The notion that being "fat but fit" is OK has been debunked by a new study which found that the protective effects of being fit are highly reduced in obese people.
Swedish researchers followed 1.3 million men for nearly 30 years to see if aerobic fitness was enough to stave off early death in those who were overweight.
The study found that men of a normal weight -- regardless of their fitness level -- were at a lower risk of death compared to those who were highly fit but obese.
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 researchers said.
Surprisingly, the researchers found a strong association between low aerobic fitness and 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," said study co-author Peter Nordström.
The study is being published today in the International Journal of Epidemiology.