Strength training cut muscle loss on tirzepatide in one trial, but it did not stop it. In the T-REx trial in Nature Medicine, published online on November 9, 2026, adults on tirzepatide who also did three supervised one-hour strength sessions a week lost 3.57 kg of total lean mass over 40 weeks. The group on the drug alone lost 4.67 kg. The training group also got stronger, while strength fell in the drug-only group. Weight and fat loss were similar in both groups. Below is what the trial measured, where the news coverage differs from the paper, and what to ask before you change your plan.
Quick facts, as of 2026-11-11
| Item | Detail | Source |
|---|---|---|
| Published online | 2026-11-09 | Nature Medicine paper |
| Study design | Randomized controlled trial: tirzepatide alone vs tirzepatide plus resistance exercise, 40 weeks | Nature Medicine paper |
| Where | Single center, University of Western Australia, Perth | Nature Medicine paper |
| Who | 120 adults with overweight or obesity: 60 men and 60 postmenopausal women, mean age 57.7 (range 50.1 to 70.3), without diabetes or cardiovascular disease | Nature Medicine paper |
| Training | Three one-hour supervised group sessions a week in a gym, led by accredited exercise physiologists; adherence 91% | Nature Medicine paper |
| Total lean mass lost | 4.67 kg on tirzepatide alone; 3.57 kg with training (difference 1.09 kg, P<0.001) | Nature Medicine paper |
| Weight lost | 22.61 kg on tirzepatide alone; 22.28 kg with training (P=0.694) | Nature Medicine paper |
| Total fat mass lost | 17.19 kg on tirzepatide alone; 17.98 kg with training (P=0.700) | Nature Medicine paper |
| Strength | Rose with training, fell without it (table below) | Nature Medicine paper |
| Funding | Eli Lilly reviewed the protocol and supplied tirzepatide through an investigator-initiated program; it gave no other funding and had no role in conduct | Nature Medicine paper |
What did the strength training trial find?
Lean mass: how much was lost
Total lean soft tissue mass fell 4.67 kg on tirzepatide alone and 3.57 kg in the training group, a difference of 1.09 kg (95% CI 0.43 to 1.75). Lean mass in this trial is measured by DXA scan. It includes skeletal muscle along with other soft tissue, so it is not the same as muscle alone.
The authors estimate about 2.5 kg of skeletal muscle was lost on tirzepatide alone, compared with about 2 kg in the training group. For arms and legs (appendicular lean mass), the losses were 3.55 kg and 2.92 kg, a difference of 0.63 kg.
Strength: up with training, down without it
The trial tested one-rep max strength in three lifts. All between-group differences were P<0.001.
| Lift (one-rep max) | Tirzepatide alone | Tirzepatide plus training |
|---|---|---|
| Bench press | down 4.09 kg (8.4%) | up 4.68 kg (10.7%) |
| Lat pulldown | down 4.42 kg (6.5%) | up 8.58 kg (15.7%) |
| Knee extension | down 4.42 kg (9.0%) | up 5.88 kg (17.5%) |
The authors describe the net gain from training as about 20%. For context on what strength is, a 2018 review in Sports Medicine, strength training considerations on PubMed, says strength rests on muscle size and architecture along with neural factors such as motor unit recruitment.
Weight and fat loss
Weight loss and fat loss were similar in both groups. The trial did not find that training changed how much weight or fat you lose on tirzepatide.
Blood pressure, blood sugar and cholesterol
Blood pressure, glucose, insulin, HbA1c and lipids showed no differences between the groups over time. The authors say exercise did not materially change tirzepatide's benefits on these markers.
Side effects in the trial
Nausea affected about half of participants. Vomiting, constipation, diarrhea and indigestion each affected about one-third. Rates were similar in both arms. There were six serious adverse events (five on tirzepatide alone, one in the training group), all judged unrelated to tirzepatide or exercise. Of 120 enrolled, 111 (93%) completed the study. Withdrawals were adverse events (6), a breast cancer diagnosis (2) and personal reasons (1).
How was the trial run?
