute catabolic illnesses, have beneficial mechanical effects with some types of traumatic injuries, and convey other salutary effects that need to be investigated in light of the studies."