Understanding your metabolism may seem like a daunting task, but the scientific community has teased out a few key factors that impact how much energy you expend on a daily basis. I recapped the most pertinent factors in detail in this post, but here's a brief description on how they impact your maintenance calorie level.
The vast majority of this number will come from your resting metabolic rate; the amount of calories your body would burn if you just laid around in bed all day long (and we've all been there). This number is largely tied to your current body weight and energy intake.
At an equivalent body percentage, the more you weigh, the higher your RMR. So the idea that larger people necessarily “have a slow metabolism” doesn't hold weight (pardon the pun). In fact, adding muscle mass is likely the best way to go about increasing your RMR; you could think of the extra calorie burn from having more muscle as "free cardio."
But it doesn't end there: energy expended during exercise, non-exercise energy expenditure (also known as NEAT) and the thermic effect of food all play a role in your total daily energy expenditure.
It's also worth noting that all of these values generally decrease during periods of prolonged dieting (1). There are various systems in place to conserve energy when your body perceives that food is scarce, so it's not surprising to find that all facets of energy expenditure trend downwards in that scenario.
This is a word to the wise: it's never a good idea to aggressively under eat for a prolonged period of time if you want your metabolism to operate at an optimal rate. Crash-dieting & endless cardio are off the table.
You can find your maintenance intake two ways: mathematically (with tweaks, which is where a coach comes in), or through trial and error (more on that later).
Various calculations can be used to determine each of these factors. The base of this calculation comes from the Katch-McArdle Equation (2), which uses your lean bodyweight (in Kg) to figure your resting energy expenditure.
Next, you can utilize a multiplier to estimate your activity level across the day. This multiplier varies slightly across genders, but in general, a 1.0 multiplier could be used for very little activity outside of the gym; 1.2 could represent moderate activity such as standing all day at your job; 1.4 could be used for a highly intensive job where you're moving all day long.
Now the fun begins.
On days you train, you can specifically estimate the amount of extra calories you utilize. The literature shows that typical resistance training burns roughly .048 calories per pound per minute spent training (3). This doesn't necessarily reflect rest periods, but time spent actually doing work.
So no, your 3 hour training marathon won't literally cost you hundreds of calories. You should actually be conservative in estimating your training time to reflect the actual amount of time you spend under the bar.
On top of all of this, we use a TEF multiplier to estimate the amount of calories you burn from your body utilizing the food you give it.
Here is what many people fail to realize: TEF can vary widely depending on the composition of your diet (4). A whole-food diet is going to give you the most bang for your buck here. Your body has a much easier time utilizing the energy from food that's already highly processed as opposed to how it deals with whole foods full of fiber and protein.
There’s also reason to believe whole foods can stimulate protein synthesis more effectively than processed foods (5).
This TEF multiplier can range from 1.10, reflecting poor nutrient partitioning thanks to a highly-processed diet, all the way up to 1.25. In the context of a 1000 calorie meal, that can be the difference of nearly 150 calories. Over time, that can be the difference from staying “fluffy” or having the physique of your dreams.
You can also take a more practical approach by tracking your calorie intake and scale weight to see what level of intake keeps you at the same weight over time. However, unless you have a method of tracking body composition, this method may not paint a complete picture.
For this reason, I recommend combining these approaches: use the calculations to set a baseline, and tinker from there to see what keeps your weight & body composition stable. I spend an initial period with all of my clients utilizing a similar protocol in order to set a specific baseline on an individual level.
After finding this level of intake, you can apply an energy deficit or surplus to push you toward your goal. By now, you should see how much of an art form constructing an effective diet truly is. And we're just scratching the surface.
Lucky for you, I've created a Macro Calculator that will streamline part of this process & give you an estimate of your daily maintenance calories & much more. Click here to download.
If you want to take things a step further and set up an optimal diet & training program based on your specific context, check out my coaching offerings.
Enjoy the content? Check out my other blog posts, and be sure to look into the Bayesian Bodybuilding PT Course. I’ve learned more about health & fitness in less than 12 months in that course than I have in the last 12 years of my life combined, including information just like this.
(3) Applied Nutrition & Human Metabolism Edition 6, Page 293
The techniques, strategies, and suggestions expressed in this website are intended to be used for educational and entertainment purposes only. The author is not rendering medical advice of any kind, nor is this website intended to replace medical advice, nor to diagnose, prescribe or treat any disease, condition, illness or injury.