London: Dismissing the concept of 'fat but fit', a new study has found that the protective effects of high fitness against early death are reduced in obese men. 

Men of a normal weight, regardless of their fitness level, are at lower risk of death compared to obese individuals in the highest quarter of aerobic fitness, the findings showed. 

This study by researchers from Umea University in Sweden followed 1,317,713 men for a median average of 29 years to examine the association between aerobic fitness and death later in life, as well as how obesity affected these results.  

"The risk of early death was higher in fit obese individuals than in unfit normal-weight individuals," the study said. 

The aerobic fitness of the participants was tested by asking them to cycle till they had to stop due to fatigue. 

Men with top level of aerobic fitness had a 48 percent lower risk of death from any cause compared with those in the lowest levels.  

Stronger associations were observed for deaths related to suicide and abuse of alcohol and narcotics.  

Unexpectedly, the authors noted a strong association between low aerobic fitness and also deaths related to trauma.  

"We could only speculate, but genetic factors could have influenced these associations given that aerobic fitness is under strong genetic control," study co-author Peter Nordstrom said. 

However, the researchers found that the beneficial effect of high aerobic fitness was actually reduced with increased obesity, and in those with extreme obesity there was no significant effect at all. 

The study appeared in the International Journal of Epidemiology.