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Overweight, obesity increase risk for early death
In nearly all regions of the world, both overweight and obesity are associated with higher all-cause mortality in otherwise healthy, nonsmoking adults, with greater risk observed in men vs. women, according to new findings from a collaborative study.
“On average, overweight people lose about 1 year of life expectancy, and moderately obese people lose about 3 years of life expectancy,” Emanuele Di Angelantonio, MD, PhD, lecturer in the cardiovascular epidemiology unit at the University of Cambridge, United Kingdom, said in a press release. “We also found that men who were obese were at much higher risk for premature death than obese women. This is consistent with previous observations that obese men have greater insulin resistance, liver fat levels and diabetes risk than women.”
Di Angelantonio, a member of the Global BMI Mortality Collaboration that wrote the study, and colleagues analyzed data from 3,951,455 nonsmoking adults without specific chronic diseases at baseline who survived 5 years (189 studies). Within the cohort, 385,879 died.
Researchers found that mortality was lowest in the BMI range of 20 kg/m² to less than 25 kg/m² (HR = 1) and gradually increased in overweight and obese ranges above that. The HR in the BMI range of 25 kg/m² to 27.5 kg/m² was 1.07 (95% CI, 1.07-1.08), increasing to 1.2 in the BMI range of 27.5 kg/m² to 30 kg/m² (95% CI, 1.18-1.22), 1.45 in the BMI range of 30 kg/m² to 35 kg/m² (95% CI, 1.41-1.48), 1.94 for the BMI range of 35 kg/m² to 40 kg/m² (95% CI, 1.87-2.01) and 2.76 for the BMI range of 40 kg/m² to 60 kg/m² (95% CI, 2.6-2.92).
For BMI more than 25 kg/m², mortality increased approximately log-linearly with BMI, according to researchers, with an HR of 1.39 per 5 kg/m² units higher BMI (95% CI, 1.34-1.43) in Europe, 1.29 (95% CI, 1.26-1.32) in North America, 1.39 (95% CI, 1.34-1.44) in East Asia and 1.31 (95% CI, 1.27-1.35) in Australia and New Zealand.
The HR decreased with age from 1.52 for age 35 to 49 years at baseline to 1.21 for age 70 to 89 years at baseline (P < .0001 for trend). The HR was also higher for men (HR = 1.51, 95% CI, 1.46-1.56) vs. women (HR = 1.3, 95% CI, 1.26-1.33).
For each major cause of death, researchers found that BMI was nonlinearly associated with morality in each major region studied; more than 25 kg/m², BMI was related to coronary heart disease, stroke and respiratory disease mortality.
Researchers also estimated the population-attributable fraction for mortality due to overweight and obesity. Assuming the associations between high BMI and mortality are largely causal, if those with overweight or obesity had WHO-defined normal levels of BMI, the proportion of premature deaths that would be avoided would be about one in seven in Europe and one in five in North America, the researchers said.
“Obesity is second only to smoking as a cause of premature death in Europe and North America,” Richard Peto, FRS, professor of medical statistics and epidemiology at the University of Oxford, United Kingdom, said in a press release.
The researchers also noted that BMI does not assess fat distribution in different parts of the body, muscle mass or obesity-related metabolic factors, such as blood glucose or cholesterol. – by Regina Schaffer
Disclosure: The study was funded by British Heart Foundation, National Institute of Health Research, U.S. NIH and UK Medical Research Council. Di Angelantonio reports receiving funding from British Heart Foundation, European Commission Framework Programme, National Institute of Health Research, NHS Blood and Transplant, and UK Medical Research Council during the study; and personal fees from Elsevier (France). Peto reports no relevant financial closures. Please see the full study for a list of the other authors’ relevant financial disclosures.
“Obesity is second only to smoking as a cause of premature death in Europe and North America.”