# How to keep your muscle on GLP-1s and other weight-loss drugs

> In the big trials, lean mass made up about 25% of the weight lost on tirzepatide and about 38 to 45% on semaglutide. Lifting weights at least 3 times a week, 150+ minutes of cardio and about 1.2 to 1.6 g of protein per kg a day are the best-supported ways to keep muscle while the scale drops, and exercise also helps keep the weight off.

Source: https://templatetrainer.com/guides/glp-1-muscle-loss/ · By Jordan DuBois · Updated 2026-10-25 · Template Trainer

*This guide is general information, not medical advice. Talk to your doctor or prescriber before starting, stopping or changing a medication, supplement or exercise program, especially if you have a health condition.*

GLP-1 medications like semaglutide and tirzepatide led to large weight losses in their clinical trials. But the scale doesn't tell you *what* you lost. In the major trials, a real share of the weight that came off was lean mass, and some of that is muscle you'd rather keep.

The good news is that the tools to protect it are the same ones this site is about: lifting weights with steady [progressive overload](https://templatetrainer.com/guides/progressive-overload/), doing some cardio, and eating enough protein. This guide covers what the research shows about muscle loss on GLP-1s and other weight-loss drugs, which supplements are worth your money, and how to set up your training while you're on them.

## What are GLP-1 drugs?

GLP-1 receptor agonists copy a gut hormone (glucagon-like peptide-1) that tells your brain you're full. Tirzepatide also copies a second hormone, GIP. The result is much less appetite, so you eat less without having to fight hunger all day.

They aren't the only prescription option. These are the weight-management medications the U.S. National Institutes of Health lists as FDA-approved:

| Medication (brand) | How it works | How it's taken |
| --- | --- | --- |
| Semaglutide (Wegovy) | Mimics GLP-1 to reduce appetite | Weekly injection |
| Tirzepatide (Zepbound) | Mimics GIP and GLP-1 to reduce appetite | Weekly injection |
| Liraglutide (Saxenda) | Mimics GLP-1 to reduce appetite | Daily injection |
| Phentermine-topiramate (Qsymia) | Phentermine lessens appetite, combined with topiramate | Daily pill |
| Naltrexone-bupropion (Contrave) | A combination that may reduce hunger | Daily pills, with the dose built up over the first weeks |
| Orlistat (Xenical, and lower-dose Alli without a prescription) | Reduces how much fat your gut absorbs | Pill 3 times a day |
| Setmelanotide (Imcivree) | Acts on brain appetite pathways | Daily injection, only for rare genetic causes of obesity |

Phentermine on its own is also approved, but only for a few weeks of use. NIDDK notes that people taking a medication alongside a lifestyle program lose about 3 to 12% more of their starting weight after a year than with lifestyle changes alone, and that these drugs "work best when combined with a lifestyle program."

The rest of this guide focuses on GLP-1s, because that's where the body composition research is. But the training and protein advice applies to any big weight loss, with or without a drug. For the whole plan, from calories and meals to cardio and sleep, see [the ultimate fat loss guide](https://templatetrainer.com/guides/fat-loss-guide/).

## How much weight do people lose on GLP-1s?

In the main trials:

- **Semaglutide:** in the STEP 1 trial of 1,961 adults, people on semaglutide 2.4 mg lost an average of 14.9% of their body weight over 68 weeks, compared with 2.4% on placebo.
- **Tirzepatide:** in the body composition substudy of the SURMOUNT-1 trial, people on tirzepatide lost an average of 21.3% of their body weight over 72 weeks, compared with 5.3% on placebo.

For someone starting at 100 kg (220 lb), that's 15 to 21 kg (33 to 47 lb). The question is how much of it was fat.

