Watching the number on the scale drop is satisfying. It is also incomplete. Two people can each lose 30 pounds on Ozempic, Wegovy, or Zepbound and end up in very different places. One lost mostly fat and kept their strength. The other lost a good deal of muscle along with it, feels weaker and more tired, and may have a harder time keeping the weight off later.
How much of GLP-1 weight loss is muscle?
Some loss of lean tissue comes with any significant weight loss. With GLP-1 medications the share may be higher. One clinical review puts it at an estimated 25 to 39 percent of the weight lost, compared with 10 to 30 percent when weight is lost through diet and exercise.
Two cautions apply. Lean tissue includes water and other tissue, not only muscle, and the estimates vary from study to study. Still, the pattern is consistent enough that a 2025 joint advisory from four obesity and nutrition organizations recommends checking muscle strength, function, and body composition as part of GLP-1 care.
Why the scale can't tell you
A scale adds fat, muscle, bone, and water into one number. BMI does the same thing with a height adjustment. Neither can say whether the five pounds you lost this month came from your waistline or from your legs and back.
Signs you may be losing muscle
- Everyday tasks feel harder, like climbing stairs, carrying groceries, or getting up from the floor
- Your grip or your strength during exercise is dropping
- You feel more fatigued than the weight loss alone would explain
- Your weight is falling very fast while you are eating little protein and doing no resistance exercise
None of these is proof on its own. That is why measuring helps.
What a body composition scan shows
Total Health Systems offers two options. InBody testing is 60 dollars and takes about 45 seconds. It reports body fat percentage, skeletal muscle mass, how muscle and fat are distributed across your body, and visceral fat levels.
BIA body composition analysis is 50 dollars and gives a quicker baseline: body fat percentage, fat free mass percentage, and how much water is held in your muscle versus under your skin. Both are non-invasive and involve no radiation.
A single scan is a starting point. Hydration, recent exercise, and a large meal can all shift a reading, so the real value is in the trend. Scan under similar conditions each time and compare.
At weeks 1, 2, 4, 6, 9, and 12, so your plan can be adjusted while it is still running.
What to do if a scan shows muscle loss
- Bring the results to your prescriber. The pace of weight loss and your dose are their call, and this is useful information for them.
- Put protein first at every meal. Our guide on what to eat on a GLP-1 covers how.
- Add strength training. Guidance points to at least three sessions a week. Protein without resistance work is unlikely to be enough.
- Rescan in a few weeks. One reading tells you where you are. Two tell you where you are going.
Get a baseline in Macomb County
If you are on a GLP-1 or about to start one, a baseline scan gives you something to measure against. For ongoing support, First Line Therapy pairs the scans with a personalized nutrition plan and regular check-ins.
This article is general education and is not medical advice. A body composition scan informs a plan but does not replace care from your prescribing provider.