Basal metabolic rate is the amount of energy your body needs, in calories, to perform essential life-sustaining functions. If you lay in bed and did nothing all day, this is roughly the amount of calories used. Every heartbeat, each breath, and blink of the eyes requires energy. It’s pretty wild to consider all the metabolic functions simultaneously occurring inside you, even when you’re in a resting state. Your BMR is similar to a fingerprint in that each person’s will vary based on several factors, including age, body composition, activity level, and body composition, to name a few. I would venture to say there isn’t a ‘good’ BMR, but you can increase or decrease it based on your lifestyle and eating habits, which I’ll discuss later.
Why BMR Matters
Knowing your BMR enables you to tailor your diet and exercise routine to meet your goals, be they weight loss, weight maintenance, or weight gain. Remember, BMR is a measurement of energy used when at rest; it doesn’t take into account exercise or any normal movement that you do over the course of the day. The actual amount of calories burned in a typical day will be slightly higher than your BMR.
Major Factors That Influence BMR
Age: The older you get, the slower your BMR becomes. Unfortunately, you don’t have much control over this one but fear not. Resistance training is one way to slow the decrease by maintaining muscle mass.
Sex: Men tend to have a higher BMR due to having more muscle mass on average than women. Once again, resistance training and lean body mass are your friends here.
Genetics: Some people are just born with a higher BMR and will sustain it better over their lifetime than others. Blame or praise your parents, then lift some weights to increase your BMR. Noticing a trend yet?
Body composition: Muscle is more metabolically active than fat tissue. For example, if you have two men who both weigh 200 pounds, only one has 10% body fat, while the other has 20%. The man with 10% body fat will burn more calories at rest than his counterpart.
Physical activity level: If you’re stuck at a desk all day, you’re expending much less energy than a construction worker moving about all day. Extrapolate this over the course of months and years, and the difference in energy use will be monumental.
Sleep: Poor sleep causes all sorts of problems, one of which is throwing a wrench into your metabolism. Chronic sleep deprivation can lower your BMR while also increasing your appetite—a double whammy if there ever was one (1).
How To Measure BMR
Fortunately, getting an estimate of your BMR is easy, and there are two ways.
Use the online calculator here. Enter your information as accurately as possible to get the best estimate. And remember, it is an estimate. While it won’t be perfect, it will get you in the ballpark.
Option two is getting tested on a device called a calorimeter. The test itself is simple: you sit at rest and breathe normally into a mask connected to the calorimeter for roughly 10 to 15 minutes. By measuring the composition of the air of your exhalation, the device will give you a more accurate BMR measurement than an online calculator. These tests can usually be done in the $100 to $200 dollar range. Ideally, should you choose this route, be sure to consult with a registered dietician upon completion of the test. They can provide you with a thorough breakdown of your results and assist with planning your diet to suit your needs.
Resistance Training Vs. Cardio
Above, I noted how resistance training and having more muscle mass are surefire ways to increase BMR. While any exercise is good, if you’re only doing cardiovascular training, you’re missing out on the benefits of lifting weights. You should not cease cardio training but add resistance to your exercise regimen. More muscle mass isn’t just good for your BMR; you’ll get stronger and probably live longer (2).
Don’t Self Sabotage
Just as your BMR can increase, it can also go down. The most common method is when a person is attempting to lose weight via severe calorie restriction. In the short term, this will work. However, consistently depriving yourself of adequate caloric intake inevitably turns you into a hangry jerk, and no one wants to be around, which torpedoes your BMR in the process. If your body thinks it is starving, it will respond by decreasing the amount of calories used in a given day. This typically ends with the person gaining the original weight back, plus a few extra pounds. This is another reason to lift some heavy objects as part of your exercise routine, even if your primary goal is weight loss.
Knowing your BMR gives you a head start on your health and fitness goals, not just losing weight. Even though it will decrease as you age, practicing a healthy lifestyle can mitigate the decline.
Need help increasing your BMR? Then you’re in the right place. Message me to get started with online fitness training.
Jurado-Fasoli, L., Mochon-Benguigui, S., Castillo, M.J. et al. Association between sleep quality and time with energy metabolism in sedentary adults. Sci Rep 10, 4598 (2020). https://doi.org/10.1038/s41598-020-61493-2
Srikanthan P, Karlamangla AS. Muscle mass index as a predictor of longevity in older adults. Am J Med. 2014 Jun;127(6):547-53. doi: 10.1016/j.amjmed.2014.02.007. Epub 2014 Feb 18. PMID: 24561114; PMCID: PMC4035379.