Strength & muscle

How to keep muscle on a GLP-1

Last reviewed 2026-10-20 · By GLP1 Sidekick Editorial · 4 min read

The short answer

Some of the weight lost on any GLP-1 is lean mass: in the STEP 1 semaglutide trial, about 38% of the weight lost was lean tissue. The two main defenses are enough protein (higher targets of about 1.2–1.6 g per kg a day have been proposed during weight loss) and regular strength training—a 2025 expert advisory recommends at least three strength sessions a week plus 150 minutes of moderate aerobic activity.

This guide is educational and not medical advice. It does not give dosing instructions. Talk to your prescriber or pharmacist about your own situation.

Do you lose muscle on Ozempic, Wegovy or Zepbound?

Some, yes—as with any large weight loss. The 2025 joint advisory summarizes the data:

In STEP 1 (semaglutide), of an average 13.6 kg (about 30 lb) lost, 8.3 kg (62%) was fat and 5.3 kg (38%) was lean mass—muscle plus other non-fat tissue.
Since muscle is roughly half of lean mass, that’s about 20% of weight lost being muscle.
In SURMOUNT-1 (tirzepatide), total lean mass fell by 8.5 percentage points.
Modeling suggests muscle loss may be 10–15% of weight lost in women and 20–25% in men without structured strength training.

These losses are similar to other big weight-loss methods such as bariatric surgery, and are affected by how fast you lose weight, how much you cut calories, and whether you strength train.

Why does keeping muscle matter?

Muscle supports strength, balance, blood-sugar control and everyday function. The advisory notes higher risk of muscle loss (sarcopenia) with older age, menopause, lower testosterone, inactivity and low protein. Rapid, large weight loss can also affect bone density, which strength training helps protect.

How much protein do I need to protect muscle?

The standard adult recommendation is 0.8 g per kg of body weight a day; the advisory notes that 1.2–1.6 g/kg/day has been proposed during active weight loss, while acknowledging it’s unclear which body weight to base this on. Practically, aim for a protein source at every meal and snack—our 1-day plan shows one way to reach about 90 g. If you have kidney disease, ask your clinician first.

How much strength training should I do on a GLP-1?

Source	Recommendation
2025 joint advisory on GLP-1 therapy	Strength training at least 3 times a week plus at least 150 minutes of moderate aerobic exercise weekly, tailored to the person
CDC adult guidelines	At least 150 minutes of moderate activity a week plus muscle-strengthening activities on 2 or more days

Strength training doesn’t have to mean a barbell. Bodyweight moves (sit-to-stands, wall push-ups), resistance bands, machines and free weights all count. Start where you are and progress gradually; if you’re new to exercise or have health conditions, ask your clinician or a physical therapist for a starting plan.

How do I know if I’m keeping muscle?

Track strength: are you lifting a bit more, or doing more reps, over weeks?
Notice function: stairs, carrying groceries, getting up from a chair.
Body-composition scans (DEXA, bioimpedance devices like InBody) can estimate lean vs fat mass, though home devices vary in accuracy.
Tell your prescriber about unusual weakness or fatigue.

What does a simple starter strength routine look like?

A beginner session can be 20–30 minutes, two or three times a week, working the major muscle groups: legs (sit-to-stands or squats), pushing (wall or counter push-ups), pulling (band rows), hips (glute bridges) and core (planks or dead bugs). Many people start with 1–2 sets of 8–12 controlled repetitions and add reps, sets or resistance as it gets easier. Apps and programs in our strength training category can structure this for you. This is general fitness information; ask your clinician or a physical therapist if you have joint, heart or other health concerns.

Does protein timing matter?

Getting enough protein over the day matters most. Because GLP-1s make you full quickly, the JAMA Internal Medicine patient guide suggests starting meals with protein (about 20–30 g) so it isn’t crowded out. Spreading protein across meals also makes the daily total more achievable.

Who is at higher risk of losing muscle?

The joint advisory names older age, perimenopause or menopause, lower testosterone, sedentary behavior, not doing strength training, and low protein intake from reduced appetite. If any apply, it’s worth asking your prescriber about a referral to a registered dietitian, physical therapist or exercise physiologist.

What about bone health?

The advisory notes that weight loss that is substantial (14% or more) and rapid (over 3–4 months) is associated with significant bone loss, whereas more moderate, slower loss may better preserve bone. Strength training, enough protein and nutrients such as calcium and vitamin D support bone—ask your clinician whether you need supplements or a bone-density check.

Quick answers

How much of GLP-1 weight loss is muscle?

In the STEP 1 semaglutide trial, about 38% of weight lost was lean mass (muscle and other non-fat tissue); because muscle is about half of lean mass, roughly 20% of the weight lost was muscle, according to a 2025 joint advisory. Strength training and enough protein help limit this.

What is the best exercise to keep muscle on Zepbound or Wegovy?

Resistance (strength) training. The 2025 joint advisory recommends strength training at least three times a week plus 150 minutes of moderate aerobic activity, customized to you. Bodyweight exercises, bands, machines and weights all work.

Do I need protein powder to keep muscle on a GLP-1?

Not if you can reach your protein goal with food. Shakes or powders are a convenient backup when appetite is low.

Does walking count as strength training on a GLP-1?

Walking is great aerobic activity, but it isn’t muscle-strengthening. The CDC counts the two separately: at least 150 minutes of moderate activity like brisk walking each week, plus muscle-strengthening activities that work all major muscle groups on 2 or more days.