If you don't eat healthy, you will be stressed and you will have a lack of energy. There are many long term effects of unhealthy eating habits, including obesity, high blood pressure, high cholesterol, heart disease, type-2 diabetes, depression and certain types of cancer. You shouldn't eat alot of sugar because your teeth can rot. You need a balanced diet because you need a bit of veg, dairy alternatives and sugar. If you eat alot of sugar, youn will be come fat and the way to resolve that is to exercise everyday and have a balanced diet.