This was in a conversation about what kind of abusive behavior is acceptable. Do you think it's also acceptable to be mean to athletes because they too cause damage to their own bodies?

Did you equate

No, I was correcting YOUR comparison. I think shaming racists is quite good, while shaming fat people is misguided.

ignore all the medical and scientific evidence

The point here is that our value judgements about health aren't medical or scientific. Risky behavior isn't universally frowned upon by society. Often its encouraged.

In the US, for instance, automobile accidents are a lead cause of death for people under 35, yet we don't treat driving with the same disdain as smoking or obesity. As far as "lack of physical activity" goes, car accidents represent a major source of injuries, which do make people less able to keep up healthy lifestyles. Yet again, little disdain.

Smoking is a great comparison here, because if you want to take the medical literature seriously you can't just handle it from the consumer end, you also have to deal with industries that employ swaths of food scientists to make bad food addictive and cheap.

All in all, I do think we could benefit from thinking about why we shame people for things and ask ourselves if we're applying these judgements in a consistent way.