Things You'll Need

Instructions

1

Calculate your resting metabolic rate, which is the amount of calories your body needs to perform everyday tasks such as breathing, cardiovascular activity, digestion, etc. To calculate your resting metabolic rate, multiply your weight by 10. For example, if you weigh 145 pounds, 140 multiplied by 10 equals 1,400. A resting metabolic rate of 1,400 means you need at least that many calories for your body to function before any type of workout.
2

Calculate you daily activity burn. This figure is the amount of calories you need to complete movements besides those included in daily exercise. Things like housework, movement during your job, bathing, are included in this figure. To calculate your daily activity burn, multiply your resting metabolic rate (figure from Step 1) by 20 percent. Using the example from Step 1, 1,400 multiplied by 20 percent, or .20, equals 280. The daily movements for a librarian may be significantly less than those of a firefighter. This number is meant to be a guideline based on averages.
3

Add the calories required for your exercise needs to the figures obtained. P90X has determined that 600 additional calories are required to adequately fuel the workout. Continuing with the example 1,400 plus 280 plus 600 equals 2,280. This figure equals your total energy amount.
4

Compare your energy amount to the level chart located in the P90X nutrition guide to determine the appropriate nutrition level. Each level has a caloric range. The number of 2,280 is located within the level one range of 1,800 to 2,399. Round your caloric intake to the bottom number of your level. 2,280 rounds down to 1,800, the beginning number of the level one range.
5

Locate the appropriate meal plan for your phase and level. The meal plan will suggest meals that will provide the appropriate fuel for each phase of the workout. Many of the meal plans follow a high protein low fat approach. Phase three is only phase that incorporates carbohydrates. This is to accommodate for the long strenuous workouts of phase three.