I really wish that I could agree with what you are saying, and I definently used to agree. (Don't want to cause a shitstorm, just want to talk about this in a friendly manner, I accept if I'm wrong about something)
Isn't there like a statistic that says that atleast 50% of obese parents get obese kids? I don't remember, but it is based on this statistic that I have a problem with obesity. Nobody wants to be obese, if there was a magical switch that made it so we were the ideal body for our age, we would definently flip it, right? So I don't think it's fair to push your unhealthy lifestyle onto your kids, before they get a chance to grow up and know what is good and bad. I personally think a big part of being a happy kid, is being healthy, and doing sport. It brings me a lot of happiness now(15M), that I wish I had, when I was younger.
So I think you definently have a point, but I don't think it's fair to the possible kids, the overweight people might have. Every parent wants to be able to play football with their child, to do fun stuff together. And I personally think that obesity hinders that, it's a container of how much happiness we can get. I don't think being obese is fair to yourself, when obviously nobody wants to be obese, it's not fair to your kids, they deserve to be healthy, and hopefully also have a healthy parent that will be there for them in a active way, for a long time. It's not fair to your family, and to your wife/husband, when they want to love you like when you were young.
But then again, I can't force anyone on how they should live their lives, but everyone deserves to know, that they will truly be happier if they aren't obese, or underweight. But maybe I'm wrong, maybe my problems stems form the fact that I see obesity(and generally wrong perspectives on body and physice) as a disease. Is it okay to be obese? I feel like it would be okay, if the only person your obesity effected was yourself, but it's not. (Sorry if I rambeled a lot to you, random internet stranger, just needed to get this out)