Will GLP-1 treatment make you lose muscle?
Updated: Oct 1
Weight loss is not all fat loss
When body weight falls, the change can include fat mass, lean tissue, glycogen and water. The exact composition depends on the person and how weight loss occurs. That is why focusing only on kilograms can miss an important part of health.
Are GLP-1 medicines uniquely causing muscle loss?
Some lean-mass reduction has been observed in body-composition substudies during GLP-1-associated weight loss. However, lean mass also falls during calorie restriction and other forms of significant weight loss.
The useful question is therefore not whether lean mass changes at all, but how much is preserved relative to the overall health benefit.
Protein matters
When appetite falls, some patients unintentionally reduce protein as well as total calories. A nutrition plan should make adequate protein intake deliberate rather than assuming it will happen automatically.
Individual protein needs can vary with body size, age, kidney function, activity and other health factors, so the final public article should avoid one universal gram target unless Medara's clinical team approves it.
Resistance training matters
Strength or resistance exercise provides a signal to maintain muscle and function during weight loss. It can also support mobility, bone health and longer-term metabolic health.
The program should be appropriate to the patient's baseline fitness and any medical limitations.
Measure success more intelligently
Depending on the service, useful indicators might include strength, physical function, waist circumference and body-composition measures alongside body weight.
The goal is a healthier body, not simply a lighter one.
References:
Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity. New England Journal of Medicine. 2021. PubMed
American Diabetes Association. Pharmacologic Treatment of Obesity in Adults: Standards of Care in Overweight and Obesity. 2026. DOI
WHO. Guidelines on Physical Activity and Sedentary Behaviour. Muscle-strengthening activity is recommended on 2 or more days per week for adults.
Written and clinically reviewed by: Dr Saran Seker, MBBS (Aus), Chief Medical Officer
Last reviewed: September 2026
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