I'm a big believer in personal responsibility. No one forces you to eat at certain places, to eat specific things and to eat the whole thing.
I remember there was another documentry film maker who did the same thing as the "Super Size Me" guy, but she had different rules. She had to eat everything on the menu, but if they offered an upsell, you didn't have to take it. She lost 20-30 lbs. She made healthier choices more often. She also didn't have to finish every last bite. It's all about the choices you make.
I'm trying to teach my kids healthy eating habits. Sweets, yes. All the time or every day, no. They are a treat. I also tell them to stop eating as soon as they are full--no clean plates club here. I don't offer food when they are hurt physically or emotionally. We try not to eat just because food is there. I'm trying hard to instill a love of healthy foods (fruits, veggies, etc). I don't like Ketchup or Mayo, so I've never offered it to my kids and now they hate it too. Same with sour cream and guacamole.
Before healthy choices were available on kids menus, DH and I would order DS the chicken fingers, but could we have that grilled? And instead of the fries could we have a vegtable instead? Food runners used to be shocked when they saw our healthy kids meal. My kids are at least 2 before they ever have chicken nuggets or a hamburger. And again, this is an occasional treat. They get grilled cheese sandwiches instead--gotta love Sonic.
Vacation is major junk food time, but by the end of the week, everyone wants healthy food only. The thought of fries or a milk shake/ice cream just makes everyone sick. But, hey, we only vacation twice a year and even then it isn't ALWAYS junk.
It took me a long time to overcome all my bad eating habits. DH is still working on it. But it is all about the choices each individual makes. You can order the healthier meal, eat a smaller portion or you can find the most fattening thing on the menu and eat until it is gone.