No worries. As long as you don't make a personal vendetta (which i've never seen you do) it is totally fine.
You also don't tell an obese person it is normal to be obese. You can still criticize it without being a total jerk to that person and it's then up to that person to do something (or not) with that feedback. They can still feel "offended" but that says more about their personality then yours. Just don't be mean and personal.