Most of us understand that weight management depends upon the energy balance equation; the amount of energy you put into your body (food calories) versus the amount of energy you expend (activity). But how do you know how many calories your body needs to reach or maintain a certain weight?
Understanding your body's energy requirements can help guide you when making
food choices. I'll show you two ways to determine your energy requirements, the accurate way and the easy way.
The Accurate Way
There are three primary components that make up your body's energy expenditure. Adding these three components together, basal metabolic rate, energy expended during physical activity, and the thermic effect of food is the most accurate way of determining how many calories your body requires each day.
1. Basal Metabolic Rate (BMR): Most of the body's energy, about
60-70%, goes to supporting the ongoing metabolic work of the body's
cells. This includes such activities as heart beat, respiration and
maintaining body temperature. To determine your BMR:
For adult males - Multiply the body weight by 10; add double the
body weight to this value.
[i.e., for a 150 lb male, 1,500 + (2 x
150)=1,800 cal/day BMR]
For adult females - Multiply body weight by 10; add the body weight
to this value.
[i.e., for a 120 lb female, 1,200 + 120=1,320 cal/day BMR]
2. Energy Expended During Physical Activity: The second component of the equation depends upon your level of physical activity. Physical activity has a profound effect on human energy expenditure and contributes 20-30% to
the body's total energy output. One of the most reliable methods in
calculating calories burned during physical activity is the Metabolic
Energy (MET) Method. Fitness Partner's
Activity Calorie Calculator
will calculate over 200 activities for you.
3. Thermic Effect of Food:
The last component to calculate has to do with your body's management of food. The increase in energy required to digest food is referred to as the thermic effect of food (TEF) and it's simple to determine:
TEF = total kcals consumed x 10%
[i.e., 2,000 kcals consumed/day x 0.10 = 200 kcals expended for TEF]
The Easy Way
If all of those calculations seem too confusing or tedious, you can roughly estimate your daily calorie requirements using this simple formula:
For sedentary people: Weight x 10 = estimated cal/day
For moderately active people
sessions/week): Weight x 13 = estimated cal/day
For active people
(5-7 aerobic sessions/week): Weight x
15 = estimated cal/day
Managing Your Weight