If you are using a weight-loss injection such as semaglutide or tirzepatide, exercise matters more, not less. These medicines reduce appetite so effectively that some of the weight you lose can be muscle. Strength training two or three times a week, enough protein at every meal, and good hydration are the best ways to make sure you lose mostly fat and keep the strength and shape you want.
I’m Gawhar Ahmad, a licensed pharmacist and the head coach at Being Fit. We do not prescribe medicines. But I understand how they work, and I can help you train and eat in a way that supports your treatment and your doctor’s plan.
Key takeaways
- Semaglutide and tirzepatide are prescription medicines that reduce appetite. They are meant to be combined with diet and exercise.
- Some weight lost on these medicines is lean mass. Estimates in trials vary widely, from about 15% or less to 40–60% of total weight lost.
- Strength training and enough protein are the main tools to protect muscle, according to a 2025 joint advisory.
- Nausea and reduced appetite make hydration and small, protein-rich meals especially important in Dubai’s heat.
- In the STEP 1 extension, people regained about two-thirds of the weight lost within a year of stopping. Habits are what last.
How do weight-loss injections work?
According to the NHS, semaglutide (brands include Wegovy and Ozempic) is a GLP-1 agonist that reduces your appetite and helps you feel fuller for longer. It is only available on prescription and is used to treat obesity, or manage type 2 diabetes, alongside exercise and changes to your diet. Tirzepatide (Mounjaro) works in a similar way but activates two gut hormone receptors, GLP-1 and GIP.
The results can be substantial. In the STEP 1 trial, adults with obesity or overweight who used semaglutide for 68 weeks, alongside a lifestyle programme, lost an average of 14.9% of their body weight, compared with 2.4% on placebo.
Will I lose muscle on semaglutide or tirzepatide?
Some, yes. Whenever you lose weight, part of it is lean mass. With these medicines, the question is how much. A 2024 review found wide variation across trials: in some, lean mass made up 40% to 60% of total weight lost, while in others it was about 15% or less. The authors point out that lean mass includes organs, bone and water, not just muscle, and that imaging studies suggest the muscle changes may be largely in proportion to the weight lost. They also note that older age and more severe disease may increase the risk of losing too much muscle.
In plain terms, nobody can promise you will lose only fat. But you can tilt the odds in your favour, and that is where training and nutrition come in.
How should I exercise on a weight-loss injection?
A 2025 joint advisory from four US medical and nutrition organisations recommended preserving muscle and bone through resistance training and appropriate diet during GLP-1 treatment, along with checking muscle strength, function and body composition at the start. Here is how I translate that into practice:
- Strength train two or three times a week. Full-body sessions with squats, hinges, pushes and pulls. Progress gradually.
- Keep walking. Aim for regular daily steps and at least 150 minutes a week of moderate activity.
- Adjust on difficult days. If nausea or tiredness is worse, for example after a dose increase, swap a hard session for a walk or mobility work.
- Track strength, not just weight. If your weight is dropping fast but your strength is falling too, your plan needs adjusting.
- Measure body composition. It shows whether you are losing fat or muscle.
Our guide to building lean muscle after 30 explains how to structure strength sessions, and strength training for women tackles common worries about lifting weights.
What should I eat to protect muscle?
When your appetite is low, it is easy to eat too little protein. Prioritise it:
- Protein first at every meal. Eggs, Greek yoghurt, fish, chicken, lentils, tofu or cottage cheese. Aim for a palm-sized portion or more.
- Smaller, more frequent meals are often easier if you feel full quickly or nauseous.
- Vegetables, fruit and whole grains for fibre, vitamins and minerals, which can run low when you eat much less.
- Limit greasy, very sweet and very large meals, which tend to worsen nausea for many people.
The 2025 advisory also highlighted the risk of nutrient deficiencies when calorie intake drops a lot. If you are eating very little, ask your doctor whether a blood test or supplement is needed. Our pharmacist’s guide to supplements explains which are worth considering.
