Protein intake:
For athletes protein is one of the most important nutrients to keep track of, without it the body is unable to recover, build, and repair as effectively. A lack of protein can even lead to muscle loss even if you keep active and continue to workout. Most research recommends between 1.2 to 2 grams of protein per kilogram of body weight per day, which is about 0.5-0.9 grams of protein per pound of body weight.
Link to MSU article: https://www.canr.msu.edu/news/protein_intake_for_athletes
research articles supporting claim: https://www.sciencedirect.com/science/article/abs/pii/S221226721501802X
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5477153/
In addition to improving strength and endurance of muscles, consuming high quality protein foods or drinks have been shown to reduce muscle soreness/fatigue as well as help stimulate muscle growth. The article linked above from the National Library of Medicine is a great read and has a ton of research packed into one long article. I would recommend looking through the "key points" of each section if you are interested.
Counting Calories:
Getting in the habit of counting calories is tough and tedious, but very rewarding and can really help create healthy eating habits and nutritional awareness. Cutting out a lot of low quality and high calorie foods and replacing them with nutritious meals can lead to feeling way more energetic and healthier than ever.
Give best approximations and write down total caloric intake after each meal, including snacks.
The general caloric goal to maintain current body composition is called a basal metabolic rate (BMR).
Here is a calculator that gives an approximation of an average BMR for given measurements: https://www.calculator.net/bmr-calculator.html
Having caloric intakes that are below or at the goal does not mean you will lose weight. Sometimes, you might even gain weight during a caloric deficit because of the muscle gain from working out.
Dieting
There are many different dieting strategies out there, from intermittent fasting to multiple small meals throughout the day. Different dieting strategies will fit different people depending on many different environmental and physiological factors.
We do not reccomend fasting, since growing bodies need constant high quality foods. The standard meal plan of 3 meals and snacks in between should be adequate for kids ages 7-18.
Extra videos on nutrition and healthy recipes (old posts)
Video on Omega 3 and some recipes:
Video on cooking healthy meals and more recipes:
