GLP-1 Treatment and Exercise: Why Strength Training Can Matter

Weight loss usually involves changes in both fat mass and lean mass. Lean mass includes muscle along with other non-fat tissues such as organs and body water, and how much is lost varies by person, study and treatment. That's one reason clinicians and researchers look at nutrition, physical activity and physical function alongside the number on the scale.

What the research shows about lean mass

A 2026 meta-analysis pooled 20 randomized trials (15,782 participants) that measured body composition with DXA or MRI scans. With semaglutide, tirzepatide or liraglutide, lean mass made up roughly a quarter to just over a third of the total weight lost (about 35% with semaglutide, 25% with tirzepatide and 27% with liraglutide). That proportion was broadly similar to weight loss from lifestyle programs alone (about 26%). In trials where lifestyle programs included resistance training, the share was lower, around 18%.

Those resistance-training results came from lifestyle trials, not from studies combining exercise with GLP-1 medicines, so they can't tell us exactly how much strength work protects muscle during GLP-1 treatment. Still, they fit the broader idea that how you lose weight matters, not just how much. (More on this in hair loss and muscle loss on GLP-1s.)

Why strength work may be useful

Resistance exercise—using bands, weights, machines or your own body weight—can help build or preserve muscle when it's appropriately designed and performed, and it may make everyday activities easier. It doesn't guarantee that no lean mass will be lost, and it's not the right starting point at the same intensity for everyone. Health conditions, joint pain, balance, prior activity and current energy levels should all shape a plan.

Nourishment matters, too

When appetite drops, some people find it harder to eat enough or get a varied diet. Adequate protein and overall nutrition support muscle maintenance, but individual needs differ, especially for people with kidney disease or other conditions. Be wary of extreme protein targets from social media. A dietitian or clinician can help if your intake is low or eating feels difficult. For ideas, see high-protein meals that taste good.

Start from your current ability

If you've been inactive, feel dizzy or weak, have heart or joint conditions, or are dealing with significant side effects, ask a healthcare professional how to begin safely. Gentle walking, chair-based movements or supervised resistance exercise may suit some people, but there's no single routine that fits everyone.

Measure function, not punishment

Notice whether everyday tasks get easier, whether you're getting stronger, and how you recover. In the company-funded STEP 1–4 trials of semaglutide 2.4 mg, more participants on semaglutide than on placebo reported meaningful improvements in physical functioning over 68 weeks—a reminder that function is worth tracking too. Exercise shouldn't be a punishment for eating or a way to force faster loss. If you get chest pain, faint, become severely short of breath or have another sudden symptom during activity, stop and seek medical care.

The goal is to support health, function and muscle as your body changes—not to turn workouts into another source of pressure. Make the plan realistic enough to repeat, and adjust it with qualified guidance when needed.