Being overweight shows laziness to me

How so? It's extraordinarily difficult to return to a normal body weight after becoming obese, only 0.5% of slightly obese people are able to manage it, and only 0.1% of the morbidly obese. They could be down 100 lbs, but at present they're still obese. Thus, you're expecting them to work harder than 99.5% of people by returning to a normal weight before they stop being "lazy". Based on the success rate, going from fat to normal sized is about as tough as a normal sized person becoming a professional athlete.

I suppose you could argue they were lazy at some point in the past, but most obese people are no longer gaining weight and about half are actively trying to lose it.