## How much of the weight lost is muscle?

Both trials scanned a group of participants with DXA, which splits the body into fat mass and lean mass:

| Trial | Weight lost | Fat mass | Lean mass | Share of the loss that was lean mass |
| --- | --- | --- | --- | --- |
| STEP 1 (semaglutide) | 14.9% | Down 8.3 kg | Down 5.3 kg | About 38% (a 2024 review calculated 45% using different figures) |
| SURMOUNT-1 (tirzepatide) | 21.3% | Down 33.9% | Down 10.9% | About 25% |

That looks alarming, but three details matter:

1. **Lean mass isn't all muscle.** DXA lean mass also counts organs, bone, fluids and the water in fat tissue. The 2025 joint nutrition advisory from four obesity and nutrition societies estimates that, because muscle is about half of lean mass, roughly 20% of the weight lost on semaglutide in STEP 1 was muscle.
2. **It isn't unique to the drugs.** In SURMOUNT-1, about 75% of the weight lost was fat and 25% lean for both tirzepatide *and* placebo. A 2024 review found the share of lean mass lost is similar whether weight comes off through diet, GLP-1 drugs or surgery. You lose more muscle on a GLP-1 mostly because you lose more weight, faster, while eating much less.
3. **Muscle quality can improve.** The same review reports that MRI studies of liraglutide and tirzepatide found less fat stored inside the muscle after treatment.

So the drug isn't eating your muscle. But a big, fast weight loss with a small appetite is exactly the setting where muscle goes if you give your body no reason to keep it. The review flags older adults, people who get little or no exercise and people with poor nutrition as most at risk of sarcopenia (age-related muscle loss).

## Why lifting weights matters on a GLP-1

Eating less gives your body a reason to shed tissue. Lifting gives it a reason to keep muscle.

The clearest evidence comes from a 2017 trial in the New England Journal of Medicine. Researchers split 160 older adults with obesity into a control group or a weight-loss diet plus aerobic training, resistance training, or both. All three diet-and-exercise groups lost about 9% of their body weight in 6 months, but what they lost was different:

| Group | Lean mass lost | Physical performance score | Hip bone density |
| --- | --- | --- | --- |
| Aerobic only | 2.7 kg (5%) | Up 14% | Down about 2.6% |
| Resistance only | 1.0 kg (2%) | Up 14% | No significant change |
| Aerobic plus resistance | 1.7 kg (3%) | Up 21% | Down about 1.1% |

Lifting cut the lean mass lost by more than half compared with cardio alone and protected bone. Doing both gave the biggest boost in day-to-day physical function.

The trial wasn't on GLP-1s, but a Danish trial was. In a 2021 NEJM study, 195 adults who had lost about 12% of their weight on a low-calorie diet were assigned to a year of supervised exercise, the GLP-1 drug liraglutide, both, or placebo. Exercise was associated with an increase in lean mass, the combination preserved lean mass, and the combination cut body fat percentage by 3.9 percentage points more than placebo, about twice as much as either treatment alone. The authors concluded that combining exercise with liraglutide "improved healthy weight loss maintenance more than either treatment" on its own.

The 2025 joint advisory recommends strength training **at least 3 times a week** plus **at least 150 minutes of moderate-intensity aerobic exercise a week** for people on GLP-1 therapy.

## Why cardio still matters

Lifting protects muscle; cardio does other jobs. The Physical Activity Guidelines for Americans recommend 150 to 300 minutes a week of moderate-intensity activity (or 75 to 150 minutes of vigorous activity) plus muscle-strengthening work on 2 or more days, for everyone, not just people losing weight.

On a GLP-1, cardio earns its place for two reasons from the trials above:

- **Exercise helps keep the weight off.** In the liraglutide trial, the placebo group regained an average of 6.1 kg in the year after their diet, the exercise group regained only about 2 kg, and the exercise-plus-liraglutide group kept losing (3.4 kg more).
- **Together with lifting, it does the most for how well you move.** The combined group in the 2017 trial had the biggest jump in physical performance.

The catch is that cardio alone, as the table shows, protected the least lean mass and bone. Do it as well as lifting, not instead of it.

## What happens when you stop the medication?

This is where training matters most. In the STEP 1 extension, people who stopped semaglutide after 68 weeks regained about two-thirds of the weight they had lost within a year. In the SURMOUNT-4 trial, people who switched from tirzepatide to placebo after 36 weeks regained 14% of their body weight over the next year, while those who stayed on it lost another 5.5%.

If you lost muscle along with fat and then regain the weight, there's a risk of ending up at a similar weight with less muscle than you started with. NIDDK notes that "you probably will regain some weight" after stopping, and that healthy eating and regular physical activity may help limit it. Building the lifting habit *while* you're on the medication means it's already in place if you ever come off.

