**** This content is for educational purposes only, and does not substitute professional medical advice or consultations with healthcare professionals.****
This article is long overdue, and admittedly a welcome distraction from finishing my ebook on Creatine Monohydrate. Though this has some self-serving motives, it is something I have long wanted to do for my readers as the need for proper fueling is of utmost importance for those who are active. It is important for everyone, mind you, yet for those who engage in higher intensity activities like resistance training, crossfit, interval training, gymnastics, calisthenics, running, martial arts etc. When pushing yourself with exercise, your body is placed under greater stress and the need for adequate calories to adapt and recover is vital to ensure your health is not being sacrificed. You’ll often hear me stress this in my posts, and now I am giving you one of the tools to better understand your needs and ensure you are eating enough to support your body as well as your training.
DISCLAIMER: If you have a history of disordered eating and you know that calorie tracking is a trigger for you, this article isn’t for you. There are other ways for you to go about ensuring adequate fueling so don’t feel pressured to take up tracking if you know it is not right for you. If you’re feeling lost, seek out the guidance of an RD to help set you on the right track in a way that doesn’t conjure up any old habits that don’t serve you.
What I am going to provide you here are equations (or links to calculators) that will provide you with an estimate of your caloric needs. This means that your actual maintenance calories may be higher or lower than the number provided. Once you have calculated your initial estimate, all you will need to do is to eat that amount for 2 weeks and monitor your weight. If you stay relatively weight stable during that time, you have found your maintenance calories. If you lose weight, you’ll need to eat more. If you gain weight consistently over the 2 weeks, you’ll need to eat less. I’ll teach you what to look for and how much to adjust things later on in the article series. For now, all you need to know is that these numbers are estimates and you’ll need to try them on for size to see if they fit.
Now, enough chat. Let us get busy calculating.
CALCULATING YOUR BMR
Do you have an estimate of your body fat percentage?
Which equation you use will depend on whether or not you have a good estimate of your body fat percentage. If you know your body fat percentage then you can calculate your calorie requirements based off of your body composition. This is usually your best bet for getting a pretty good estimate of your requirements right from the start. You can measure your body fat via more expensive methods such as a DEXA scan or underwater weighing, or you can get a less accurate, but still useable estimate via something like calipers. It helps to have someone familiar with measuring via calipers to measure your skinfolds for you, but it is easy enough to learn that you can measure yourself and have someone close to you measure the skinfolds that you can’t reach. Many gyms offer body composition assessments where they give you an estimate of your body fat percentage. How accurate this number is will vary based on the method used, but at the end of the day they are all just estimates and you don’t need to get too worked up about it. You can use an electronic scale if desired, but know that these numbers are likely to be the least accurate. At the end of the day, we just want to have some general idea of where you are at. So, use the method available to you if you want to calculate your maintenance calories based off of your body composition.
‘I have an estimate of my body fat percentage. What now?’
If you have an estimate of your body fat percentage, we’ll calculate your maintenance calories using the Katch-McArdle equation. This equation takes into account your body fat and lean mass when estimating your Basal Metabolic Rate (BMR). I find this to be the most accurate for active women and it is the one I use with my clients.
If you are wondering what your BMR is, simply put, it is the amount of calories that your body needs to support itself at rest. For sedentary people, this number makes up the majority of their daily calorie expenditure, but no one who moves about even a little bit would have maintenance calories that are the same as their BMR.
QUICK RANT: As a rule, one should avoid eating too close to their BMR for an extended period, and one should definitely avoid eating below this number. As the definition above suggests, your BMR is how much your body needs to carry out everything that it needs to keep your body functioning if you did nothing else all day. Women often jump on diets that have them eating at, or even below their BMR calories right from the get-go which makes it unnecessarily aggressive, difficult to sustain and makes them feel like absolute crap. When eating so little for extended periods, one also runs the risk of negatively impacting their health and bone density in the long run as the body doesn’t have enough fuel to support its basic processes much less optimize health [1]. Such aggressive approaches may also have undesirable effects on your body composition as they may result in a greater amount of muscle loss, especially if you are relatively lean to begin with. [2] This is especially problematic if you regain the weight that was lost because you may end up at a higher body fat percentage than when you started, as your body will be more primed to regain fat and not muscle. [3] If your goal is to lose fat, the aim should be to only remove just enough calories to make that happen and no more. Starting your diet on calories that are around your BMR is the exact opposite of that.
