You can't have it both ways

Take a look at the third "weight loss myth" on this list. It says that research (in other words, actual data) shows that there's no difference in BMI for students with and without regular PE classes. In other words, there is no evidence that PE classes help reduce childhood obesity.

Then it says "Anything that gets children moving is a step in the right direction, however...".

That's a contradiction. You can't have it both ways.  Either there's evidence that PE classes help or there isn't. You can't say research shows that PE has no effect on weight but PE classes will help anyway.

If you read a lot of news about various studies you'll see that it's a common error. When people really want to believe that X works they have a hard time accepting evidence that doesn't support their belief. You will find statements such as "There's no evidence that X helps Y but based on our theories/logic, we believe X should help Y so we should keep doing X". 

The other common response is "The evidence shows no link between X and Y but that just means we need even more X".  In other words, "My belief that X works is still correct, we can ignore the data because we were wrong about how much X we needed".

That response also shows up in the article linked: "..researchers said that PE classes were falling short and suggested a curriculum where children get more activity than classes currently offer".