Strength training on a GLP-1 medication

Short answer

When you lose weight, part of what you lose is lean mass, which includes muscle. In trials of GLP-1-based medicines, lean mass made up about a quarter to a third of the weight lost, a similar share to weight loss from diet and lifestyle changes. Programmes that added strength training lost a smaller share. Training two or three times a week, with enough protein, helps you keep your strength.

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What happens to muscle when you lose weight

Any large weight loss includes some lean mass. Lean mass is everything that isn’t fat: muscle, but also water, organs and bone. A 2026 review of 20 randomised trials found that lean mass made up about 25% to 39% of the weight lost with GLP-1-based medicines, and about 26% with diet and lifestyle programmes alone.^[1]

So the share is broadly similar however you lose weight. Some researchers think the concern is often overstated, because people usually lose a smaller share of their muscle than of their fat, and physical function tends to improve.^[2] It matters more if you’re older, or if you had little muscle to begin with.

What strength training changes

In the same review, programmes that added strength training lost a smaller share of lean mass, about 17.5% of the weight lost.^[1] In older adults with obesity who cut calories, strength training three times a week prevented most of the lean mass they would otherwise have lost.^[3]

Protein matters too, but it isn’t enough on its own. The joint advisory on nutrition with GLP-1 therapy says that eating more protein without structured strength training is unlikely to keep muscle.^[4]

How much training helps

The World Health Organization recommends muscle-strengthening activities that work all the major muscle groups on at least two days a week.^[5]
For people taking GLP-1 medications, the joint advisory suggests strength training at least three times a week, plus at least 150 minutes of moderate aerobic activity, adjusted to your fitness.^[4]

Start with what you can manage. Two short sessions a week is a good beginning. Read: how often to strength train, and for how long

What counts as strength training

Anything that makes your muscles work against resistance: dumbbells, machines, resistance bands, or your own body weight. Sit-to-stands from a chair, wall push-ups, rows with a band and glute bridges are all good first moves.

Before you start

Check with a clinician first if you have a heart condition, a recent injury, or are 65 or over and new to exercise.

Get help now if you can't keep food or fluids down, have severe stomach pain, or feel faint. Contact your prescriber or urgent care today.

Frequently asked

Is walking enough?

Walking is good for your heart and mood, but it does less to keep muscle than strength training. The joint advisory on nutrition with GLP-1 therapy recommends both, with strength exercises on most weeks.

I've never lifted weights. Is it safe to start?

For most adults, yes, with light weights, simple movements and slow progress. If you have a heart condition, a recent injury, or are 65 or over and new to exercise, check with a clinician before you start.

Do I need a gym?

No. Bodyweight moves, resistance bands and a pair of dumbbells at home can work every major muscle group.

Why does strength training matter on a GLP-1 medication?