I mentioned on Sunday that my Lumen arrived, and that when I originally bought it, it was supposed to tell me my daily resting/basil metabolic rate through breath analysis. There are lab-level machines that can do this in doctor’s offices and such, and the original promise of Lumen was to be able to do this daily from the comfort of your home, rather than trying to get insurance to approve and/or paying exorbitant amounts for said test. This has not turned out to be the case in the final Lumen product, but it’s obvious that RMR/BMR has been on my mind quite a bit lately. This was compounded on Saturday while out with my hiking group.
At one point during our hiking, a few of the women in the group began to talk about their tested RMRs. These women were mostly older, 50s and 60s, and had been through many types of procedures in their lives. They’d also been chronic dieters on programs such as weight watchers, that encourage women to eat these very low calorie levels. (The current modern-day standard for weight loss programs for women is 1200, but the first time I tried WW in 2001, my calories were adding up to a range of 900-1150, and who knows what other levels it’s asked women to eat at over time! Even 1200 is NOT GOOD for most bodies.) These women began comparing their RMRs as tested by their doctors through various methods including breath-analysis and different kinds of body composition analysis. The results they gave ranged between 900 and 1100.
I was astonished to hear those numbers. To give some context, your RMR is the number of calories you burn at rest, if you did nothing but sleep for 24 hours. No one actually burns as few as their RMR, but it’s essentially how much your muscles, organs, and tissues burn at rest. The rest of your metabolism is built on that number. I’ve had body composition analysis done six times between 2012 and 2019, five of which gave me an estimated RMR. My weight on those tests ranged from 159 to 230. I kept the results of four of those tests, and from lowest weight to highest, on two electronic and two water-weigh tests, my RMR measures at 1636 (water, 159 lbs), 1447 (electronic, 164 lbs), 1552 (electronic, 204 lbs), and 1722 (water, 230 lbs). [Note: water weigh tests are more accurate than electronic ones.] My body’s burn range has been from 1447 to 1722 at 100% rest. Actual calorie burn measures roughly 500-700 calories higher, PLUS exercise on top of that. And frankly, I thought some of my RMR levels were pretty poor/low. I can’t even imagine the whole 900-1100 at rest range…
I don’t know how much of that is due to age and muscle loss, or chronic dieting causing muscle loss rather than fat loss, or some other factor. All I know is that I see the difference between my 40-year-old metabolism and the metabolisms of the 50s/60s women in my hiking group, and it makes me want to work especially hard to build and keep muscle mass as I get older. Regardless of any weight loss or change over time, I want to keep both my bone mass and my muscle mass strong and healthy. Other than yoga, I haven’t paid as much attention to strength-building as I should. I hope to slowly build that into my routine going forward. I want to be one of those 80-year-old women who still have the muscles of a 30-year-old!