GLP-1 medications like semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) work largely by turning down your appetite, so you eat less and lose weight. The catch: a big share of that weight can come from muscle, and when you're barely hungry it's hard to eat enough protein to keep it. Here's how to keep your muscle on a GLP-1, from a coach who has trained clients using them.
A GLP-1 is a tool. Your habits keep the results.
There's nothing wrong with using one of these medications to get an edge, under your doctor's care. They're prescription drugs, so be mindful of the side effects and work with your doctor.
But the medication is the tool, and your habits are what keep the results. If you ever stop or switch medications, you want to be lifting a few times a week, eating a high-protein diet, eating enough to keep your muscle, and moving every day, so you keep what you worked for.
Why muscle loss is the real risk
To keep muscle, your body needs protein and enough fuel. When your appetite is suppressed, both get hard. In one large semaglutide trial, about 40% of the weight people lost was lean mass, which includes muscle (STEP 1 body-composition substudy). Some studies also suggest rapid weight loss can affect bone density.
Lose too much muscle and you lose strength, you burn fewer calories at rest, and everyday things get harder. For some people, that trade isn't worth it.
My honest take: if your doctor says you're at high risk of heart disease or another serious condition, these medications can make a lot of sense. For most people, go in with a plan to protect your muscle.
1. Hit your protein, even when you're not hungry
- Aim for at least your goal body weight in grams of protein a day, or 0.7 to 1 gram per pound.
- Eat protein first at every meal, before anything else fills you up.
- Use protein shakes, Greek yogurt and protein bars. Liquid and soft protein is easier to get down when your appetite is low.
- Spread it through the day, starting at breakfast.
2. Lift weights 2 to 3 times a week
Strength training tells your body to keep its muscle while you lose fat. Train full body, track your lifts, and keep getting stronger over time. Hitting personal records while you lose weight is a great sign you're losing fat, not muscle. Start with the beginner workout plan for women or men.
3. Eat enough to keep your muscle
Don't let the medication drive your calories so low that you can't recover or train hard. Losing weight slower and keeping your muscle beats losing it fast and losing your strength with it.
4. Move every day
Walk daily. Aim for more than 5,000 steps a day, ideally 6,000 or more. It's one of the habits that keeps the weight off later.
5. Plan for coming off
When people stop these medications, they often regain much of the weight. In the STEP 1 trial extension, people regained about two-thirds of the weight they'd lost within a year of stopping semaglutide (Wilding et al., 2022). The people who keep their results are the ones who built the habits while they were on it: lifting, high protein, enough food and daily movement.
Measure muscle, not just weight
The scale can't tell you whether you're losing fat or muscle. An InBody scan can. At Fig Performance in Placentia, we scan, build your training and protein plan, and re-scan to make sure the weight coming off is fat. Can't make it in person? Try online coaching.
This article is general fitness and nutrition guidance, not medical advice. Talk to your doctor before starting, stopping or changing any medication.
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