## How to train while on a GLP-1

There's no special GLP-1 workout. The goal is simple: keep giving your muscles a reason to stay, while eating less than you ever have. In practice:

- **Lift at least 3 days a week**, working every major muscle group. Full-body sessions make this easy: squat or leg press, a hinge (deadlift or Romanian deadlift), a press, a row or pull-down, and a few accessories.
- **Keep the weights challenging.** The signal to keep muscle comes from hard sets, so finish most working sets with only a few good reps left in the tank. Our guide to [RPE and reps in reserve](https://templatetrainer.com/guides/what-is-rpe/) explains how to judge that.
- **Aim to hold or slowly add weight.** In a calorie deficit, holding your strength is a win. If your lifts are holding while the scale drops, you're very likely keeping muscle.
- **Cut volume before you cut weight** on low-energy days, especially in the first weeks of a new dose. Two hard sets beat skipping the session.
- **Add cardio on top**, building to 150 minutes or more a week. Brisk walking counts.

Here's one way to fit the advisory's 3 strength days and 150 minutes of cardio into a week:

| Day | Strength (45 to 60 min) | Cardio |
| --- | --- | --- |
| Monday | Full body A: squat, bench press, row, accessories | 15-minute walk after |
| Tuesday | Rest from lifting | 30-minute brisk walk or bike |
| Wednesday | Full body B: deadlift, overhead press, pull-down, accessories | 15-minute walk after |
| Thursday | Rest from lifting | 30-minute brisk walk or bike |
| Friday | Full body A again | 15-minute walk after |
| Saturday | Rest from lifting | 45-minute hike, swim or long walk |
| Sunday | Full rest | None |

That's 3 strength sessions and 150 minutes of cardio. If you're new to lifting, a beginner program like StrongLifts 5x5 or GZCLP gives you the structure; see [how to choose a workout program](https://templatetrainer.com/guides/how-to-choose-a-workout-program/) for which fits you.

## How much protein do you need on a GLP-1?

When you're eating much less, protein is the part of your diet to protect first. The joint advisory notes the standard adult allowance is 0.8 g per kg of body weight a day, and that higher targets of **1.2 to 1.6 g/kg a day**, or an absolute target of **80 to 120 g a day**, have been proposed during active weight loss. The 2024 review is honest that it is "not clear how much protein should be recommended" specifically for people on these drugs.

For lifters, a 2018 meta-analysis of 49 studies and 1,863 people found that extra protein improved muscle gains from resistance training, with no further benefit beyond about **1.62 g/kg a day** of total protein.

| Your weight | 1.2 g/kg a day | 1.6 g/kg a day |
| --- | --- | --- |
| 60 kg (132 lb) | 72 g | 96 g |
| 80 kg (176 lb) | 96 g | 128 g |
| 100 kg (220 lb) | 120 g | 160 g |
| 120 kg (265 lb) | 144 g | 192 g |

With a small appetite, the higher numbers can be hard to eat. Practical tips: eat the protein on your plate first, spread it over 3 to 4 meals, and lean on easy options like Greek yogurt, eggs, lean meat, fish, tofu and protein shakes. The advisory also stresses drinking enough fluids, since vomiting or diarrhea can cause dehydration.

## Which supplements help, and which don't?

### Worth considering

- **Protein powder.** Not magic, just an easy way to reach your protein target when you're not hungry. The meta-analysis above studied protein supplements.
- **Creatine.** A 2017 meta-analysis of 22 trials in 721 adults aged about 57 to 70 found that creatine taken during resistance training added 1.37 kg more lean mass than placebo, plus small gains in upper- and lower-body strength. The International Society of Sports Nutrition's position stand reports creatine has been used safely in healthy people at doses up to 30 g a day for 5 years. It works with training, not instead of it.
- **Vitamins and minerals, if your diet falls short.** Eating much less makes it harder to get enough nutrients. The joint advisory lists iron, calcium, magnesium, zinc and vitamins A, D, E, K, B1, B12 and C as nutrients of concern, and says supplements such as vitamin D, calcium, B12 or a multivitamin may be considered for those at risk.

