Wednesday, July 03, 2019

Glance under the hood

Beat and I are in Berlin, Germany, for his dad’s 80th birthday. It’s been a whirlwind week with lots of family time and less outdoor activity, so it seems a good time to post about the DEXA Scan I had on June 28.

Several weeks ago, I received an offer for a free scan in exchange for writing about the experience on my blog. I receive dozens of freebie offers on an annual basis, and usually ignore them because this isn’t a gear blog, and although I don't care to limit the content here, reviews rarely seem worth the effort. But I am a sucker for data … and it seemed like this data could be useful for planning my strength training for upcoming winter ambitions. So I signed up.

DEXA is an acronym for dual-energy X-ray absorptiometry. In a nutshell, this scan uses low-energy X-ray beams to measure body mass — parsing out lean mass, body fat, and bone. Most often these scans are used to measure bone mineral density, often in older folks with higher risk for fractures and osteoporosis. In recent years, DEXA has become more popular among athletes as one of the most accurate ways to measure body fat and predict muscle mass. I had my scan done at an office in Denver called Body Fat USA. It’s quick and painless — you just lie down on a table for six minutes, and then a technician spends another 20 minutes going over the results. The explanations only scratch the surface of the data, so if you don’t do much research before (as I hadn’t), you may walk away a little confused. However, it’s nice to have the data in hand for subsequent research.

I looked forward to learning my bone mineral density, as I carry several risk factors for early-onset osteoporosis — white woman with hyperthyroidism. So I had some concerns, but the news was good. My number landed me in the 91st percentile for women my age. Perhaps this is the reason why I can take so many hard falls but have yet to break a bone, besides toes. Typically people aren’t scanned for bone density until they have a problem, and by then there’s no way of knowing how much they’ve deteriorated from normal. I think this will prove to be useful baseline data to have on record as I grow older.

The most controversial information from DEXA Scan is body fat. It’s controversial because while DEXA is considered the most accurate test there is, it still has an error rate around 5 percent. It also measures all body fat, including hidden sources such as intramusclar fat and brain tissue, so the numbers read higher than your typical caliper test. I wasn’t expecting a great result, but it did prove discouraging — 29 percent. Discouraging, but not surprising. For much of my adult life, my weight sat near 135 pounds. Then, like many people with Graves Disease, I packed on weight after I started on anti-thyroid medication. In the past two years, I’ve been as high as 150 pounds — during “slumps” when I’m feeling less well, I also seem to skew heavier — and am currently sitting at 145.0. (Official DEXA scan weight. The scan also put me at 67.5 inches, which is a half inch taller than I thought I was.)

There was always hope that the weight was more muscle I was able to build once my thyroid hormone levels normalized, but now it’s clear that I’m carrying at least 10 pounds of fat I don’t really need. It’s also clear that not hauling that fat around will boost my long-range endurance. So, I should probably try to lose that weight. Grumble, grumble. I have historically been not great at dieting or restrictive eating, so I’m going to go the old-fashioned slow route of adding protein while cutting sugar and tracking calories through the rest of the summer, and then assess. (After we return from Germany. There's just too many delicious foods here. Look at me, I'm already making excuses.)

For me, the most interesting and useful part of the DEXA Scan was lean mass balance, which parses out the amount of muscle in each limb. Through the scan I learned I am carrying a full 1.1 pounds more muscle in my left leg versus my right — a severe imbalance that can lead to injury. My right leg is the one I injured during the Bryce 100, which I’ve been working to rehab since. However, I’ve also ramped up my cycling mileage, which allowed me to heavily favor my left leg in order to generate the power necessary to climb hills. Still, I wonder if I developed this imbalance in the short span of the six weeks I’ve been injured, or whether this is a problem I’ve had much longer. Such an imbalance could have indirectly led to my current injury — adductor strain and MCL tear. Either way, I now know I have work to do. One-legged squats, ugh. And I’ll be able to take this info to my physical therapist next week, to gain more insight from her.

Overall, the information from the DEXA Scan will be useful in planning my training for the next few months, and I’m glad I had this opportunity. The data is interesting enough that I will probably pay the $100 for another scan in six or seven months, to see whether I’ve moved toward improvements I hope to make.

To learn more about DEXA Scans, visit


  1. I in no way want to know my body fat. Just don't. But I suspect I have muscle imbalance so that part would be interesting. Alas, nothing like that here in the sticks.

  2. I'm with you Jill on European goodies - I thought I would try to lose about 10lbs in 3 mo while in Europe, since I walk about 100x more in Prague than in California. But the abundance of sweets (albeit so much less sweet than in the USA) is too tempting to me.
    On bone density, when my wife had bunyan surgeries few years ago (in her 50-ies), the surgeon has commented on how strong her foot bones were and attributed it to running. Cycling is known to have the opposite effects on bone density.

  3. I'm going to be doing a deep dive under the hood in the coming months (I like that annology, thanks!) age and metabolic changes are a pain in fat levels moving. "Time Restricted" eating helps some ,rather than cutting calories, and there are different ways to do it. Everyone has muscle imbalances, I think due mostly to the dominate limb always being used first( grabbing or stepping) single leg training has reduced my imbalance and improved my joint strength. My trainer, she had me doing "Single Leg Romanian Dumbell Dead Lifts"....was that a "holy bad balance batman" moment!! lol Took time but ankle stability really improved and balance followed. She is a big "form and core "focused and I have seen good improvement. My right knee stability and strength is a work in progress along with my right shoulder.

    Jeff C


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