
1 We sometimes eat healthy food.
2 So that they feel healthy (good).
3 Healthy food is food that is healthy (obviously). Basically the opposite of junk food.
4 If you eat only junk food and sweets, since it has has so much calories and other bad things, it will be bad for your health. That's why you shouldn't eat too much junk food and also eat fruits and vegetables. There's no reason to not eat tasty food once in a while though..