InBody Numbers to Track on a GLP-1 Medication

If you are losing weight on a GLP-1 medication, the InBody numbers worth tracking are skeletal muscle mass, body fat mass, the extracellular to total body water ratio and the visceral fat level, and the medication itself, its dose and its side effects stay entirely with your prescriber. A coach’s role begins only after your prescriber has cleared you to train, and it is narrow: read those four numbers every four to six weeks, keep the muscle line flat while the fat line falls, and hand anything that looks medical straight back to your clinical team. At FlexWerk in Carmel the baseline scan is free at the free consultation, and the whole report is walked through in the InBody scan explained pillar; this page covers only which lines matter during medicated weight loss.

The four lines, and what a good trend looks like

Skeletal muscle mass is the number to defend. During rapid loss the body sheds lean tissue alongside fat unless it gets a reason not to, so the target on a GLP-1 is a muscle line that holds within a pound or two across scans while body fat mass drops steadily. Percent body fat summarizes both, but the two mass figures tell you what the loss is made of, which is the whole question on this medication.

The ECW to TBW ratio, the share of your body water sitting outside your cells, is commonly read as balanced near 0.36 to 0.39 in the manufacturer’s education materials. Appetite suppression tends to quiet thirst as well as hunger, so a ratio drifting upward across scans is often the first sign that fluid intake has slipped. It is a flag for a conversation, never a diagnosis.

The visceral fat level, reported from 1 to 20 with 10 and above flagged as high, is the number most people on these medications are happiest to watch fall. Bring it to your prescriber’s appointments; what it means for your health specifically is their call.

Questions to ask your prescriber first

Before a coach programs anything around these numbers, get these answered by the person managing the medication:

• Are there activity limits I should train inside right now, and do they change when my dose changes?
• How much fluid should I be taking in daily, and is there any reason to be careful with electrolytes?
• Is there a protein target you want me to hold, or should a registered dietitian set it?
• Which symptoms mean I should stop a session and call you rather than push through?
• Would you like to see my InBody printouts, and how often?

Coaches do not answer any of those. They program around the answers.

What moves the numbers on this medication

Three things move the muscle line: whether you lift, whether you eat enough protein and whether you recover. Progressive resistance training two or three times a week is the signal that tells a body in a steep deficit to keep its lean tissue, and the coaching version of that plan is laid out in muscle retention training on a GLP-1. Protein is the raw material, and the protein target page covers the numbers. Recovery is the part people skip, and on reduced energy it matters more, not less.

Two numbers will move even when you do everything right, and both are worth expecting in advance. Basal metabolic rate is largely a function of lean mass and body size, so it drifts down as you get smaller; that is arithmetic, not failure. And the phase angle, which typically sits around 5 to 7 degrees in healthy adults and reflects cell health and muscle, can dip during fast loss. A stable or rising phase angle alongside a held muscle line is a reassuring pair; a falling one is another data point for your prescriber, not a reason to change anything about your own dose.

How a coach uses the printout

At FlexWerk, the printout sets the training block. Muscle held and fat down means the plan stays as it is. Muscle sliding across two matched scans means more protein-first meals, an added lifting day or a lighter deload, decided with you rather than guessed. A rising water ratio means a fluid conversation and, if it persists, a note to your prescriber. Scans run on the same machine as your baseline under similar conditions, ideally in the morning before food, which keeps the comparison honest, and the GLP-1 personal training page explains how the coaching relationship sits beside your medical care rather than inside it.

With oral GLP-1 options now on the market alongside the injectables, more people are starting these medications in 2026 without a plan for what the weight loss will be made of. A free scan before the next dose change is the cheapest way to get one.