How to Train Clients on GLP-1s Without Letting Them Lose Muscle

In KFF’s latest polling, nearly 1 in 5 US adults say they’ve used a GLP-1 drug, and 12% are on one right now. If you train adults for a living, you already have GLP-1 clients, whether they’ve told you or not.

NASM’s 2026 trends report puts it plainly: these drugs have pushed the trainer’s job toward strength and muscle preservation, and away from burning calories. That’s not a threat to your business. It’s the best pitch you’ll ever get.

GLP-1s in 60 seconds

• What they are. Prescription drugs (you’ll hear Ozempic, Wegovy, Mounjaro and Zepbound) that act on fullness. Clients feel less hungry, eat less and lose weight.
• The rhythm. One shot a week, usually on the same day.
• The ramp-up. Treatment starts low and steps up gradually over several months.
• How clients feel. Fatigue and nausea are common, especially early on and whenever treatment changes.

Ask every GLP-1 client two questions at intake: what day is your shot, and when does your treatment change next. That’s all you need to plan your sessions.

The muscle problem, in real numbers

In the STEP 1 trial, participants lost about 15% of their body weight over 68 weeks. DXA scans showed that roughly 40% of the weight lost was lean mass.

Before you scare your clients with that number, two caveats:

• Lean mass isn’t all muscle. DXA also counts water and glycogen, so actual muscle loss is lower.
• Trial participants weren’t on a supervised strength program. That gap is exactly what you fill.

The mechanism is simple. Appetite drops, food intake drops with it, and without a training stimulus the body has little reason to hold on to muscle. For clients over 60, that’s not cosmetic: it’s strength, balance and independence.

Stay in your lane (it makes you more valuable)

You see this client more often than anyone on their care team. Use that, but stay within your scope of practice:

• No opinions on the medication. Every question about it goes to the prescriber.
• No meal plans. Nutrition targets belong to the physician or a registered dietitian (RD).
• Build the bridge. With the client’s permission, a short note to their provider (“I’m training them three times a week”) makes you the trainer they refer to.

The 3-phase training plan

Phase 1: ramp-up

Stick to big, easy-to-load patterns:

• goblet squat or leg press;
• dumbbell Romanian deadlift;
• bench press or dumbbell press;
• rows and pulldowns;
• split squats or step-ups;
• planks and carries.

Keep sessions under 45 minutes. The client should leave feeling they had more in the tank. Right now, the win is that they come back.

Phase 2: active loss

This is where muscle is most at risk, so strength needs to hold at the very least.

• Use double progression. Once the client hits the top of the rep range on every set, add load.
• Pick 3 or 4 benchmark lifts (squat, press, row, RDL) and keep them across blocks. They’re your early warning system.
• Treat cardio as a supplement. Walking, cycling or easy rowing. Skip the extra HIIT to “burn more”: recovery is already harder.

Phase 3: maintenance

In the STEP 1 extension, people who stopped treatment regained about two-thirds of the weight they’d lost within a year. The strength they built with you, and the habit of training, are their best insurance. Plan for this phase from day one: clients who actually enjoy lifting are the ones who keep their results.

Adjust each session

• The days right after the shot are often the roughest. Track your client’s pattern and schedule hard sessions away from them.
• When treatment changes, dial intensity down a notch.
• Run a 30-second check-in before you start: sleep, energy, motivation. Two bad answers means the lighter version of today’s session.
• Hydration: water within reach and longer rests when it’s hot.
• Slow transitions: getting up from the floor in two steps.

Nutrition: ask, don’t prescribe

In 2025, four US organizations (ACLM, ASN, the Obesity Medicine Association and The Obesity Society) published joint nutrition guidance for GLP-1 therapy. Adequate protein and resistance training are among their priorities for preserving lean mass. Specific targets are set by the physician or the RD.

Your part is one question every session: “How’s your eating going? Are you getting protein at most meals?” If the answer worries you, encourage the client to bring it up with their provider or an RD.

Track what actually matters

The scale can’t tell you what’s being lost. Track a few things:

Metric	How often	Why
Load and reps on 3 or 4 benchmark lifts	Every session	Your best gym-floor proxy for muscle
Waist, hips, thighs and arms	Every 2 to 4 weeks	Shows where the loss is coming from
Progress photos	Monthly, same conditions	Keeps clients motivated when the scale stalls
Sleep, energy, motivation	Every session	Adjusts today’s session
Body weight	Weekly, same day	One data point among others

The red-flag rule: if weight and benchmark strength drop for 2 or 3 sessions in a row, ease off and suggest the client check in with their provider.

The line to use with clients

The medication handles the scale. I handle your strength.

That framing changes everything. Clients stop coming to you to “lose weight” and start coming to stay strong. It’s also what earns you a place next to their medical care.

Turn it into a niche

GLP-1 clients are one of the fastest-growing groups walking into gyms, and most trainers still pitch them a generic weight-loss package. A few ways to stand out:

• Package it. A 12-week “strength first” program is easier to sell than open-ended sessions.
• Share progress. A one-page monthly summary (strength trend, measurements, attendance) that clients can show their provider gets you noticed and referred.
• Change your message. “Lose fat, keep your strength” speaks to these clients far better than “get shredded”.

Key takeaways

• The goal isn’t weight. It’s strength.
• Start with two sessions a week, move to three once treatment is stable.
• Go lighter right after the shot and whenever treatment changes.
• Strength on 3 or 4 benchmark lifts is your most useful metric.
• Medication and nutrition stay with the provider and the RD.

This article is for educational purposes and doesn’t replace advice from your client’s healthcare provider.

Sources

• Wilding et al., Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1), New England Journal of Medicine, 2021.
• Wilding et al., Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension, Diabetes, Obesity and Metabolism, 2022.
• Mozaffarian et al., Nutritional priorities to support GLP-1 therapy for obesity, Obesity, 2025.
• KFF, Health Tracking Poll: prescription drug costs and GLP-1 use.
• NASM, Top fitness trends.