Back to calculating your BMR. What is the Katch-McArdle equation?
The Katch-McArdle equation:
BMR = 370 + (21.6 x LBM in kg) Where LBM = [total weight (kg) x (100 – bodyfat %)]/100
I hate math so if this makes your eyes cross, I hear you. I’ll do my best to make it easy for you to understand, but if you are not interested in doing the math yourself, skip down to the end of this section to ‘PLEASE DON’T MAKE ME DO MATH!’ and you will see a link to a calculator. There you can just punch your numbers into and it will give you your BMR estimate!
If you want to understand how to do the math yourself, you’ll want to start with the part of the equation in red:
BMR = 370 + (21.6 x LBM in kg) Where LBM = [total weight (kg) x (100 – bodyfat %)]/100
This is where we use your estimated body fat percentage to calculate your Lean Body Mass (LBM).
Let us say that you weight 150lbs and are 25% body fat. You might have notice that the equation uses kg so we will need to do a quick conversion. To get your weight in kg, all you need to do is divide your weight by 2.2
150/2.2 = 68.18kg
150lbs = 68.18kg
You can round this up to 68.2kg or leave it as is. Your call.
So now we have one number ready to go:
BMR = 370 + (21.6 x LBM in kg) Where LBM = [total weight (kg) x (100 – bodyfat %)]/100
Is now:
BMR = 370 + (21.6 x LBM in kg) Where LBM = [68.18 x (100 – bodyfat %)]/100
Now we need to subtract your body fat percentage from 100 to get this number in the equation:
BMR = 370 + (21.6 x LBM in kg) Where LBM = [total weight (kg) x (100 – bodyfat %)]/100
If body fat percentage is 25% then:
100-25 = 75
BMR = 370 + (21.6 x LBM in kg) Where LBM = [68.18 x (75)]/100
Now we have what you need to calculate your LBM and solve this portion of the equation:
BMR = 370 + (21.6 x LBM in kg) Where LBM = [68.18 x (75)]/100
Here we go:
68.18 x 75 = 5113.5
And now all that is left is to divide that number by 100 to get your LBM:
BMR = 370 + (21.6 x LBM in kg) Where LBM = 5113.5/100
5113.5/100 = 51.1
The LBM of the 150lbs person at 25% bodyfat is approximately 51.5 kg
Yay math.
Now that we have your LBM, we can estimate your BMR:
BMR = 370 + (21.6 x LBM in kg) Where LBM = [total weight (kg) x (100 – bodyfat %)]/100
Is now:
BMR = 370 + (21.6 x 51.5) Where LBM = [total weight (kg) x (100 – bodyfat %)]/100
And we now solve this portion of the equation:
BMR = 370 + (21.6 x 51.5) Where LBM = [total weight (kg) x (100 – bodyfat %)]/100
21.6 x 51.5 = 1112.4
Now you can drop that in to the equation and we are on the last step:
BMR = 370 + 1112.4 Where LBM = [total weight (kg) x (100 – bodyfat %)]/100
370+1112.4 = 1482.4
The BMR of the 150lbs person at 25% body fat is approximately 1482 cals/day.
It is fine if you round up or down the numbers along the way instead of working with decimal numbers. It won’t change your result too dramatically so you can do what is easiest for you.
Now that you have an idea of what your BMR may be, you can skip forward to the section ‘Calculating Your Maintenance Calories Using Your BMR’
‘PLEASE DON’T MAKE ME DO MATH!’
Hate math? I don’t blame you. If you are just interested in getting your BMR estimates using your body fat estimate, use this calculator.
After that, scroll on down to ‘Calculating Your Maintenance Calories Using Your BMR’
So what about those who don’t have an estimate of their body fat percentage? There is an equation for you too!
‘I don’t have an estimate of my body fat percentage! What now?’
