at the end of the day, obese people have a choice. okay, some obese people maybe do have a medical problem (although i have to admit im relativley skeptial of this, as i cant help thinking most use it as some kind of excuss!), but whats the point of freedom, if you cant choose to be fat, thin, slim, whatever. classic example. fatman from youtube, posts videos of himself eating stupid amounts of food, even though he does have diabeties (and seemingly learning difficulties due to his voice!), but as he points out himself, its life, his body, who can stop him? and really, why should they?
on the other hand...if obese people didnt travel on holiday, and had their passports revolked, wow, imagine the public reaction! would make a cool mockumentory! it might even have a positive effect in the long term, people would lose weight for the right to go on holiday!
as for helping the environment, im VERY skeptical of this green house effect...and personally believe oil will destroy us (haha! obviously not literally!) before anything seriously dangerous happens to the earth itself.