The BBC report a study on fitness in obese people: People can be fat yet fit, research suggests in which they say:
People can be obese yet physically healthy and fit and at no greater risk of heart disease or cancer than normal weight people, say researchers.
A quick look at the abstract to the paper (I haven’t seen the full text as this is not an open journal) shows that they considered people above and below 30% (women) or 25% (men) body fat mark as being obese or ‘normal’. Note that there is no ‘overweight’. The paper concludes that fit obese people are at no greater risk than fit normal people provided they didn’t have any other risk factors (hypertension etc). Note also that this is not a longitudinal study. They are just showing that some obese people are fit not that some obese people actual live as long as non-obese people all other things being equal.
The non-obese people in the study might actually have been quite fat. A quick look at the wikipedia page on body fat percentage shows that normal covers a very large range of fatness. As normal in the USA and UK is overweight according to BMI then the control group in this study were probably fat on average.
Basically the study shows that one of the risk factors for a disease can be removed without effecting outcomes too much theoretically. The key is “normal weight people” in the sentence above. They didn’t consider people who weighed what they “should” weigh. Nor did they consider that if you are obese (of even fat) the chances that you will develop one of the other risk factors soon is increased.
Conclusion: Wooly study shows not very much. News item written to comfort the fat. BBC doesn’t permit people to comment on the story.