An excellent book on this topic is The Obesity Code by Dr Jason Fung
Obesity is a public health problem, like tobacco smoking or STIs. There's no secret - avoid ling disease by not smoking, and avoid STIs by not having unprotected sex. But clearly the "it's stimple, just fix it" approach isn't effective at improving the overall health of a population.
I honestly don't care at all about the overall health of the population. I really don't. Not that I wish them any ill-will, but I can't even begin to muster up the slightest bit of care for people I don't know ruining their lives because they eat too much or smoke. It's just not even on my radar.
I realise I'm not supposed to admit this, but I also realise I'm not the only one who thinks it.
</sarcasm>