BMR, TDEE, RMR, CIA, FBI, WTF. The world is full of acronyms. Sometimes I wonder what people do with all the extra time they save by abbreviating their words. I mean, why can’t we just type this sh*t out? All joking aside, the fitness and nutrition industry uses tons of acronyms. One of our goals as a fitness and nutrition company is to educate people. This includes discussing what all these acronyms mean and why they are essential.
Let’s start from the top.
Think of the human body as one large unit of energy. Every moment of every day, there are cellular transactions taking place within your body. An example would be your circulatory system transporting oxygenated blood and nutrients to your muscles, your internal organs, and your brain. The body then uses those nutrients and oxygen as energy. Your body carries out many physiological processes all of which require energy.
In other words, if you were to sit on your butt all day and do nothing, your body still uses energy to keep you alive. This is what we call RMR or BMR. They stand for “resting metabolic rate” and “basal metabolic rate” respectively. People often use these terms interchangeably, and they are mostly the same thing. The only difference is that BMR measurements are exact only when taken in a medical setting. This would include waking up from 8 hours of sleep in a darkened room and after 12 hours of fasting so that the digestive system is mostly inactive. Sounds depressing as sh*t, huh?
So why should you care?
Your RMR is good to know because it tells you how many calories your body burns simply by existing. However, there is more to consider when calculating your total daily calories expended. The amount of calories you burn on any given day is what we call TDEE, or “total daily energy expenditure.” TDEE is your RMR (which we discussed above) PLUS the calories you burn doing whatever it is you do in a day. This includes activities like exercising, washing your car, doing chores, or walking to the other end of your house so that your phone can mooch off the neighbor’s wifi. Your TDEE is vital to know because it gives you an estimate of the calories you need on a daily basis to maintain your current weight. From there you’ll have an idea of the calories you need in order to lose or gain weight.
Breaking down TDEE.
Most of your TDEE comes from your RMR, while a smaller percentage comes from the activities I mentioned, which is known as your NREE (non-resting energy expenditure). There are three constituents of your NREE: one is NEAT (non-exercise activity thermogenesis). This would be any activity not considered exercise. Another is the TEF (thermic effect of food). Yes, you expend energy consuming and using energy. It’s a cyclical process. Lastly, your EAT (exercise activity thermogenesis). I don’t think that one requires elaboration.
As you can see, because of the three components that comprise your TDEE, it should be quite apparent that your TDEE won’t be the same every day. Finding your TDEE is like looking through a wide scope at a moving target. You pretty much know where it’s at for the most part, but it never stays in the same place.
So now how do you calculate?
First, you’d have to start with your BMR. It’s pretty boring, but the formula looks like this:
Men: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) + 5
Women: BMR = (10 × weight in kg) + (6.25 × height in cm) – (5 × age in years) – 161
There are several formulas, but this one happens to be the Mifflin-St. Jeor equation. Once you’ve got your BMR calculated, you’re then able to calculate your TDEE:
Sedentary or lightly active: BMR x 1.53
Active or moderately active: BMR x 1.76
Vigorously active: BMR x 2.25
Again, these are formulas that are just going to give you an estimate. One of the downsides to calculating your BMR is that it does not take into account your body fat percentage or body composition. So two people of the same age, height, weight, and gender, but of different ratios of fat to muscle could get the same reading, but the leaner, more muscular person would require more calories, as muscle demands more calories than fat.
This can all seem a bit confusing sometimes, so that’s why we have our calculator which does the work for you.
Again, these equations give you estimates. If you are unsure about your results, or you’d like a second opinion from one of our staff members, we’d be happy to assist. Just send a join request to our Facebook group page and ask for a macro check.
Hope to see you in the group!