If you don’t have an estimate of your body fat percentage, you can use the same calculator above and select ‘I don’t know my LBM’, or you can opt for the second equation, the revised Harris-Benedict Equation. Like the section above, if you don’t want to do the math yourself but are interested in using this specific equation, scroll down to the ‘PLEASE DON’T MAKE ME DO MATH!’ at the end of this section where I will link you to the revised Harris-Benedict equation calculator.
The revised Harris-Benedict Equation estimates your BMR using your weight, height and age, which are all things that you should know about yourself. I personally find that this equation tends to underestimate the requirements of active individuals so keep that in mind when using this one. There is a good chance that you are going to need your increase your calories from what it estimates, especially if you are someone who lifts.
The revised Harris-Benedict Equation:
For women: BMR = 447.593 + ( 9.247 x weight in kg ) + ( 3.098 x height in cm ) – (4.330 x age in years )
For men: BMR = 88.362 + ( 13.397 x weight in kg ) + ( 4.799 x height in cm ) – ( 5.677 x age in years )
Let us use our same 150lbs person who is 25% body fat. This person is female so we will use the appropriate equation for her.
This equation also requires you to use your weight in kg so we will start with that simple conversion. To get your weight in lbs to kg, all you have to do is divide it by 2.2:
150 / 2.2 = 68.18
You can round this up to 68.2kg or leave it as is. Your call.
Now that we have her weight in kg, we can pop that number into the equation:
BMR = 447.593 + ( 9.247 x weight in kg ) + ( 3.098 x height in cm ) – (4.330 x age in years)
Now turns into:
BMR = 447.593 + ( 9.247 x 68.18 ) + ( 3.098 x height in cm ) – (4.330 x age in years)
And now we can solve that portion in the brackets:
9.247 x 68.18 = 630.46
And now our equation looks like this:
BMR = 447.593 + 630.46 + ( 3.098 x height in cm ) – (4.330 x age in years)
Alright, one down, just a few more steps to go.
Let us say that this 150lbs woman is 5’5’’. We will need to convert that to centimeters. To do that, first we have to convert it to inches. To get your height in inches, multiply the total number of feet by 12 and then add the remainder. So 5’5’’ in inches is (5 x 12) + 5
5 x 12 = 60
60 + 5 = 65.
65 inches.
Then multiply your height in inches by 2.54 to get your height in centimeters.
65 x 2.54 = 165.1
Her height in cm is 165.1cm
Now we can solve this portion of the equation:
BMR = 447.593 + 630.46 + ( 3.098 x height in cm ) – (4.330 x age in years)
Now it becomes:
BMR = 447.593 + 630.46 + ( 3.098 x 165.1 ) – (4.330 x age in years)
And we can solve that:
3.098 x 165.1 = 511.48
And now our equation becomes:
BMR = 447.593 + 630.46 + 511.48 – (4.330 x age in years)
Alright! Almost there.
Let’s say that this 150lbs lady at 25% body fat and a height of 165.1cm is 25 years of age. Thankfully all we need to do is pop that number in the equation here:
BMR = 447.593 + 630.46 + 511.48 – (4.330 x 25)
And solve:
4.330 x 25 = 108.25
And now all that is left is some basic addition and subtraction:
BMR = 447.593 + 630.46 + 511.48 – 108.25
447.593 + 630.46 = 1078
1078 + 511.48 = 1589.48
1589.48 – 108.25 = 1481
The BMR estimation is 1481cals/day.
Interestingly, that is one calorie off of what I got for this same woman using the Katch-McArdle equation!
So now you have your BMR estimation based off of your height, weight and age, now you can move on to the final step which is ‘Calculating your Maintenance Calories using your BMR’!
PLEASE DON’T MAKE ME DO MATH!
Hate math? I don’t blame you. If you are just interested in getting your estimates using the revised Harris-Benedict equation use this calculator
NOTE: This calculator will give you both your BMR and maintenance calories (TDEE) once you put in all of your information it asks of you. This means that you won’t need to complete the section below called ‘Calculating Your Maintenance Calories Using Your BMR’. From here, you can get busy eating!
CALCULATING YOUR MAINTENANCE CALORIES USING YOUR BMR
Once you have your BMR estimate, all that is left is to take into account your activity levels throughout the day. Depending on what yours are, you will multiply your BMR by the corresponding activity factor.
