You got the baseline scan, you did the work, and now the second report is in your hands — two columns of numbers that are supposed to tell you whether the last few months went the way you hoped. The trick is knowing which of those numbers actually moved, and which just wobbled.
If you haven't had your first scan yet, start with our companion guide on getting a DXA scan and what it measures. This one picks up afterward: how to read a report against your last one and tell real change from measurement noise.
The numbers that matter, and what "better" looks like
A DXA report hands you more figures than you need. The ones worth watching over time are:
- Total mass — your weight, the same number the scale gives you, and the least informative one here.
- Fat mass — total fat in kilograms or pounds, plus a breakdown by region (arms, legs, trunk). This is the number you most want to see fall.
- Lean mass (sometimes labeled lean soft tissue or fat-free mass) — muscle and everything else that isn't fat or bone. The number you most want to protect.
- Body fat percentage — fat mass divided by total mass. Useful, but it can move just because one of its two inputs moved, so read it alongside the raw kilograms, not instead of them.
- Visceral fat (VAT) — the metabolically active fat around your organs. Often the fastest-improving number early in GLP-1 treatment, but also the least precise one on the report (more on that below).
- Bone mineral density — carried over from DXA's original job as an osteoporosis screen. It changes slowly, so don't expect meaningful movement between scans a few months apart.
On a GLP-1, a good trajectory is straightforward to describe and harder to achieve: fat mass down, lean mass holding as steady as you can keep it. A drop in total weight that is almost entirely fat, with lean mass barely changed, is the outcome you're training and eating for. Falling lean mass alongside the fat is expected to some degree — but it's the signal to double down on protein and resistance work, not to celebrate the smaller number on the scale. (One caveat if you've lost a lot of weight: loose skin is fat-free tissue that DXA files under "lean," which can flatter that number — see )