Heart Risk of Obesity Greater Than Thought

Study Also Shows Health Risks of Being Underweight May Have Been Overstated

Medically Reviewed by Brunilda Nazario, MD on December 28, 2009

Dec. 28, 2009 -- The link between obesity and death from heart disease may be even worse than previously thought, but health problems associated with being underweight may have been exaggerated, a new study shows.

Previous studies have shown that a higher than normal body mass index (BMI), a barometer of unhealthy weight levels, is associated with higher rates of death from cardiovascular disease. Studies also have shown a link between being underweight, or having a low BMI, with increased mortality from such problems as respiratory disease and lung cancer.

But scientists at the University of Bristol in the U.K. and the Karolinska Institute in Sweden now say they've found that the risks of death from cardiovascular disease for people who are overweight or obese may have been understated, and the adverse consequences of having a low BMI have been overstated.

The study appears in the journal BMJ.

The researchers examined data on more than a million pairs of Swedes, studying mother-son and father-son pairs over age 50. In the study, offspring BMI was used as an indicator of parental BMI.

The researchers' analysis of the data shows a strong association between high offspring BMI and parental mortality from cardiovascular disease, diabetes, and some cancers.

The data also suggested no association between a low BMI and an increased risk of respiratory disease or death from lung cancer.

This is important, they write, because the prevalence of obesity and average body mass index have been rising rapidly in industrialized countries.

"Academic and governmental agencies predict that these increases will generate adverse trends in the incidence of, and mortality from, diseases considered to be related to obesity, such as diabetes, coronary heart disease, stroke, and many cancers," the researchers write.

"These conclusions have important implications for public health practice because they suggest that reducing population levels of overweight and obesity or preventing their rise will have a considerable benefit to population health," the researchers write. "Suggestions to the contrary are probably misguided."