Fuel your body right: How to accurately calculate your energy needs
How much do I need to eat in order to lose weight, gain muscle or improve my performance?
This is one of the most frequently asked questions I receive from my clients, friends and family on a daily basis. It seems like a pretty simple question, right? Wrong. The ultimate solution is to come up with the total number of calories you need per day to achieve your goals. The answer is different for everyone as we are all unique individuals. Using myself as an example, I will guide you through the process to determine what your caloric needs are based on your individual situation. By the end, you should be able to confidently calculate and apply your caloric expenditure to your everyday life and reach your fitness goals!
The first thing you want to do is determine your resting metabolic rate, or RMR. This is the amount of calories needed in order for your body to maintain its current weight at rest. By rest, I mean sedentary, if you were to lie still in a dark room without engaging in any activity all day. To determine your RMR, we will use the Harris-Benedict Equation. Keep in mind the calculations differ between men and women. Here are the formulas for each,
RMR = 88.362 + (13.397*Body weight in kilograms) + (4.799*Height in centimeters) – (5.677*Age)
RMR = 447.593 + (9.247*Body weight in kilograms) + (3.098*Height in centimeters) – (4.330*age)
– Converting pounds to kilograms – Divide the number of pounds by 2.2.
– Converting inches to centimeters – Multiply inches by 2.54
I will use myself as an example. I currently weigh 186 pounds. I would take 186/2.2 = 84.54 kilograms. My height is 5’9” or 69 inches. I would take 69 x 2.54 = 175.26 centimeters. Now that we have weight in Kg, height in cm and my age of 27 we can plug these numbers into the equation to get my RMR.
Men – RMR = 88.362 + (13.397*84.54) + (4.799*175.26) – (5.677*27) = 1908Cal
Now that we know my resting metabolic rate is 1908 calories we can move on to the second step. We need to figure out your daily activity level to factor into calculating your caloric needs.
Determining your daily activity level can be tricky. It is a measure of your day to day activities, but does not take into account structured and scheduled exercise. The scale measures from a 1.1 to a 1.5. For example, a 1.1 would be for someone who works in an office behind a desk for most of the day with minimal physical activity during or after work. Whereas a 1.5 would be for someone who works a physically strenuous job, perhaps in construction, then comes home to a very active family life maintaining a household. This is where you will have to do some critical thinking and place yourself reasonably within the scale.
For myself, I live a pretty active lifestyle. I spend a large portion of the day working with clients in the gym, take my dog for walks in the evenings, so it’s safe to say I’m generally on my feet all day long. To be conservative, since most of my day is spent indoors, I put myself at a 1.3 on the activity scale.
RMR 1908 x 1.3 = 2480cal
Now that we have our activity level factor added in to our resting metabolic rate, we can move on to the third step. Calculating the calories you have burned throughout structured and scheduled exercise. For some of you that have a heart rate monitor, like the Armour 39, which calculates calorie burn during a workout, this will be easy. However, there are people like me who aren’t that technologically advanced that will have to go to the internet for help.
This website is a wonderful tool for calculating energy burned during your workouts. You just plug in age, weight and gender and enter in the amount of time you plan on doing a particular workout. For myself, this month I am lifting weights at a moderate intensity for 1.5 hours a day 6 days a week for a total of 9 hours per week. In addition to that, I am logging roughly 3 hours of running at a 6 mph pace. When you input that information into the site, it comes out to a total of 5,524 calories per week divided by 7 comes out to an additional 789 calories per day.
2,480 + 789 = 3269cal
Now for the final step, what is your goal? Are you trying to lose weight, increase muscle mass or improve your performance? In order to lose weight it is normal to subtract 300 for females and 500 calories per day for males in order to lose an average of 1 pound a week. In order to add muscle it is safe and easy to add on anywhere from 300-500 calories a day depending on how fast or slow you want to bulk. Finally, for improved performance in a particular sport, you want to stay close to your daily caloric burn and even go slightly over. This way, you are giving your body everything it needs to perform at its best and recover most efficiently without putting on any significant weight.
One of the most important factors to keep in mind is that while there are a lot of numbers and formulas, these calculations are not exact. For example, through these calculations we’ve formed the conclusion that my caloric needs for weight maintenance are 3269 calories per day. When in reality, I am currently losing 1lb a week at roughly 3200 calories per day. This means that my true daily caloric expenditure is around 3700 calories per day.
These calculations are a great starting point to help you reach your health and fitness goals, but please be aware there will be small tweaks and changes necessary in order to truly fine tune your exact needs along the way.
Until next time, stay happy, stay healthy and stay active!