In recent news, the US has finally been overtaken as the world's fattest nation by Mexico. This actually means the fattest major nation - there are some countries with very small (numerically) populations that have an even bigger weight problem, but they tend not to show up on world statistics. For example, there are only 10,000 people in the Cook Islands in the Pacific, but their obesity rate is over 60 per cent and almost everyone is overweight.
In Mexico the obesity rate is about 30 per cent, with around 70 per cent of adults being overweight. So almost one person in three is now obese. As a country Mexico has a lot of poverty - about half the population is officially poor - but it is thought that a lot of the increase in obesity is down to people having more disposable income, added to a lack of awareness about healthy food.
You can read more about this here.