Calories in vs calories out is the easiest way to understand how a person’s body composition changes.
The body needs a certain amount of food for energy throughout the day, depending on how active they are. An athlete like Michael Phelps eats approximately 12 500 calories a day (over 5 times the amount of an ordinary person). The main reason for this is because he is so active with all the training he does. He will burn most of that food for energy. On the opposite side of the spectrum, a person who has an office job and isn’t very active at all may gain weight on 2000 calories. We need to find out our body’s calories maintenance level. This is the number of calories the body needs to maintain its current weight. Once we figure out the maintenance calories we can then increase the number of calories we’re consuming, if your goal is to put on muscle.
If you’re looking to lose weight, you drop the calories slightly below the maintenance level. A safe calorie deficit to start with is between 100-300 calories. Sticking to a small deficit ensures the body is still getting sufficient nutrients and energy. An extreme deficit will cause you to be tired, fatigued & hungry. After a while, the weight loss/muscle gain will plateau a simple increase or decrease (depending on your goal) will need to occur for progress to continue.
Calculate Your Calorie Intake by clicking on the graphic below. Calculator provided by bodybuilding.com