### Weight-loss supplements

Most "fat burner" ingredients have weak or no evidence. The NIH Office of Dietary Supplements' review of weight-loss supplements found, for example:

| Ingredient | What the evidence shows |
| --- | --- |
| Green tea | Any effect is small and not likely to be clinically relevant. Green tea *extract* has been linked to liver damage in case reports. |
| Garcinia cambogia | Conflicting evidence, and its long-term safety is unknown. |
| Glucomannan | Inconsistent effects. Tablets have been linked to blockages of the esophagus. |
| Chitosan | High-quality trials show minimal effects on body weight. |
| Conjugated linoleic acid (CLA) | Small effects of questionable clinical relevance. |
| Probiotics | Inconsistent results. |
| Raspberry ketone | Not enough research to draw conclusions. |
| Bitter orange (synephrine) | Weak, contradictory evidence and significant safety concerns. |

None of them comes close to a prescription drug, and none replaces training and protein.

### Compounded and "research" GLP-1s

The FDA warns that compounded drugs, including compounded semaglutide and tirzepatide, are not FDA-approved, so they aren't reviewed for safety, effectiveness or quality before they're sold. As of May 2026 it had received about 990 adverse event reports for compounded semaglutide and more than 730 for compounded tirzepatide, some needing hospital care and some tied to dosing errors, and it has found counterfeit Ozempic in the U.S. supply chain. Its advice: get a prescription from a licensed provider, fill it at a state-licensed pharmacy, and don't use an injectable GLP-1 that arrives warm.

## How to tell if you're keeping your muscle

You don't need a DXA scan to get a good signal. Track two things:

1. **Your bodyweight**, once or twice a week at the same time of day.
2. **Your strength** on a few main lifts.

If the scale is dropping and your lifts are holding or climbing, your strength relative to your bodyweight is rising, which is what you want. If your lifts are sliding week after week, look at your protein, your sleep and your training volume, and talk to your prescriber about the pace of your weight loss.

In Template Trainer you can log your weight in the **Bodyweight** card in Profile, which charts it and shows your 30-day change, and the **Relative strength** card on Progress shows each main lift's estimated 1 rep max as a multiple of your latest bodyweight. Your program's progression rules set each session's weights, so you can see straight away if a lift stops moving.

## When to talk to your doctor

Your prescriber should know you're training, especially if you're starting a new program. Side effects are common: in STEP 1, 44% of people on semaglutide reported nausea, 32% diarrhea, 25% vomiting and 23% constipation, compared with 17%, 16%, 7% and 10% on placebo. Feeling dizzy, faint or unable to keep fluids down during training is a reason to stop and get checked. If you're older, have a medical condition or are losing weight very quickly, ask about a body composition scan and a referral to a dietitian.

## Frequently asked questions

### Do GLP-1 drugs like Ozempic and Wegovy cause muscle loss?

They cause weight loss, and part of any large weight loss is lean mass. In the trials, lean mass was about 25% of the weight lost on tirzepatide and about 38 to 45% on semaglutide, but lean mass includes water, organs and bone, and only about half of it is muscle. The share is similar to weight loss from dieting. Lifting weights and eating enough protein reduce how much muscle you lose.

### Can you build muscle while on semaglutide or tirzepatide?

In the drug trials, lean mass fell on average as weight came off, so for most people the realistic goal is to keep as much muscle as possible and hold or build strength. Training can do more than slow the loss, though: in the 2021 liraglutide trial, exercise was associated with an increase in lean mass in the year after a diet.

### How much protein should I eat on a GLP-1?

A 2025 joint advisory notes targets of 1.2 to 1.6 g per kg of body weight a day, or 80 to 120 g a day, have been proposed during active weight loss. Research on lifters finds little added benefit above about 1.6 g/kg a day. Ask a dietitian to set a target for you, especially if you have kidney disease.

### Is cardio or weights better while taking a GLP-1?

Do both. In a trial of dieting older adults, lifting protected about twice as much lean mass as cardio alone, and doing both improved physical function the most. Aim for strength training at least 3 times a week and 150 minutes or more of moderate cardio.

