GLP-1 Resource Center

Why am I losing muscle on GLP-1 medications, and what to do about it

Lean mass loss during GLP-1 treatment is not a side effect in the traditional sense. It is a predictable consequence of significant caloric restriction that is not commonly discussed with patients before they start treatment.

The evidence

Across GLP-1 trials the share of weight lost as lean mass depends on the medication: about 26 percent on tirzepatide, and up to 45 percent on semaglutide, with a class-wide average near 30 percent and reported figures ranging from 20 to 50 percent.*

The SURMOUNT-1 DXA substudy, published by Look and colleagues in Diabetes, Obesity and Metabolism in 2025, enrolled 255 participants and analysed 160. On tirzepatide, 74 percent of the weight reduction came from fat mass and 26 percent from lean mass. The placebo group lost the same ratio, 75 percent fat against 25 percent lean, so this is weight loss behaving as weight loss rather than the medication doing something unusual. A 2026 systematic review and meta-analysis in the International Journal of Obesity, covering seven studies and 821 patients, put the class-wide figure near 30 percent, with liraglutide between 14 and 22 percent, tirzepatide around 26 percent and semaglutide as high as 45 percent.

The medication changes the number

That spread is the most useful thing this page can tell you. Semaglutide is sold as Ozempic and Wegovy. Tirzepatide is sold as Mounjaro and Zepbound. Someone losing weight on semaglutide may be losing close to half of it as lean mass, while someone on tirzepatide is nearer a quarter. Same direction of travel, different scale, and the figure that applies to you depends on which medication you are taking.

This is context, not a warning. It is not a reason to change or question a prescription, which is a conversation for the clinician who wrote it. What it does change is how much attention protein intake and resistance movement are worth during treatment, and that attention is free.

One caveat is worth holding onto: fat-free mass measured by DXA includes water, glycogen and connective tissue, so it is not skeletal muscle alone. And reported figures across the literature run from 20 to 50 percent, which is in line with what is seen in diet-induced weight loss and after bariatric surgery. A similar ratio appears in people losing weight without medication at all.

Why it happens

When the body is in a significant caloric deficit, it does not draw on fat exclusively. It uses all available energy sources, including lean tissue. Adequate protein intake and physical activity are the levers with the strongest evidence for shifting that balance.

The consequences extend beyond aesthetics. Lean mass is metabolically active tissue that supports resting energy use, strength and physical function, and it contributes to the fatigue and weakness many GLP-1 patients experience when it declines. Researchers also discuss lean mass as one factor in how the body responds after stopping medication, though weight regain has several drivers.

What the evidence supports

Protein intake. Most guidelines recommend 1.0 to 1.2g of protein per kilogram of body weight daily during active weight loss, and a 2026 review recommends 1.2 to 1.5g. For a 75kg person, that is roughly 75 to 110g daily. On a suppressed appetite, reaching that target through food alone is difficult for most GLP-1 patients. See how to get enough protein on Ozempic for practical strategies.

Creatine monohydrate. Creatine at 5,000mg daily has been studied extensively and has a long safety record. The condition attached to that evidence matters. A June 2026 meta-analysis in JISSN of seven randomised trials across 608 postmenopausal women found lean mass higher by 0.37kg and leg press strength by 7.5kg, but only at 5g or more daily taken alongside resistance movement. At 3g or less, or without resistance movement, no effect was found. Bone mineral density was unchanged. Creatine does not hold onto lean mass on its own. We say so plainly in the research behind TAKE Build.

Resistance movement. Movement during GLP-1 treatment, particularly resistance activity two to three times per week, is associated with a smaller proportion of weight lost coming from lean mass. Of everything discussed here, it carries the most evidence.

The connection to body composition outcomes

Attending to lean mass during GLP-1 treatment is associated with better body composition and with maintained strength and physical function. It is not only about appearance. It shapes what your body is made of when the weight loss is done.

The TAKE approach

TAKE Build provides 5,000mg of creatine monohydrate per 10g serving with sodium 1,000mg, potassium 200mg and magnesium 60mg. It is formulated to be taken alongside resistance movement, which is the condition under which the creatine evidence holds.* TAKE Nourish provides 21g of plant protein per serving in Chocolate and 20g per serving in Vanilla. Both products sit within The Strength System.

These statements have not been evaluated by the Food and Drug Administration. TAKE products are not intended to diagnose, treat, cure, or prevent any disease. Individual results vary. Always speak with your healthcare provider about medication side effects or medical concerns.