don't eat fast food christ.....you know why it's bad? it's because the fat is bad.
Instead just eat a lot of healthy food with good fat, then your weight will go up. and you health won't take a drastic plummet down, which it would if you ate junk food
eat meat and protein and carbs and starch like pasta. maybe some stuff from mc donalds. have ensure shakes
eat a 20lb baby or get pregnant
Eat a lot of fast food and candy
Eat hamburgers, candy bars, ice cream, pizzas, and drink lots of soda and that ought to do the trick for you.