New Study Questions “Obesity Paradox”
A weight history that includes periods of overweight or obesity is associated with a higher risk of all-cause and specific-cause mortality compared with maintained normal weight, according to a recent study.
For their study, researchers assessed the relationship between 16-year weight history and mortality using data from 3 prospective cohort studies: the Nurses’ Health Study I and II and the Health Professionals Follow-Up Study. The researchers defined overweight as 25 kg/m2 to 29.9 kg/m2, obese I as 30 kg/m2 to 34.9 kg/m2, and obese II as 35 kg/m2 or greater.
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Over a mean 12.3 years of follow-up, 32,571 deaths occurred among the 225,072 participants.
Having a maximum BMI in the overweight, obese I, and obese II categories was associated with increased risk for all-cause mortality (hazard ratios: 1.06, 1.24, and 1.73, respectively), as well as death related to cardiovascular disease and coronary heart disease.
Conversely, a significant inverse association between overweight and mortality was found when BMI was defined as a single baseline measurement.
“The paradoxical association between overweight and mortality is reversed in analyses incorporating weight history. Maximum BMI may be a useful metric to minimize reverse causation bias associated with a single baseline BMI assessment,” the researchers concluded.
—Melissa Weiss
Reference:
Yu E, Ley SH, Manson JE, et al. Weight history and all-cause and cause-specific mortality in three prospective cohort studies [published online ahead of print April 4, 2017]. Ann Intern Med. doi: 10.7326/M16-1390.