There are very scientific terms that define a calorie, but the precise definition is better replaced by a simpler standard for our discussion. A calorie is a unit of measure for energy, that our body uses for all of our vital process. You are constantly burning calories, even during sleep, although the rate at which calories are burned falls dramatically while at rest.
The rate at which calories are used is constantly changing to meet the energy requirements of our body. This varies from person to person and during the different stages of life. For this reason when we discuss how many calories we need on a daily basis, the numbers are approximate estimations.
Calories as a Measure of Food Energy
When we speak of calories in relation to a particular food, we actually mean the amount of energy that that food provides for our body to fuel its' metabolic processes. So weight control actually comes down to a process of energy. If we take in more energy than we use, the rest gets stored as fat. If we burn more energy than we consume, our body relies on our energy stores to make up the deficit.
How many Calories Do I Need to Maintain My Weight
The most accurate way of determining how many calories needed per day is based upon your basal metabolic rate. However, this calculation is quite complex and involves multiple steps. An easier way to estimate the number of calories you need is a day is as follows:
- For sedentary people: Weight x 14 = estimated cal/day
- For people who are moderately active: Weight x 17 = estimated cal/day
- For active people: Weight x 20 = estimated cal/day
Between 20 and 50 percent of your body's energy requirements are determined by your activity level. The rest of the body's energy use is devoted to vital processes such as breathing, heartbeat, digestion, and cell processes.
Bear in mind that these numbers are estimations and your actual body processes may require more or fewer calories. Also, these numbers are the number of calories needed to maintain your present weight. These calculations do not take into account weight loss or weight gain.
Note: "Moderately Active" is defined as someone who has 3-4 aerobic sessions per week. "Active" is defined as someone who has 5-7 aerobic sessions.
How Many Calories Do I Need to Lose Weight?
To achieve a weight loss of 1 pound per week, you need to take the above number that you arrived at and subtract 500. This is the needed calorie deficit that will achieve a healthy, slow, and moderate weight loss, while fostering lifelong changes in eating habits. This calorie deficit can best be achieved by shaving 250 calories off of your food intake, and then engaging in physical activity to burn 250 calories. One of the easiest ways to eliminate calories in the diet is to eat slightly smaller serving sizes.