### Will I regain the weight if I stop?

Most people regain much of it. A year after stopping, people in the STEP 1 extension had regained about two-thirds of the weight they lost on semaglutide, and in SURMOUNT-4 people switched to placebo regained 14% of their body weight. In a liraglutide trial, people who exercised kept off more weight, so building the habit now helps.

### Should I take creatine on a GLP-1?

Creatine is one of the best-studied supplements. Taken with resistance training, it added about 1.4 kg of lean mass over placebo in a meta-analysis of older adults, and it has a strong safety record in healthy people. Check with your doctor first if you have kidney disease or take other medications.

## Sources

- [Wilding et al. (2021), Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1), New England Journal of Medicine](https://doi.org/10.1056/NEJMoa2032183)
- [Look et al. (2025), Body composition changes during weight reduction with tirzepatide in the SURMOUNT-1 study of adults with obesity or overweight, Diabetes, Obesity and Metabolism](https://doi.org/10.1111/dom.16275)
- [Neeland, Linge and Birkenfeld (2024), Changes in lean body mass with glucagon-like peptide-1-based therapies and mitigation strategies, Diabetes, Obesity and Metabolism](https://doi.org/10.1111/dom.15728)
- [Mozaffarian et al. (2025), Nutritional priorities to support GLP-1 therapy for obesity: a joint Advisory from the ACLM, ASN, OMA and The Obesity Society, American Journal of Clinical Nutrition](https://doi.org/10.1016/j.ajcnut.2025.04.023)
- [Villareal et al. (2017), Aerobic or Resistance Exercise, or Both, in Dieting Obese Older Adults, New England Journal of Medicine](https://doi.org/10.1056/NEJMoa1616338)
- [Lundgren et al. (2021), Healthy Weight Loss Maintenance with Exercise, Liraglutide, or Both Combined, New England Journal of Medicine](https://doi.org/10.1056/NEJMoa2028198)
- [Wilding et al. (2022), Weight regain and cardiometabolic effects after withdrawal of semaglutide: The STEP 1 trial extension, Diabetes, Obesity and Metabolism](https://doi.org/10.1111/dom.14725)
- [Aronne et al. (2024), Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity: The SURMOUNT-4 Randomized Clinical Trial, JAMA](https://doi.org/10.1001/jama.2023.24945)
- [Morton et al. (2018), A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults, British Journal of Sports Medicine](https://doi.org/10.1136/bjsports-2017-097608)
- [Chilibeck et al. (2017), Effect of creatine supplementation during resistance training on lean tissue mass and muscular strength in older adults: a meta-analysis, Open Access Journal of Sports Medicine](https://doi.org/10.2147/OAJSM.S123529)
- [Kreider et al. (2017), International Society of Sports Nutrition position stand: safety and efficacy of creatine supplementation in exercise, sport, and medicine, Journal of the International Society of Sports Nutrition](https://doi.org/10.1186/s12970-017-0173-z)
- [Piercy et al. (2018), The Physical Activity Guidelines for Americans, JAMA](https://doi.org/10.1001/jama.2018.14854)
- [NIDDK (2024), Prescription Medications to Treat Overweight and Obesity, National Institutes of Health](https://www.niddk.nih.gov/health-information/weight-management/prescription-medications-treat-overweight-obesity)
- [NIH Office of Dietary Supplements (2026), Dietary Supplements for Weight Loss: Fact Sheet for Health Professionals](https://ods.od.nih.gov/factsheets/WeightLoss-HealthProfessional/)
- [U.S. Food and Drug Administration (2026), FDA's Concerns with Unapproved GLP-1 Drugs Used for Weight Loss](https://www.fda.gov/drugs/drug-alerts-and-statements/fdas-concerns-unapproved-glp-1-drugs-used-weight-loss)

## About the author

Jordan DuBois has been lifting for 20 years and won the men's open lightweight class at the 2013 NPC Natural Western in Arizona as a natural, after placing 2nd at the 2011 NPC Western Regional. Jordan holds summa cum laude degrees in applied mathematics and biology from Arizona State University, and founded Template Trainer to run proven programs the way their authors wrote them. [Bio](https://templatetrainer.com/authors/jordan-dubois/)