Fitness vs Fatness: Which Is More Important to All-Cause Mortality?

Risk of early death is higher in individuals who are aerobically fit but obese than in those who are unfit and of normal weight, according to a recent study.

In order to investigate the relationship between fitness in late adolescence and early death, researchers examined data from 1,317,713 Swedish men (mean age 18 years) collected between 1969 and 1996. Using a cycling test, researchers assessed the participants aerobic fitness, and tracked all-cause and specific causes of death using national registers.
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During a mean follow-up of 29 years, 44,301 individuals died. Those in the highest tier of aerobic fitness were shown to be at the lowest risk of death, compared to those in the lowest tier who were at the highest risk for death, particularly those related to alcohol and narcotics abuse.

After adjusting for weight, researchers found that fitness was associated with reduced risk of death in normal-weight and overweight individuals, but benefits were reduced in obese individuals. Whereas, normal-weight but unfit individuals had 30% lower risk of death than fit obese individuals.

“Low aerobic fitness in late adolescence is associated with an increased risk of early death. Furthermore, the risk of early death was higher in fit obese individuals than in unfit normal-weight individuals,” they concluded.

—Michael Potts

Reference:

Hogstrom G, Nordstrom A, Nordstrom P. Aerobic fitness in late adolescence and the risk of early death: a prospective cohort study of 1.3 million Swedish men. Int. J. Epidemiol. December 20, 2015 [epub ahead of print]. doi: 10.1093/ije/dyv321.