weight gain by doing different healthy and active things

Please provide evidence for this. You're using anecdotes to support your counter arguments and it provides very little to your overall goal of understanding the whole perspective. I think most of your understanding comes from the fact that you are easily convinced by your own anecdotes, but insufficiently convinced by hard evidence like those stated above.

It's easy to be convinced by perspectives that fit an already preconceived argument. If you're in here to truly have your view changed, you are showing an absolute stubbornness to your own perspective by using anecdotes as a counter argument to what you see. Put the same or more effort into your arguments you expect from others.