The "fat but fit" concept has recently been debunked with a new study showing that obese people who engage in high fitness level are still more likely to die compared to normal-weight individuals who don't exercise.

The study was published online last Sunday in the International Journal of Epidemiology and was conducted by researchers in Sweden.

Several studies have pointed out that obese people have less chances of developing serious illness if only they engage in physical activities regularly. In addition, studies about fitness and obesity and how it is associated with premature death only involved the older populations. But this latest study aimed to find out if the effects are the same for the younger population.

To come up with a conclusion, the investigators tracked more than 1.3 million men with an average age of 18 for about 29 years. The participants' physical fitness was assessed by requiring them to cycle until they get exhausted.

After follow-up, men in the highest fifth of fitness level were found to have a 48 percent lower risk of premature death from any cause compared to those in the lowest fifth. Surprisingly, researchers found that obese men who exercise regularly are no different — they are still more likely to die compared to slim or normal-weight men.

Study co-author Prof. Peter Nordstrom of Umea University in Sweden highlighted that the findings "suggest low BMI (body mass index) early in life is more important than high physical fitness" when it comes to lowering the risk of premature death.

Apart from busting the "fat but fit" myth, the study also found that the health benefits of regular exercise were reduced in obese people. Further, the benefits were not seen among those who are extremely obese.

The researchers concluded in their study that low aerobic fitness in the younger population may increase the risk of premature death, but the risk is higher for obese individuals who are fit than normal-weight individuals who are unfit.