First consideration: Total Calories

How to Figure Out How Many Calories You Need Without a Visit to the Indirect Calorimetry Laboratory

Since we can’t figure out your carbohydrate or protein needs without first knowing your calorie needs, we have to focus on finding your calorie needs first.  There are several components that determine how many calories you burn.  However, it’s easiest to focus on two parts.  First, you have your “basal metabolic rate” which is how many calories your body needs to stay alive when at complete rest.  Secondly, you have your energy expenditure throughout the day through movement and exercise.

In order to measure your basal metabolic rate most accurately, you would have to find a laboratory to put you through an indirect calorimetry test.  In doing so, they will put you totally at rest and ask you to fast the morning before you do it (in order to make sure that they don’t measure any calories you spend to digest your food).   After you’re at rest, they will measure the amount of oxygen that your body consumes.  Then, they will use the fact that each liter of oxygen consumed means that five calories have been burned.  That is the most accurate way to find your basal metabolic rate, but it’s also pretty inconvenient and expensive.

In order to find out your energy expenditure throughout the day, the most accurate way is to look it up in Exercise Physiology textbooks.  In such a case, they figured out how many calories many types of activity consume by using indirect calorimetry.  Basically, they put someone in a giant box and have them do something (like get on a stationary bike at 10miles per hour, for instance).  Then, they measure how much oxygen that person used and multiply it appropriately to find the calories burned.  Although this method is accurate, it is fairly cumbersome for someone to use since they’ll have to input so many different values for all the different types of activity they did throughout the day.

Unless you’re a professional athlete, you’re probably not going to want to sit around and add up how many calories you’ve burned all day doing each different activity, add your basal metabolic rate to that, and then figure out how many calories you need for the day.  It can be done, but it’s not realistic for the majority of us.

So, how do we peons get along?  Well, the best way to have a good guess is to keep a food diary for three days that you stay the same weight.  The first step for the food diary is to eat.  Got it?  Good.  Second, write down everything you eat right after you eat it.  Do that for three days.  At the end of those three days, put everything into a calorie counter website (like or  Then, see how many calories you ate total and divide that by three to find your average daily caloric intake.  And, assuming that those three days were normal for you and you stayed the same weight, you now have an educated guess as to what your calorie needs are for the day.

This is effective because by using a food diary, we’re taking into account both basal metabolism and the energy needed for your lifestyle/exercise.  It’s an easy way to take everything into consideration all at once.

Now that we’ve knocked out the question of how many calories to eat, we can move on to the next question in Part 3.  “If I meet my calorie requirements, how much protein do I need?”