Well the fat acceptance movement is more popular because more and more people are becoming obese by the day and it's easier for them to try and force everybody else to adopt their standards rather than try and change and start eating right and exercising. The whole fat acceptance movement is stupid and ridiculous, imo, because weight is completely controllable the vast majority of the time. It's one thing to be pissed off by facing discrimination due to an uncontrollable feature such as race, height, or sexual orientation, but it's another to be pissed off for people pointing out that you're unhealthy and that you need to make a change.
I think part of the difference is a gender issue also. Women will always get more support than men in any kind of movement due to what's expected of the gender. Women are supposed to need protection and care and men are supposed to be strong and not show any emotions that indicate weakness, so a movement to help female issues is more comfortable for a lot of people than a movement to help men of any type.
The FA movement is futile though. I don't think obesity will ever be considered attractive no matter how many people try and make it so.