Junk food usually has very few nutrients and a lot of fat, sugar and salt. Your body can often get too much of these and so eating junk food on a regular basis can make you unhealthy. Some experts refer to junk food as "empty calories" meaning that the food contains lots of calories that are not particularly helpful to your body. Thus, by eating this food you are killing yourself and making you off-colour.
Not only is it low in calories and makes you unhealthy, you also may become overweight and full of fat. When you eat a burger, pizza, chips, or drink a coke; it has so much fat that you will end up having cholesterol in your body. Teenagers nowadays are very self-conscious, and they worry about how they look. They don't want to get
overweight and mess up their bodies in their teens, so they should consider not eating junk food for their bodies. Therefore, eating junk causes your body to become obese.