Calories count. In order to maintain its functions, your body needs a supply of energy (in the form of calories) from the food that you eat. But how many calories do you need to consume each day in order to maintain, gain, or lose weight? This article provides a method for estimating your daily caloric needs.

You consume energy in the form of calories from the carbohydrates, proteins, and fats in the food that you eat. Alcohol also supplies calories.

Your body expends energy by performing bodily functions, such as respiring. This energy is called your basal energy. Your body also expends energy by performing activities, such as lifting a child, dashing for a bus, or riding an exercise bike. Your body also expends energy digesting and absorbing food. This energy is called the thermal effect of food.

To maintain your weight, you need to consume about as many calories as you expend. To gain weight, you need to consume more calories than you expend. To lose weight, you need to expend more calories than you consume.

When estimating the amount of calories you need to consume, you need to take into account basal energy needs, activity energy needs, and the thermal effect of food.

Step 1 – Determine Weight in Kilograms

To begin calculating your total energy needs to maintain weight, first determine what your actual weight is in kilograms by dividing your weight in pounds by 2.2.

To begin calculating your total energy needs to lose or gain weight, first determine your desired weight in kilograms by dividing your desired weight in pounds by 2.2.

EXAMPLE: 150 pounds is your actual or desired weight. To calculate your weight in kilograms, divide 150 by 2.2. The result is 68.18.

Step 2 – Calculate Basal Energy Needs

Your basal energy needs vary based on your sex.

If you are a woman, your basal energy needs are met when you consume an average of 0.9 calorie for each kilogram of weight per hour. Therefore, to account for basal energy needs, multiply the result of Step 1 by 0.9, and then multiply that result by 24 (for the 24 hours in a day).

If you are a man, your basal energy needs are met when you consume an average of 1 calorie for each kilogram of weight per hour. Therefore, to account for basal energy needs, multiply the result of Step 1 by 1.0, and then multiply that result by 24 (for the 24 hours in a day).

EXAMPLE: If you are a woman, multiply 68.18 by 0.9 and get 61.362, then multiply 61.362 by 24 and get 1472.688. If you are a man, multiply 68.18 by 1.0 and get 68.18, then multiply 68.18 by 24 and get 1636.32.

Step 3 – Calculate Activity Energy Needs

Your activity energy needs vary based on how active you are. The more active you are, the more you calories you need to consume.

If you are barely active at all (you sit most of the day), your energy needs will be about 30% of your basal needs, so multiply the result of Step 2 by 0.3, and then add that result to the result of Step 2.

If you are lightly active (you are on your feet a good portion of the day), your energy needs will be about 50% of your basal needs, so multiply the result of Step 2 by 0.5, and then add that result to the result of Step 2.

If you are moderately active (you exercise, garden, move in your job), your energy needs will be about 60% of your basal needs, so multiply the result of Step 2 by 0.6, and then add that result to the result of Step 2.

If you are highly active (you exercise vigorously or perform heavy physical duties), your energy needs will be about 75% of your basal needs, so multiply the result of Step 2 by 0.75, and then add that result to the result of Step 2.

If you are extremely active (you are an athlete or fitness professional), your energy needs will be equal to (100% of) your basal needs, so double the result of Step 2.

EXAMPLE: If you are the moderately active woman, multiply 1472.688 by 0.6 and get 883.6128, then add 883.6128 to 1472.688 and get 2356.3008. If you are the highly active man, multiply 1636.32 by 0.75 and get 1227.24, then add 1227.24 to 1636.32 and get 2863.56.

Step 4 – Calculate the Thermal Effect of Food

The thermal effect of food is 10% of the amount of calories you have calculated for basal and activity energy needs. Therefore, to calculate the thermal effect of food, multiply the result of Step 3 by 0.1. Add the result to the result of Step 3, and you have estimated your total caloric needs for one day.

EXAMPLE: If you are the moderately active woman, multiply 2356.3008 by 0.1 and get 235.63008, then add that to 2356.3008 and get 2591.93088. You need to consume about 2600 calories per day. If you are the highly active man, multiply 2863.56 by 0.1 and get 286.356, then add that to 2863.56 and get 3149.916. You need to consume about 3150 calories per day.