What is BMR and Does It Matter?
Quick question…do you know your BMR? If you do know it, do you know if it’s accurate? In this post we’ll talk about what your BMR is, what it’s used for, why it’s important to have an accurate BMR, and what’s important beyond that fundamental number. First things first, what is BMR?
BMR stands for Basal Metabolic Rate
Your basal metabolic rate is the number of calories it takes to keep your body functioning. Your organs and vital body functions require energy to keep doing what they do – keep you alive. So, your BMR is a baseline caloric number. Think about Sleeping F-ing Beauty. She ate nothing for years and stayed perfectly healthy and kissable, right? Not likely, because she wasn’t eating anything and didn’t have calories to keep her heart pumping or her ovaries singing as they happily waited for Prince Charming.
Okay, so you get this BMR number and then what? What do you do with it? What is it good for?
How Do You Use Your BMR?
There are a few ways you can use your BMR. You can use it to:
Calculate Your Daily Caloric Intake
You know the drill. You need to burn more calories than you consume if you want to lose weight. That’s the theory anyway. So, a pound is 3500 calories and if you want to lose a pound a week, that means consuming 500 fewer calories than you burn (500 calories times 7 days is 3500 calories)
Using that example, let’s say that your BMR is 1200 and you go out and you run two miles every day and you are lightly active. You may end up with a daily calorie burn of around 1400-1500. To lose weight then, the common approach is to consume less than 1400-1500 calories. So, your BMR is one of the key components into determining how many calories you need to eat and burn to lose weight.
My two cents…I feel that while calories play a role, it’s more important to pay attention to WHAT you put into your body. A calorie from a Twinkie is vastly different than a calorie from green beans or whatever amazing vegetable you like.
Macros are macronutrients. We’re talking about the three basics: carbs, protein, and fat. Many people measure their macros to lose weight, to maintain weight, and to improve strength and endurance. For example, anyone who is ketogenic or low carb will want to keep a close eye on their carbs and protein. Protein is based on lean body mass, but carbs are often based on your BMR and physical activity.
My two cents again…macros can be manipulated. If you need more carbs, you could choose a piece of toast or an apple. Point being, a calorie is not a calorie and a macro is not a macro.
So, let’s talk about how to measure your BMR and where to get those numbers, because it matters.
Why Accuracy Matters
If you’re trying to lose weight or calculate your macros then it’s important to have an accurate caloric baseline. Imagine this. Imagine that you think your BMR is 1400 when it’s really 1200. So, every day you’re working hard you’re actually burning 200 calories less than you think you are so you’re not losing weight. It can be defeating. And if you’re counting macros to boost strength and endurance and your BMR is wrong, you may not be getting the nutrients you need to perform and recover optimally. It’s important to get a solid BMR.
How to Get A BMR
There are online calculations you can use to get your BMR. Just type BMR and Calculator into your browser and you’ll see pages of results. There are also mobile applications like Cronometer and MyFitnessPal that have BMR calculators.
Unfortunately, in my experience, these calculators can be off by a few hundred calories based on your personal body composition. BMR calculators just use your gender, age, height, and current weight to calculate your BMR. But they don’t know how much of your weight is muscle, fat, bone, and water. This matters. It requires much more energy to maintain muscle mass than fat. a 125-pound person who has 10% body fat will burn way more calories and have a higher BMR than a 125-pound person who has 20% body fat.
Body Composition Testing
You can also have your BMR measured through body composition testing. There are a number of different tests you can have. I’ve used Inbody 570 which uses bioelectrical impedance and essentially sends a current through your body. Some systems are better than others when it comes to this approach. There’s also DEXA scans and hydrostatic measurements. Any of these are more accurate than an online tool or a mobile app.
When it Comes to Body Fat and Body Composition Measurements, I have Some Thoughts…
I feel like it can be helpful to know what your BMR and body composition numbers are. If you like data and it motivates you, then this data can be helpful. However, I also feel like people can get caught up in the numbers and it can have a negative impact. You may get a body fat number that you don’t like and that makes you feel bad about yourself and your body. No Bueno! Or you may get a really low number and feel like a stud. Again, no Bueno.
We’re so much more than our body fat number and getting caught up and establishing our self-worth on that number makes me sad. Your body, regardless of you body composition, is beautiful and is keeping you alive.
What Data May Matter More (And Why)
When you have a body composition test done, not a BMR calculation, but an actual body composition, you can get information on visceral body fat. This is the fat that is around your organs. This fat is dangerous to your health. Visceral fat is a predictor of mortality – meaning those people with higher levels of visceral fat have an increased risk of death. (https://www.ncbi.nlm.nih.gov/pubmed/16571861).
It is associated with medical disorders such as metabolic syndrome, cardiovascular disease and several malignancies including prostate, breast and colorectal cancers, (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3473928/).
As you might imagine, knowing if you have a high percentage of this deadly type of fat, can give you valuable knowledge and motivate positive change.
If you feel you are at risk for having a high (and unhealthy) body fat percentage and you are looking to improve your health, then having a body composition test and knowing your body fat is a great starting point. You can use this data to evaluate your success as you improve your lifestyle through diet and exercise.
A word of caution, however…while getting your body fat to a healthy level is important, it is equally important to feel good about yourself, to have energy and vitality.
It’s also easy to get hung up on a number and you, my beautiful friend, are so much more than a number. Test if you want a baseline and you want to measure success. However, consider only testing once or twice a year. Pay attention to those other indicators of health like energy levels, improved sleep, better complexion, improved digestion, and of course more balanced moods and hormone levels.