>eating healthy and exercising is not enough for a lot

That's because both these interventions when followed in the way they are commonly understood are near completely incorrect. I blame the govt/medical profession for this.

Other factors: again I blame govt/medical profession for this - example it's difficult to get unprocessed food unless one reads labels carefully. For example it is near impossible to get milk that is not fortified with vitamin D. As they say: the road to hell is paved with good intent.

Granted that even after doing everything right there will be some people who will be obese, but that would be the minority. Again the govt/medical profession is to blame - for example I've heard that infants/kids are now given around 30 vaccines. With so many variables that have changed in the environment it now becomes difficult to isolate what is causing the health issues that predispose people to a lifetime of ill health