Just like Barbie's proportions are improbable, the new Batman's proportions are a 30inch waist, a 57 inch chest, and 27 inch biceps. Both Barbie and the new Batman would have major health issues if they were real people, but people don't see that. Let's face it, people see what they want to see, and ignore what they want to ignore. People today become so obsessed with becoming successful, climbing to the top of the corporate ladder, that they are blinded to the dangers they put themselves in. In these societies plumpness is actually considered attractive and desirable.
People associate the extra weight with prosperity, fertility, success and economic security.
Even in poorer countries, an obese body is considered a healthy body for two reasons. First, fat deposits are good for surviving times when food is scarce. Second, people have to have a decent amount of money in order to afford food, and wealth means more medical care. People who are thin in these types of countries are considered malnourished and diseased. There are also a lower number of eating disorders in cultures where female social roles are restricted.