On the one hand, fast food has been more convenient for the tourists and it's very cheap and tasty. Furthermore, it's the great way to expand the needs of one country. Besides, the fast food is very important industy to investment environment.
On the other hand, the fast food is maked of a lots of litter with salt, grease, food addictive, etc... so it's bad quality and contains many calories. In addiction, if we don't use a lots of calories, the fast food can be one way to make you overweight. Another problem is that if we eat fast food all the days, our nutrition can be unbalanced.
In conclusion, I think that the fast food isn't the good for our health. But if you're travelling and you want to eat something quickly, I think the fast food is a choice for you.