Energy Needs and Their Impact on Health & Fitness Goals – Part I

Part I – How do I figure out how many calories I should be eating?

I’ve decided to do another multi-part series as my previous series involving resistance-training variables has been received with rave reviews (thanks for the support, by the way). The first part will provide a general introduction to the concept of energy and calories and begin to explain how someone can go about determining how many calories they should be consuming. The remaining parts of the series will take a deeper look into the major components that go about making up daily caloric needs. My goal for this series is to provide a fairly in-depth discussion about a topic that is honestly relevant to any fitness or sports-minded person who wants to gain or lose weight. Back to the question at hand…

For starters, I’ll say that the U.S. FDA recommends that women consume a balanced diet that comprises a total of 2,000 calories per day and men 2,500 calories per day. This can be found on the back of any food label. What exactly is a calorie? A calorie is a form of energy; heat energy to be exact. To be even more exact, did you know that today’s common-day use of the word calorie actually infers kilocalorie (or 1,000 calories)? This can also be seen on food labels and packages as ‘kcal’. If you look up the actual definition of the word calorie (I decided to spare everyone that pain), you’ll see it’s an extremely small amount and for that reason we talk about it in multiple of 1,000 or kilocalories. Our body consumes this form of energy in the food we eat and our body converts it into other forms of energy. For example, heat energy can be converted to chemical energy, which is needed for successful completion of any one of the thousands of chemical reactions that occur spontaneously in all of the cells of our bodies. Enough science stuff for now, but my high school physics teacher would be so proud ☺.

The sum total of all calories expended by our body is often referred to as total daily energy expenditure or TDEE. This includes calories burned from exercising, digesting food, staying warm (or cool considering the time of year and nationwide heat wave) and simply staying alive. If we attempt to break up TDEE into its components we will end up with three: 1) Resting energy expenditure (REE), 2) Thermic effect of food (TEF) and 3) Thermic effect of exercise or physical activity (TEPA). It will be deeper discussions on these areas that are the focus of the remaining parts of this series on energy. For this reason, the complete answer to the question won’t come until these other articles have been developed. So stay tuned.

Remember now that basic proponents of weight loss and weight gain suggest that the balance between how many calories you burn each day (TDEE) and daily calories you consume in your diet must be tilted accordingly to result in your desired outcome. Because the total number of calories burned on a daily basis typically varies a great deal as does the amount of calories we eat, the process of weight loss or weight gain becomes slower and more challenging than it appears when just crunching some numbers. A cop-out answer to the question is that it depends on the person’s goal, how much they are currently eating and how many calories are currently being burned. I realize this is frustrating, but you MUST realize that it’s these factors that have to be corralled day in and day out for the scales to tilt in the direction you desire. Yes, other factors exist, but it’s these three factors that I strongly feel should make up the majority of your focus and attention. The numbers only work if the end result of your efforts tilts the scale in your favor. This is a harsh reality because most people underreport how many calories they are eating on a daily basis by 25 to 30% and when asked about exercise, most people give themselves too much credit and over report these numbers by 25%, resulting in an false state of reality that becomes all too sobering when you ramp up your workouts and cut back on your favorite foods. You expect the scale to move and reward your efforts, but it may not or it may move slower than you thought it would. It requires constant vigilance and remember there are calories hiding everywhere, so when you think you are consuming a certain amount of calories, it’s a pretty good bet you can add 15 – 20% to this amount and this will get you closer to its actual amount of calories. As much as I didn’t want this topic to turn into another ‘calories in vs. calories out’ discussions, this concept is at the center of this discussion.

Take-home messages from this article should be that TDEE is made up of three major parts: 1) REE, 2) TEF and 3) TEPA. Balancing TDEE against your daily caloric intake is considered by many experts to be one of the first steps to determining how many calories you should be consuming in your diet. The next article in this series will break down the resting energy expenditure (REE) component of TDEE and highlight what it’s comprised of and what factors exist to change it.