InBody Scan Two: Same Weight, Different Body

🤖 Apollo (AI): the two scans, side by side

The scale hid the change. Between March 4 and September 22, 202 days, your weight moved 0.6 lb. Everything under it moved.

	Mar 4, 2026	Sep 22, 2026	Change
Weight	187.5 lb	186.9 lb	−0.6
Body fat mass	43.5 lb	40.1 lb	−3.4
Percent body fat	23.2 %	21.4 %	−1.8 pts
Skeletal muscle mass	82.0 lb	83.8 lb	+1.8
Fat-free mass	144.0 lb	146.8 lb	+2.8
Dry lean mass	38.6 lb	39.2 lb	+0.6
Total body water	105.4 lb	107.6 lb	+2.2
Visceral fat area	88.2 cm²	79.1 cm²	−9.1
Basal metabolic rate	1,782 kcal	1,810 kcal	+28
Fat-free mass index	20.7	21.1	+0.4
Phase angle	6.7°	6.6°	−0.1
ECW / TBW	0.371	0.372	+0.001
BMI	26.9	26.8	−0.1

By limb.

Segment	Lean, Mar → Sep	Lean % of ideal	Fat, Mar → Sep
Right arm	8.40 → 8.40 lb	108.7 → 108.7	2.4 → 2.2 lb
Left arm	8.18 → 8.16 lb	105.8 → 105.6	2.6 → 2.2 lb
Trunk	64.0 → 63.8 lb	103.9 → 103.6	24.3 → 21.8 lb
Right leg	21.16 → 21.80 lb	98.5 → 101.6	5.7 → 5.5 lb
Left leg	21.30 → 22.02 lb	99.1 → 102.6	5.7 → 5.5 lb

What the numbers show, directly. Fat mass down 3.4 lb, of which 2.5 lb came off the trunk. Skeletal muscle up 1.8 lb, and the segmental table says where: both legs gained about two-thirds of a pound of lean each and crossed from just under the ideal-weight standard to just over it. Arms and trunk lean are unchanged. Visceral fat area fell 9 cm², from 88 to 79, both under the 100 cm² line InBody treats as the threshold of concern. Resting metabolism is up 28 kcal a day, which is what an extra 2.8 lb of lean tissue costs to maintain. Water is up 2.2 lb, split evenly between inside and outside the cells, with the ECW/TBW ratio flat at 0.372, so the extra water is tissue, not swelling.

How much of that is real. Bioimpedance has a repeat-scan error of roughly 1.5 to 2 points of body fat and 1 to 2 lb on any single mass, even under matched conditions. Any one line in the table is inside that band. The reason to believe the picture is that six independent lines point the same way: fat mass, percent fat, visceral fat, skeletal muscle, fat-free mass, and BMR all moved in the direction six months of endurance training predicts, and the legs, which do the training, are where the lean went. The direction is signal. The exact size of each number is not.

Conditions were close to matched. Both scans were fasted, both in the morning. One difference to note: the September report is stamped 9:29 AM, an hour and a quarter before your swim started. If the scan actually happened after the swim, the device clock is wrong and mild post-swim dehydration would have biased body fat slightly upward, meaning the fat loss is, if anything, understated. Confidence in the direction of every change: moderate to high. Confidence in the magnitudes: moderate.

What did not move. Phase angle, 6.7 to 6.6, is flat and typical for age 51; it tracks cell integrity and changes slowly. Arm lean is identical to the pound, which is what you would expect from a program with no upper-body work to speak of. The pushups and swimming have not yet registered there.

🤖 Apollo (AI): what this does to the race-weight target

The 168 lb target is the wrong number, and this scan is why. It was set as a scale weight. With 146.8 lb of fat-free mass, reaching 168 without losing any of it means 12.6 percent body fat. That is a lean-collegiate-athlete figure, and at 51, on this training load, the realistic way to get there would be to give up muscle, which is the opposite of what the last six months accomplished and the wrong trade for a 70.3.

Target weight	Implied body fat, lean held	Fat to lose	Read
168 lb	12.6 %	18.9 lb	requires losing lean mass
172 lb	14.7 %	14.9 lb	aggressive, lean-athlete range
175 lb	16.1 %	11.9 lb	fit-athlete range, achievable
180 lb	18.4 %	6.9 lb	modest change from today

InBody’s own fat-control figure says 14.1 lb of fat to shed, which lands at 172.8 lb and about 15 percent. The last 202 days removed 3.4 lb of fat, or 0.12 lb a week, at a diet that was logged on fewer than half of the days and averaged about 100 g of protein. The race is 242 days out. At the same rate that is another 4 lb of fat, to roughly 183 at 19 percent. Reaching the low 170s needs the fat-loss rate to roughly triple, which is a nutrition problem, not a training one, and the two levers are the ones the weekly plans keep naming: protein at 135 g or more every day to protect the lean you gained, and a modest deficit on rest days only.

Recommendation. Change the race-weight target from 168 to 175, with 172 as the stretch, and measure progress by fat mass on the next scan rather than by the scale. The readiness model on the dashboard uses the target, so this is a one-line change once you agree. Book the third scan for mid-December, fasted, same time of day, before any training.

The new dashboard page. The full comparison, segmental tables, and the race-weight arithmetic are on the dashboard’s body composition page, fed from the InBody rows in the database, so the third scan will slot in without any of this being rewritten.