ACTIVITY FACTOR GUIDE
Sedentary – Little to no exercise each week = Activity factor of 1.2
Mildly Active – Mostly light exercise 1-3 days a week or intense exercise for no more than 20 mins 1-3 days a week. If you are someone who does not exercise but moves about a lot throughout the day, this activity factor could work for you too. = Activity factor of 1.375
Moderately Active – Intensive exercise for at least 30 to 60 minutes 3 to 4 times per week. Most gym goers would fall under this category – Activity factor of 1.55
Heavily Active – If you work a labor intensive job or exercise heavily for 60+ mins, 5+ days a week. If you are involved in training for endurance events then you will likely fall into this category. This activity factor isn’t reserved for athletes only though. If you are someone who moves about a lot and trains 5 days a week, this activity factor may be better suited for you. Activity factor of 1.725
Extremely Active – This activity factor is mostly for competitive athletes, especially ones that train more than one session per day, and train most days a week. Some labor intensive jobs may push an individual into this category but you are more likely to need this activity factor as a competitive athlete, especially if you participate in endurance sports. Activity factor of 1.9
Once you have decided which category you fall into, simply multiply your BMR by the corresponding activity factor.
We will go back to our 150lbs woman with the BMR of 1482cals. Let us say that she resistance trains 2 days a week and goes for a jog 1-2 days a week depending on her schedule. She works a desk job but walks for 10 mins to and from work. I’d put this lady into the Moderately Active category. So we multiply 1482 x 1.55 leaving her at a total of 2297cals/day.
So, this woman needs approximately 2300cals/day to fuel her body for her daily routine plus all of the various processes happening within her body behind the scenes. This number is known as your TDEE or Total Daily Energy Expenditure. If she started walking more or training more, this number would go up even higher because her body would need more fuel to support the extra activity.
If you feel that you fall in between two categories you can go with the lower activity factor to start, or you can put yourself at an activity factor in between. For example, if you think you are between moderately active (activity factor 1.55) and highly active (activity factor 1.725) you can either go with 1.55 or try 1.65 which would be roughly in the middle. As I mentioned before this is clearly not an exact science so you don’t need to stress getting things perfectly. If you want to be conservative, start at the lower number and if you notice that you start losing weight, losing sleep, are not recovering as well in between sessions or feeling increased hunger, it means that you may have under estimated your activity levels.
Usually by this point if you are someone who is under eating, you’ll be a bit shocked at the difference between what your estimates are and what you are letting yourself eat. Unless you are very petite, chances are that your number is somewhere in the 2000s which is often a big shock to some women. Though there have been a handful of outliers, most women than I work with need 2000+ cals to maintain their weight and activity levels. The more active you are, the more that you need to eat. That is the reason why I have put aside this time to write this article for you. To help you get a better idea of how much you need so that you can fuel your body better and get the most out of your day and your training.
This is getting a bit long so I will wrap this up here. By now you should have your maintenance calories (TDEE) calculated which has armed you with a baseline number to troubleshoot. You can eat this amount for 2 weeks and monitor how your body responds. If you find yourself losing weight then this number is too low. If you steadily gain over the two weeks then you may need to decrease the number slightly. To learn more about the troubleshooting process and what to expect when you start eating at maintenance, check the article links below!
More in the series
Part Two: Setting Macronutrient Targets
[1] Wasserfurth P, Palmowski J, Hahn A, Krüger K. Reasons for and Consequences of Low Energy Availability in Female and Male Athletes: Social Environment, Adaptations, and Prevention. Sports Med Open. 2020;6(1):44. Published 2020 Sep 10. doi:10.1186/s40798-020-00275-6
[2] Helms ER, Prnjak K, Linardon J. Towards a Sustainable Nutrition Paradigm in Physique Sport: A Narrative Review. Sports (Basel). 2019
[3] Roberts BM, Helms ER, Trexler ET, Fitschen PJ. Nutritional Recommendations for Physique Athletes. J Hum Kinet. 2020;71:79-108. Published 2020 Jan 31. doi:10.2478/hukin-2019-0096
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