Because it is. If the results were true, it would have an impact on almost every study concerning exercise, and it would have been old news. But that's clearly not the case. Furthermore it states that for some people it's impossible to lose fat, which means either their bodies violate thermodynamics, or they have some kind of fucked up condition preventing their body from using stored fat as energy. And I have a very hard time believing that natural selection would allow 10% of the population to have such a condition.
And that's if it's even a "valid" study. Newspapers will report on things they find in other papers, or online, etc., and next thing you know you have "the onion" being used as a reliable source, or wikipedia validating a Journalist, who is then cited as a source for that bit of information, or a tabloid in Hong Kong creating leading to all kinds of misinformation in other newspapers around the world. And all of the above are true cases, that I know of off the top of my head. The point is that newspapers have dodgy fact checking at best, and that we should all check our facts and consider the source of any information.