Everyone started tirzepatide. Doses were increased over time, and most people tolerated 15 mg weekly. The training group worked in five 8-week phases, moving from light and moderate technique work to moderate and vigorous strength and hypertrophy training. All participants were told to keep their protein intake steady, and no specific diet was provided. In a food-diary subset, energy and protein intake were similar in both arms.
What does this mean if you lift on tirzepatide?
Yahoo Health's republished Men's Fitness article, dated 2026-11-10, frames the issue this way. It says appetite-suppressing medications can create large calorie deficits, especially when people struggle to eat enough protein, and that resistance training plus adequate protein can improve the quality of weight loss. That article names no expert and no study. Read its points as its framing, and read the trial numbers above as what the trial measured.
The people this result describes are men and postmenopausal women aged 50 to 70 with overweight or obesity, who had no diabetes or heart disease and were sedentary when they started. The trial tested tirzepatide only.
If you already take tirzepatide, ask your prescriber how resistance training fits into your plan. Ask a pharmacist about any side effects you have had, such as nausea. If you want help building sessions, a qualified coach or exercise physiologist can set them up around your ability, which is how the trial's sessions were run.
Where does the news coverage differ from the paper?
Several outlets covered the study in November 2026. Their figures do not all match the paper, so check the numbers against the Nature Medicine paper before you quote them.
- Yahoo Health and Men's Fitness (2026-11-10) give no lean mass or strength figures.
- The RACGP newsGP coverage reports training reduced lean muscle and tissue loss by “up to 25%” and improved strength by 10%. The paper gives a 1.09 kg smaller total lean loss, about 23% of the drug-only loss, and strength gains of 10.7% to 17.5% with training.
- The paper's lean mass difference is in kilograms and sits within a 95% confidence interval of 0.43 to 1.75 kg.
What does the lead researcher say?
Winthrop Professor Danny Green led the study at the University of Western Australia's School of Human Sciences and HealthSpan Institute. In the University of Western Australia news release, he said: “We now know that muscle loss can be reduced and strength increased when regular resistance training is used alongside tirzepatide treatment.” The university, which ran the trial, calls it the first study to show the combined effects of a GLP-1 medicine and resistance training on body composition, muscle mass, strength and cardiovascular measures.
Speaking to newsGP, Green said muscle loss could not be fully prevented in the training group, but “the strength increased in the resistance training group” while strength fell quite a lot in the drug-only group. He said body composition was tracked every eight weeks with DEXA scans. He also called GLP-1 drugs “blockbuster drugs” that are “not the full toolkit,” and said GPs play a crucial role.
Common mix-ups to avoid
| What you may have read | What the trial measured |
|---|---|
| “Lean mass” means muscle | DXA lean soft tissue includes skeletal muscle along with other soft tissue. |
| Protein was the key | All participants were told to keep protein intake steady; no specific diet was provided. |
| Any strength training works | Three supervised one-hour group sessions a week, led by exercise physiologists, for 40 weeks. |
| The result applies to every GLP-1 drug | The trial tested tirzepatide only, in adults aged 50 to 70 without diabetes. |
| Training improved fat loss | Fat loss was similar in both groups (P=0.700). |
| Expert quotes in the Yahoo article | The article names no expert. Green's quotes come from the University of Western Australia release and newsGP. |
Before you change your plan
Take these questions to the people who can answer them:
- Your prescriber: whether resistance training fits your tirzepatide plan, and how your weight and muscle changes will be tracked.
- A pharmacist: how to manage nausea, vomiting or constipation if they affect you.
- A coach or exercise physiologist: how to structure sessions around your current ability, with the trial's supervised group format as a reference.
- Yourself: read the full T-REx paper in Nature Medicine before you repeat any number.
Key dates
- 2026-07-29: the paper was received by Nature Medicine.
- 2026-10-09: the paper was accepted.
- 2026-11-09: the paper was published online.
- 2026-11-10: Yahoo Health republished the Men's Fitness article.
- November 2026: University of Western Australia, Medical Xpress and newsGP coverage followed.
Related reading
If you are new to lifting, the weight training 101 guide covers the basics. For the fat-loss side of the picture, read strength training is key to long-term fat loss.
By the Gym Floor Guide Editorial Team
This article is for general information purposes only and does not constitute medical advice. Consult your doctor or qualified healthcare provider before making changes to your health routine.