How many calories per day should you eat? That depends on how old you are, how active you are, whether you are still actively growing and your gender. Yes, it’s not fair, men can eat more than women; and children and adolescents need more food than adults; and active people just plain and simple need more food than inactive people.
This is just a guideline; you will have to adjust how many calories you need per day depending on whether you are gaining weight per week and what kind of weight you are gaining per week.
If you are gaining (or losing) about 1 pound per week that takes about 1,000 calories. It does not depend on whether it is fat or muscle. If you are gaining more fat (you know what it looks like) and not gaining muscle you need to eat less per day. If you are losing muscle and weight, then you need to eat more per day and to stay active. (If you are inactive and eat more you will build fat. If you are active and eat more you will build muscle.) The overall idea is to have more muscle than fat to keep yourself healthy. (Adult males should be between 11% to 21% fat, adult females should be between 13% to 25% fat.)
The amount of calories you need depends on how active you are, how large you are and your gender. If you do not move around (coach potato or office worker) you are sedentary. If you are doing things (playing, working out, running errands all day, walking lots; at the end of the day you are tired and slightly sore) they you are active. If you job or life style requires you to move large weights (manual labor, heavy work outs; at the end of the day your body is tired and sore) then you are very active. Of course, the larger you are the more calories you need. That is why most males need more calories than most females; but of course two people about the same size need about the same calories. Sorry adult women, adult men burn more calories than adult women all the time; adult male muscles are built differently then adult female muscles and as a result usually need more calories; but an inactive man with poor muscle mass needs the same amount of calories as a inactive women.
Very Sedentary Women or Inactive Older Adults need about 1,600 Calories per day.
For Children, Teenage Girls, Moderately Active Women and Sedentary Men need about 2,200 calories per day.
Teenage Boys, Smaller Active Men, and Very Active Women need about 2,800 calories per day.
Active Teenage Boys, Midsize to Large Active Men, and Extremely Active Women need about 3,500 calories per day.
Very Active Men need more than 3,500 calories per day.