Actually according to the World Health Organization the United States is nowhere near the fattest country.
http://www.who.int/infobase/compare....gegroup=15-100 That reccord goes to Nauru, heck we're not even top five
Ideally: Bring back P.E. in school, make it a requirement. A tax based on % of body fat (because BMI isn't an entirely reliable measuring stick), ban HFCS (High Fructose Corn Syrup), ban hydrogenated oils, have centrally funded gym memberships where going is a requirement under penalty of fraud (would have to hit a certain % of days to avoid persecution), replace vending machines with ones that serve apples, subsidize raw fruits and vegetables to encourage low income families to purchase them instead of cheap calorie and sugar dense foods, ban escaladers, require elevator permits (don't have a condition, use the stairs), and television timers.
Eh Comrades?
Realistic: There is nothing one can do. They must make the choice themselves to change and no amount of pressure be it from friends nor government can make them change.