In the 80's it was considered fact that homosexuality was a health risk. AIDs was a huge concern.
This is untrue. You could say "it was considered by some/many/bigoted people" but I doubt it was ever true that the same percentage of people with relevant medical experience thought homosexuality was as unhealthy as obesity.
Even if it were true, it would be a straw man unless you were also claiming that all gay people had AIDS and/or it was impossible to have gay sex without contracting HIV.
All obese people are obese. Inside that bucket of the population, some people are genetically or culturally predisposed, but some significant portion of obese people are capable of making healthier choices and are failing to do so. I don't think it's right to go out of our way to make these people unhappy, but at the same time I think it's obviously better for everyone if society encourages these people to make healthier choices.
Regardless, unlike obesity, no one can remove their homosexuality and it is fairly insulting to suggest that.
