Sugar has addictive properties, including withdrawal and relapse patterns similar to dependence forming drugs. It obviously doesn’t affect everyone the same way, but a subset of people are at a much higher risk. Make them poor and put them in a sedentary society where all cheap food is made hyper-palatable with excess sugar and fat and…drumroll… they turn obese.

Shaming all fat people isn’t much better than the old caricature of drunkard indigenous Americans. There’s systemic issues at play.