diet is easy, fresh meats, fruits, veggies and nuts. Avoid processed foods, anything in a can or box. Weigh all your food and look up nutrients on the USDA nutrient database so you can track calroies (and carbs, protien, fats if ya want).
Monitor results via scale and bodyfat testing. After a few weeks of getting baseline measurements if weight/bf is holding steady add more food to gain remove 300-500 cals a day to lose.