This is a huge topic and recommendations are very different person to person. If you are working out regularly, you need to consume food. Carbohydrates, proteins, and fats! Keep in mind that vegetables and fruit fall under the carb category, not only grains.
Male athletes between 14 – 19 years old need 3000-6000 cal/day and female athletes 14 – 19 years old need 2200-4000 cal/day.
Carbohydrates should consume 55 – 60 % of daily calories, with endurance athletes completing over 90 min of training consuming 6-10 grams of carbs per kilogram of body weight. Ex. a 200 lb athlete is 90.9 kg. 90.9 x 6=545 and 90.9 x 10 = 909. A 200 lb endurance athlete should consume 545-909 grams of carbs per day.
Protein recommendation is between 1-2 g/kg of body weight/day. More protein is needed for athlete’s that complete more resistance training.
Fat is used as an energy source and is essential for bodily functions. 20-25% of total calories should come from fats and of that consuming no more than 10% saturated, 10% polyunsaturated or 10% monounsaturated, and total no more than 30% of calories.
Calories can be scaled down based on age and overall activity level for adults. The first step is realizing what your current nutrition is like.
One way to accomplish that is by using Myfitnesspal, an app that serves as a food diary to show the breakdown of Carbohydrates, Protein, and Fat, as well as provide recommendations for total calories based on your goals.