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

A 2026 systematic review and meta-analysis of 20 randomised controlled trials covering 15,782 participants (Eisa N, Barood O. Lean Mass Changes With Incretin Therapy Versus Lifestyle Intervention. Diabetes, Obesity and Metabolism. 2026;28(6):4818-4827) found that 25 to 39 percent of the weight lost on incretin medications is fat-free mass. The share depends on the medication: 35.2 percent on semaglutide (95% CI 31.5 to 38.9), 26.8 percent on liraglutide (23.1 to 30.5) and 25.4 percent on tirzepatide (22.8 to 28.0).*

The most useful finding in that paper is the comparison. Lifestyle intervention without any medication came in at 26.2 percent (24.1 to 28.3), and the authors found no significant difference in the proportion of weight lost as lean mass between incretin therapy and lifestyle intervention. Lifestyle intervention combined with resistance training was lowest, at 17.5 percent (14.2 to 20.8). Read plainly: the medication is not doing something unusual to your body. Substantial weight loss is, however it is achieved. The lowest proportion in the analysis was reported in lifestyle interventions that included resistance training. That is a comparison between intervention groups rather than a direct test of resistance training, so we read it as reinforcing why resistance movement belongs in the picture rather than as proof that it is the deciding factor.

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 a comparable ratio, which points the same way.

The medication changes the number

That spread is worth knowing. Semaglutide is sold as Ozempic and Wegovy. Tirzepatide is sold as Mounjaro and Zepbound. Someone losing weight on semaglutide is losing roughly a third of it as fat-free 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 distinction matters throughout this page: fat-free mass is not the same thing as muscle. Fat-free mass measured by DXA includes water, glycogen and connective tissue, so a figure of 35 percent is not 35 percent skeletal muscle. Reported figures across the literature also run from 20 to 50 percent, in line with what is seen in diet-induced weight loss and after bariatric surgery.

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.
Ozempic® and Wegovy® are registered trademarks of Novo Nordisk A/S. Mounjaro® and Zepbound® are registered trademarks of Eli Lilly and Company. References to these names on this page are for informational and descriptive purposes only and do not imply affiliation, sponsorship, or endorsement by, or partnership with, Novo Nordisk A/S, Eli Lilly and Company, or any other GLP-1 medication manufacturer.