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Using DEXA to Assess Progress on Fat/Muscle Changes
By sharing this data and my commentary, I hope to provide useful perspective for serious athletes, and for those seeking health and fitness. Having good data allows setting realistic goals based on one’s current condition.
If DEXA is not available (or too expensive), try the swimming pool: inhale as deeply as possible, hold breath and go completely limp. Observe just how the body floats. When lean, your author can barely float and the body is pointed straight up down with ~1 inch of head protruding (muscle plus relatively high bone density). The slighest exhalation means plummeting to the bottom of the pool. (Body density like that is a huge disadvange for long distance swimming!).
January 5, 2012 scan
+114 days after Sept 13 scan
This is mid-winter (the off-season). I put on some fat, lost some muscle and overall did reasonably well staving off more significant gains. Still, the hard work to lean-out makes it disappointing to put 6+ pounds of fat back on. It’s just my body’s inclination, and could also be seasonal, as I had a hard training load in November/December 2011.
Relative to the Sept 13 scan—
- Body fat increased to 11.7% from 7.9%, or 3 kilograms (6.6 pounds). Disappointing, and can really be felt on the climbs!
- Leg muscle mass decreased by 424g (~1 pound).
- Total muscle loss of 1.5 kilograms, about 3 pounds.
- Android fat (the internal bad stuff) has doubled, but is still very low, at about 1.5 pounds (625 grams).
- Other fat (mostly subcutaneous, the good stuff), has increased by about 5 pounds. This can be felt in stomach/leg/arm skin that no longer feels thin, but thicker and more substantial.
September 13, 2011 scan
+89 days after June 16 scan
This is 80 days after the June 16 scan. Training was ramped up substantially in August, with increased duration, intensity. I also increased my protein intake for recovery nutrition, which I believe played a role.
Relative to the June 16 scan—
- Body fat declined by 3.8 kg (8.5 pounds) from 10.6% to 7.9%, the 0th percentile.
- Leg muscle mass has increased by 1.77 kg (3.9 pounds), or nearly 2 pounds per leg. Wow!
- Android fat (the internal bad stuff) has declined to 3/4 pound (total!),which is almost nothing.
- The gynoid fat has also decreased, in short I carry nearly all my fat as subcutaneous, with about half of it in the legs, easily confirmed with a pinch of the fingers.
Relative to Jan 1, 2011 (estimate based on March 31 scan):
- Body fat down by 36 pounds (about 1 pound per week).
- Muscle mass up by at ~10 pounds.
June 16, 2011 scan +35 days after May 12 scan
This is 35 days after the May 12 scan.
In theory, muscle mass in the legs has actually declined slightly, but this hovers close to measurement error. The trunk area has gained 1.3kg of muscle mass.
Based on higher power output, I’m skeptical of muscle mass loss in the legs. However, highly intensive training in the first two weeks of June could have degraded muscle mass slightly. A future scan a month or two off could help resolve this question.
May 12, 2011 scan +42 days
This is 42 days after the March 31 scan.
The DEXA scan shows that:
- My legs gained 2190 grams of muscle— a kilogram of new muscle per leg (2.2 pounds).
- Body fat declined by 4926 grams, almost 5 kilograms, or 10.8 pounds of fat.
I award myself an A+: gaining muscle while losing fat is the holy grail of weight loss.
Note on arms and trunk— one issue with DEXA is that arms and trunk can be confused because they are in close proximity (overlap). So my guess is that some of the gain in the arms and loss from the trunk is simply overlap of arms/trunk either with this scan, or the prior one, or both. This issue does not occur with legs.
- I gained 637 grams (1.4 pounds) of muscle in my arms.
- I lost 2213 grams of muscle in my trunk, but also lost 3721 grams of fat in my trunk.
March 31, 2011 scan +0 reference
This is the early season 2011 reference scan.