His weight is between the 25-10th percentile and his height is just above the 50th percentile for his age. He will be going into the teenage years and start growing. For his age, he needs daily approximately 2200-2500 calories a day as recommended the following; Fruits = 2 cups; Vegetables 3 cups; Grains (cereals, breads) = 8oz equivalents; Meat & beans = 6.5oz equivalents; Dairy products (milk, yogurt) = 3 cups; Oils = 7 tsp; Additional calories to be used discretionary = 365. This food needs to be divided up between 3 meals and snacks between meals daily. You can try a Heart Healthy diet which helps to stay healthy overall, however, he may not accept it due to his age. A Heart Healthy diet means a moderate fat diet to lower the fat content of your foods and increase ‘good’ fats to benefit your body. Moderate fat diet means = use polyunsaturated (omega 3, corn oil, nuts, etc) fats and monounsaturated (olive oil, canola oil, peanut oil, etc) fats, no saturated fats (high fat snack foods, butter, fat spreads) and no trans fats. Eat low fat meats (chicken, fish, loin of pork) or non-meat sources (soy products, nuts), low fat vegetarian combinations (rice & beans, pasta & beans, low fat cheese & pasta), low fat dairy and substitute dairy products (skim milk, 1% milk, low fat yogurt/cheeses, low fat soy milk/soy yogurt), use plant oils, non trans-fat margarines, and eat a lot of fruits and vegetables. Eat daily high fiber breads and cereals (oatmeal). Suggest setting an example by you eating healthy and hopefully your son will follow. Hoped this helped you.
My suggestion is stop giving him sugar. Period. This is very difficult unless you just don't keep it in your house. If you ONLY provide him healthy choices he'll eventually begin to crave more benificial foods. Don't use sugar as snack or reward (such as the after dinner cookie) at all. If its not in the house it's not an option and I know he will not starve to death. Maybe getting a little hungry would make other foods appeal to him more.