A DEXA or InBody report hands over dozens of numbers, but only a handful matter, and the first week is for recording them rather than reacting to them.
A page full of numbers and nobody to read it
The scan itself is the easy part. You lie still on a padded table, or stand barefoot on a pair of metal footplates and grip two handles, and a few minutes later someone hands you a printout. Then the hard part starts. There are tables for arms, legs and trunk. There’s a line called PBF, another called BMR, sometimes an android to gynoid ratio, sometimes a visceral fat estimate with a bar graph next to it.
For a lot of adults over 40, the scan was booked for a sensible reason, maybe a doctor’s suggestion or a free InBody test at the gym. The report rarely comes with an explanation, though. So the paper goes home, gets stared at over coffee, and ends up in a drawer.
That’s a waste of a good baseline. Most of what’s on the page can be set aside for now. A few lines deserve a pen circle.
The five lines worth circling
Start with weight, which is simply what you weighed that morning. It’s the number you already know, and it tells you the least.
Next is lean mass: everything in your body that isn’t fat, including muscle, organs, bone and water. It’s the line most worth protecting after 40, and it drives most resting burn formulas. Body fat percentage is fat as a share of total weight, which is why it should always be read next to the fat mass line, the same fat expressed in pounds. Fat mass is often the clearest number to follow over time, because a flat scale weight can hide fat going down while lean mass goes up.
Last is resting rate, an estimate of what you burn at rest. On most reports it isn’t measured at all. It’s calculated from your lean mass using a published formula, so treat it as an informed estimate rather than a lab result.
The trick is finding these lines, since every machine labels them differently. On an InBody sheet, lean mass appears as Lean Body Mass near the top, and body fat percentage is PBF. A Bod Pod report calls lean mass Fat-Free Mass. FitNoggin, an education site built for adults over 40 who have a scan report but no plan, keeps a plain reference showing where each of those lines sits on a DEXA, InBody or Bod Pod report. One useful note from it: InBody also prints Skeletal Muscle Mass, a separate and smaller figure that represents the trainable part of your lean mass. Don’t confuse the two.
Why the machine across town will disagree with you
The three common scanners work in completely different ways. DEXA uses a low-dose x-ray. InBody sends a small electrical current through the body and estimates lean mass from water. Bod Pod measures how much air you displace to work out body density, then estimates body fat from that.
Each method carries its own error, so one person can come out a few points apart on two machines in the same week. The practical rule is blunt: compare a scanner only with itself. A DEXA result from one clinic and an InBody result from your gym aren’t a before and after. They’re two separate baselines.
Even on the same machine, conditions move the numbers. InBody readings swing most with hydration, and a salty dinner the night before can shift lean mass by a pound or two. DEXA and Bod Pod drift less, but a change of one to two pounds can still be test noise. FitNoggin’s free guide, Reading Your First Scan, walks through the five lines in plain words and is worth reading before you draw any conclusions from your first printout.
A first-week checklist that costs nothing
The week after a first scan isn’t the time to overhaul your diet. It’s the time to make sure the next scan will be comparable to this one.
Write down your baseline. Record the date, the time of day, the scanner and location, and the key lines: weight, lean mass, body fat percentage, fat mass and resting rate. Add a note on the conditions, such as whether you’d eaten and whether you’d trained hard the day before.
Pick a rescan date about 90 days out. A sooner rescan mostly picks up water and timing. When you book, aim for the same machine, the same time of day, similar food and drink beforehand, and light clothing with nothing in your pockets.
Plan a midpoint check around day 45 that doesn’t involve a scanner at all. That’s when you look at your lifts and your protein against what you intended to do. FitNoggin sells a guide built around exactly this structure, a 90-day plan from baseline to rescan, for anyone who wants the months laid out.
If anything on the report worries you, particularly a visceral fat estimate, take it to your doctor rather than a search engine. Every scanner estimates visceral fat differently. Check with your doctor, too, before any major change to how you eat or train.
What to leave alone for now
One scan is a baseline, not a verdict. The regional tables and ratios will mean more once a second report sits beside the first. Until then, the most useful thing you can do with that printout is copy five numbers into a notebook and put a rescan date on the calendar before the paper disappears into a drawer.
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