'No point' telling obese people to exercise more

[Matt1]

I think that first and foremost all human beings have freewill that needs to be respected and honored, if they choose to be a certain size and have a certain life style then i don't have a problem with it. I think its equally interesting to look at the psychological reasoning behind both points of view. Why do people have such an aversion to over weight people? and why do people become overweight to begin with? What is the mental and social conditioning, i believe it won't be as straight forward as what it may seem.