I feel the point is more nuanced than you suggest. Clearly, nobody should be made to feel shit because they are overweight, but that's quite different from being actively proud of being overweight. It feels like a fine line to walk - making sure people feel happy and confident in who they are, but at the same time empowered and supported to make life improving decisions without feeling they're "letting the side down".

This. I absolutely didn’t suggest anything like what the above comment projected and implied.

Public health is just an aggregation of facts about individual health right? Leaving aside the enormously important exception of epidemiology.

Obese people have poor health outcomes, which harms them. Insofar as it's meaningful to even say "harming public health", this harms public health. But since a collection of data is hard to harm, I think this framing is unhelpful.