What I've learned about TDEE

Total Daily Energy Expenditure is probably the most important number anyone interested in losing weight should know. Eat above TDEE and you will gain weight, eat below and you will lose weight, eat at TDEE and your weight will stay the same.

The devil, of course, is in the details. Researchers have come up with formulas that can give most people a reasonable approximation of their TDEE. Those formulas however will not give a precise number and in some cases won’t even be close to accurate. Actual TDEE depends on a number of factors that are simply not accounted in the formulas that websites, apps and other online tools use. So, what really determines your TDEE? As far as I know, TDEE depends basically on the following:

1. Total body mass. You need energy to stay alive. The more of you there is the more energy you need .

2. Body composition. Not all tissue requires the same amount of energy, muscle needs much more than fat to be maintained.

3. Age. As we get older we use less energy. I don’t know if it is actually caused by the decrease in activity and muscle that usually comes with age or by something else.

4. Sex. Males have a higher calorie requirement. For males and females of the same height/weight/age, for instance, the Harris Benedict formula can predict differences of over 18%. I don’t know if this comes only from men having (generally) more muscle than females or from something else.

5. Activity level. Clearly, energy is needed to perform normal daily activities and exercise.

6. Caloric intake. This can be broken down in three ways:
a. Just as any other bodily function, processing food uses energy. The amount of energy needed depends mainly on the caloric intake.
b. Composition of diet. Not all foods require the same amount of energy to process. Protein requires much more than fat. Carbs are somewhere in between.
c. A low calorie diet can induce hormonal changes that reduce the body’s energy requirements.

7. A myriad other factors such as hormones, health conditions, genetics, stress, etc.

What to do with this information? I can only share what I’ve learned:

-The number MFP, Fat2Fit or other sites give is an estimate. My actual needs are close but different.

-I should measure my progress and adjust periodically. My own body will tell me if I need to eat more or not. In the end getting to know my own body is one of the many rewards of becoming healthy/fit

-Focus should be on what I can change. I will have to deal with the genetics I’ve got, but I can – and will - change my body composition, my activity level, and my diet.