Some feel that the diet craze in the last few decades is at least partly responsible for the increasing rate of obesity in America. As a society, we have chosen to join together and share in the funding of public health care. We do not get to pick who deserves what portion of the resources available. Athletes use more health care services because they are at higher risk for broken bones, injuries to soft tissues, etc. Those who drive cars put themselves at greater risk for traffic accidents.
Older people use a majority of the public health care collar.
And to use a truly parallel example, poverty is a risk factor for most major diseases. Poor people use more public money on health care, and have worse outcomes. The difference is that our society does not disapprove of athletes or car drivers, and we recognize that it is unfair to blame poor people or old people for their greater use of health care resources. But when it comes to obesity, weight prejudice makes our society intolerant. We blame fat people for their condition no matter what the real cause.