Any weight loss includes some loss of lean tissue, which includes muscle. This matters more when weight comes off quickly, as it often does with GLP-1 medications.
Strength training, enough protein and regular body composition checks can help make sure most of the weight you lose is fat.
Muscle helps the body manage blood sugar, supports the joints and helps with balance. It also uses more energy at rest than fat does, so maintaining muscle makes it easier to maintain weight loss.
In STEP 1, the main clinical trial of semaglutide for weight loss, a group of participants had body composition scans before and after 68 weeks of treatment. On average, fat mass dropped by about 19% and lean mass dropped by about 10%.
Because fat loss was much larger than lean mass loss, lean mass made up a larger share of body weight at the end of the study, an increase of about 3 percentage points. Lean mass on these scans also includes water and organ tissue, so not all of that 10% was muscle.
Muscle loss during GLP-1 treatment is real, but it can be managed. The steps below help.
Exercise also improves the overall results of GLP-1 treatment. Read more in why exercise matters when you take a GLP-1 medication.
Our weight loss program uses the InBody 580, a medical-grade analyzer that measures fat, muscle and body water. We scan at the start of the program and at follow-up visits so you and your provider can see whether your plan is preserving muscle. Learn more about progress monitoring and fitness guidance, or call (281) 466-4644 to schedule a consultation in The Woodlands or Katy.
The STEP 1 trial was funded by Novo Nordisk.
Some lean tissue loss happens with any weight loss. In the main semaglutide trial, participants lost much more fat than lean mass, so lean mass made up a larger share of their body weight afterward. Strength training and enough protein help limit muscle loss.
Strength train at least twice a week, include protein at every meal, stay active daily and track body composition instead of relying on the scale alone.
It depends on your body size, health and activity level. Your provider can help you set a target.
A regular scale cannot tell the difference. A body composition scan, such as the InBody 580 used in our weight loss program, measures fat, muscle and body water separately.
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This page is for general information and is not medical advice. Please talk with a provider about your own health. If you have a medical emergency, call 911.
