I think depend of person, but I think nowadays both women and men are worried about their diet. Maybe 10 or 15 years ago women were more worried about their diet but today not.
I think that men and women have a different perception of being fat. Men and women approach weight loss differently. Losing weight is usually important to women. If the men don't see their weight as a problem, they're not going to do anything because many times they are happy so.