What side effects affect training?
The NHS lists nausea, vomiting, constipation, diarrhoea and tiredness among the common side effects of semaglutide. These matter for training in three ways:
- Dehydration. Vomiting and diarrhoea lose fluid. In Dubai’s heat, that combination can make you dizzy during exercise. Drink regularly and train indoors when it is hot. See our heat and hydration guide.
- Low energy. Eating very little can leave you flat. A small snack containing protein and carbohydrate an hour or two before training often helps.
- Low blood sugar. The NHS warns that low blood sugar is more likely if semaglutide is used with other diabetes medicines such as insulin. Exercise can lower blood sugar further. If you use these, tell your coach and follow your doctor’s advice.
Stop exercising and seek medical help if you have severe stomach pain that does not go away, which can be a sign of an inflamed pancreas, or symptoms of an allergic reaction.
Is it safe to buy weight-loss injections online?
Be very careful. In 2024, the World Health Organization issued an alert about falsified semaglutide products and reported increasing reports of fakes in all regions since 2022. Fake products may contain the wrong dose, no active ingredient, or a different medicine such as insulin. The NHS advises buying only from a registered pharmacy. As a pharmacist, my advice is simple: only use a medicine prescribed for you by a licensed doctor and dispensed by a licensed pharmacy, and never share pens.
What happens when I stop the injections?
Weight often returns. In an extension of the same trial, people who stopped semaglutide regained about two-thirds of the weight they had lost within a year, and many health improvements faded. Talk to your doctor before stopping, and never stop suddenly without advice if you have type 2 diabetes.
This is why the habits you build while on treatment matter so much. Strength, an active routine and a way of eating you can sustain are what protect your results when the medicine ends.
How can Being Fit help?
We coach clients alongside their doctor’s treatment plan. Our assessment covers posture, movement, mobility and body composition, and every package includes a customised nutrition plan, progress tracking of weight, body fat and strength, and lifestyle coaching. If you are not sure whether you need a check-up first, read blood tests before training. Packages start at AED 3,600 a month; see our packages page.
Using a weight-loss medicine and want to protect your muscle? Book your free trial and assessment, WhatsApp us on 058 572 2691 or email info@beingfit.ae. Every way to reach us is on our contact page.
Frequently asked questions
Can I exercise while taking semaglutide or tirzepatide?
Yes, and you should. The NHS describes these medicines as working best combined with exercise and diet changes. Check with your doctor if you have other health conditions.
How do I avoid losing muscle on weight-loss injections?
Strength train two or three times a week, eat protein at every meal, stay active daily and track your strength and body composition, not just your weight.
Why do I feel dizzy when I train on semaglutide?
Possible reasons include dehydration, eating too little or low blood sugar if you also take other diabetes medicines. Stop, rest, drink water and speak to your doctor if it continues.
Will I regain weight when I stop?
Many people do. In the STEP 1 extension, people regained about two-thirds of lost weight within a year. Strong habits reduce that risk.
Does Being Fit prescribe weight-loss injections?
No. We do not prescribe medicines. We coach your training, nutrition and lifestyle alongside your doctor’s treatment.
Sources
- NHS: Semaglutide
- NHS: Tirzepatide
- Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity (STEP 1). N Engl J Med, 2021
- Wilding JPH, et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension. Diabetes Obes Metab, 2022
- Neeland IJ, et al. Changes in lean body mass with GLP-1-based therapies and mitigation strategies. Diabetes Obes Metab, 2024
- Mozaffarian D, et al. Nutritional priorities to support GLP-1 therapy for obesity: a joint advisory. Am J Clin Nutr, 2025
- World Health Organization: WHO issues warning on falsified medicines used for diabetes treatment and weight loss (2024)
This article is general information, not medical advice, and does not recommend any medicine. Weight-loss medicines must be prescribed and monitored by a doctor. Do not start, stop or change a medicine without medical advice. Prices are Being Fit’s published monthly packages as of October 2026 and may change.
