GLP-1 medications can lead to meaningful weight loss. But the number on the scale doesn't show what you lost. Some of it is fat, and some is lean mass, which includes muscle. Keeping as much muscle as you can helps with strength, balance, everyday energy and how you feel as you age.
How much lean mass is lost on a GLP-1?
In the STEP-1 trial of semaglutide, published in the New England Journal of Medicine in 2021, adults lost about 15% of their body weight over 68 weeks on average. Body scans (DXA) in a subgroup showed that about 38–39% of the weight lost was lean mass.
That doesn't mean 4 in 10 pounds lost were pure muscle. DXA "lean mass" also counts water, glycogen and organ tissue, and people on placebo lost some lean mass too. But it is a clear reason to look after your muscle while your weight changes.
What experts recommend
In 2025, four US organizations (the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society) published joint nutrition priorities for GLP-1 therapy. They highlight adequate protein, strength training to preserve lean mass, and preventing micronutrient gaps.
5 habits to help protect muscle
1. Make protein part of every meal
When meals get smaller, protein is easy to crowd out. Start each meal with the protein portion: eggs, Greek yogurt, fish, chicken, tofu, beans or a protein shake. Your doctor or a registered dietitian can give you a personal daily target.
2. Strength train at least twice a week
US physical activity guidelines recommend muscle-strengthening activity on at least 2 days a week, working all major muscle groups. That can be weights, resistance bands or bodyweight moves like squats, wall push-ups and step-ups.
3. Keep moving most days
The same guidelines recommend about 150 minutes of moderate activity a week, such as brisk walking. Walking after meals is an easy place to start.
4. Stay hydrated
Muscle is mostly water, and the Wegovy and Zepbound labels warn that stomach side effects can lead to dehydration. See Electrolytes on a GLP-1: what you need to know.
5. Consider creatine, with your doctor's OK
Creatine is one of the most studied supplements and works best alongside resistance training. Research in women is growing. Read Creatine for women on a GLP-1: what the research says.
A simple weekly plan
| Day | Movement | Nutrition focus |
|---|---|---|
| Mon | Strength (full body, 20–30 min) | Protein at breakfast |
| Tue | 30-min walk | Fluids through the day |
| Wed | 30-min walk | Protein at every meal |
| Thu | Strength (full body, 20–30 min) | Water-rich foods |
| Fri | 30-min walk | Protein-first meals |
| Sat | Active fun: hike, swim, dance | Fluids through the day |
| Sun | Rest or gentle stretching | Plan next week's meals |
Check with your doctor before starting a new exercise plan, especially if you have heart, joint or other health conditions.
Where Zibby fits
Zibby Hydration combines electrolytes, vitamins C, B6 and B12 and 1,360 mg of creatine monohydrate in one zero-sugar stick, made for women on a GLP-1 routine. It is a small, easy addition to the habits above, not a replacement for protein, movement or medical advice. See what's inside →
Frequently asked questions
Do GLP-1 medications cause muscle loss?
Weight loss of any kind includes some lean mass. In the STEP-1 semaglutide trial, about 38–39% of weight lost was lean mass on DXA scans, which also counts water and organ tissue.
How can I keep muscle on Ozempic or Wegovy?
Experts recommend adequate protein, strength training at least twice a week, regular activity and staying hydrated. Ask your care team for personal targets.
How much strength training do I need?
US guidelines recommend muscle-strengthening activity at least 2 days a week, working all major muscle groups.
Sources
- GLP-1s and muscle loss: what the evidence shows (summarizing Wilding et al., NEJM 2021, STEP-1)
- Nutritional Priorities to Support GLP-1 Therapy for Obesity (ACLM, ASN, OMA, TOS, 2025)
- CDC: Physical activity guidelines for adults
- Wegovy prescribing information
This article is for general education and is not medical advice. *These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.