When you eliminate junk food from your diet, there is more room for nutrient-dense foods that supply the vitamins and minerals you need for good health. Most junk foods contain too much saturated fat, sodium or sugar to be considered healthy, but replacing them with fruits, vegetables, lean meat and whole grains will supply essential nutrients such as fiber, protein, calcium, vitamin C and vitamin A. Getting sufficient amounts of key nutrients supports a healthy skeleton, heart, brain and digestive system. It also boosts your immune system.