Junk food plays a major role in the obesity epidemic. Children who eat fast food as a regular part of their diets consume more fat, carbohydrates and processed sugar and less fiber than those who do not eat fast food regularly. Junk food in these children's diets accounts for 187 extra calories per day, leading to 6 additional pounds of weight gain per year. Obesity increases your risk for cardiovascular disease, diabetes and many other chronic health conditions.