Working Out on GLP-1: A Practical UK Guide (October 2026)

01 · The core answer

Is it okay to work out while taking GLP-1?

Yes, and it is built into how the medicine is meant to be used. Mounjaro (tirzepatide) is a prescription-only medicine used alongside a reduced-calorie diet and increased physical activity.¹ The headline trial figures say the same thing: in SURMOUNT-1, people taking tirzepatide alongside diet and exercise lost on average 15% of their body weight on 5mg, 19.5% on 10mg and 20.9% on 15mg over 72 weeks, compared with 3.1% with lifestyle changes alone.² These are trial averages, and individual results vary.

Treatment works alongside a reduced-calorie diet and increased physical activity, not instead of them.² So the question is rarely whether to move more, but how to do it in a way you can keep up while your appetite and energy are changing.

02 · Your next step

What should you actually do?

Begin with activity you already tolerate and make it regular before you make it hard. If you are new to exercise, walking is a sensible start, and you can add resistance-style sessions as confidence grows. If you have a heart condition, joint problems or other health concerns, speak to your prescriber or GP before changing your routine.

If you are not yet on treatment, our weight loss clinic explains how a free online consultation works, reviewed by a GPhC-registered prescriber. If you are ready to look at the medicine itself, see the Mounjaro pen prices and consultation page, where current pricing is shown live.

03 · Quick reference

Exercise and GLP-1: situations and sensible responses

04 · Why movement matters

Why movement matters on treatment

Mounjaro helps you eat less; exercise is the other half of the plan. Tirzepatide activates the GIP and GLP-1 receptors, which help regulate appetite, slow how quickly the stomach empties, and improve the way the body responds to insulin.¹ In practice, most people feel fuller sooner and less hungry between meals, which supports a reduced-calorie diet.

Notice what that describes: an effect on appetite and eating. It does not replace physical activity, and the licence wording pairs the medicine with increased physical activity for that reason.

The trial evidence also looks beyond the scales. Weight loss on tirzepatide came with average improvements in waist size, blood pressure, cholesterol and blood-sugar measures, and most participants with prediabetes returned to normal blood-sugar levels.² These are trial-average secondary outcomes, not promises, but they are why prescribers talk about weight management as health management rather than appearance. Regular activity is part of that wider health picture, whatever the number on the scales does.

05 · Starting out safely

How to start working out on GLP-1

Start smaller than you think you need to, and let the routine build before the intensity does. The first weeks on 2.5mg are about adjustment, and experiences differ widely: some people notice appetite change and early loss in week one, others feel little until a higher dose, and both are normal.¹³

That variation matters for training. Someone with very little appetite and low energy has different needs from someone who feels almost unchanged. Use your own energy as the guide rather than a plan written for someone else.

A sensible beginner approach looks like this:

• Choose activity you enjoy enough to repeat, such as walking, cycling, swimming or an easy class.
• Keep sessions comfortable at first, so you finish feeling better rather than flattened.
• Add variety gradually, including simple resistance work with light weights, bands or your own bodyweight.
• Increase one thing at a time: how long, how often or how hard, never all together.
• Keep a note of how you feel after injection day so you can spot your own pattern.

Our free companion app, GLPTrackr, can help you track your journey on iOS or Android, including how you feel from week to week.

If you are brand new to exercise, a local gym induction, a qualified instructor or your GP can help you learn technique safely. Tell them you are taking a GLP-1 medicine.

06 · Injection-day energy

Energy, nausea and injection-day timing

Expect your energy to vary across the week. Mild nausea, altered appetite and tiredness in the first days after each injection are the commonest early effects, and they usually settle.¹³ Many people therefore find that the days straight after an injection suit easier movement, while the later days of the week suit longer or harder sessions.

What you can do is watch your own pattern for a few weeks. If you consistently feel poor on the same days, put gentle walks there and move demanding sessions elsewhere.

Each time you step up to a higher strength, you may notice the pattern shift again. The dose ladder runs 2.5mg, 5mg, 7.5mg, 10mg, 12.5mg and 15mg, and a step up is a good moment to go back to gentler sessions for a short while before pushing again.

If nausea or tiredness is stopping you moving at all, or it is not settling, tell your prescriber at your monthly review or sooner. They can talk through your options within the licence.

07 · Fuelling and protein

Eating enough to train well

Training on very little food is a poor combination, and appetite suppression can make it easy to under-eat. Among the responses to a plateau are to review food intake honestly and protect protein and activity.⁴ That is why protein-containing meals and snacks are worth planning even when you are not hungry.

On the question of working out on an empty stomach, individual tolerance varies. If you feel light-headed, shaky or sick when you train fasted, that is a sign to eat something first and to mention it to your prescriber. A small, easy-to-digest snack is a reasonable thing to try if appetite is low.

Hydration also deserves attention when you are eating and drinking less than usual and sweating more. If nausea or vomiting is persistent or you cannot keep fluids down, contact your clinical team — dehydration needs prompt attention. Do not train through it.

08 · Muscle and body shape

Can you build muscle on GLP-1?

The practical position is cautious and sensible. If you are eating less, protecting protein and staying active is a sensible approach.⁴ Resistance-style training is a common-sense way to stay active, and many people use it to keep strength as the weight comes down.

Targeting one area, such as building glutes or losing belly fat, is a matter of overall training and overall body-weight change. Pick a routine you can repeat, include lower-body strength work if glutes are your aim, and judge progress over months.

Very short sessions are fine as a way to start. Something brief and regular beats an ambitious plan you abandon. Build duration as you feel able.

09 · Walking and cardio

Is walking enough on GLP-1?

Walking is a good, low-risk foundation, particularly in the early weeks. The licence says increased physical activity, and walking counts. It is easy on the joints, needs no equipment, and you can adjust it to how you feel on any given day.

As you get fitter, you can lengthen walks, add hills, or try cycling or swimming. Add resistance-style sessions when you feel ready if you want more than walking can offer. No type of activity is singled out, so choose the plan you will keep doing.

If walking is your main activity and your weight stalls, do not assume it is a failure of effort. Plateaus of a few weeks are normal and expected as the body adapts to a lower weight.⁴ Our guides on getting out of a GLP-1 stall and moving past a plateau go through the next steps in detail.

10 · If results slow down

What if you do not work out on GLP-1?

You can still lose weight, but you would be using the medicine without the part of the plan it was designed around. The licence pairs Mounjaro with a reduced-calorie diet and increased physical activity, and the trial averages were achieved alongside diet and exercise.²

If you are struggling to be active because of health, pain, mobility or confidence, that is a conversation for your prescriber, not a reason to feel guilty. Small steps count.

Weight loss on Mounjaro is gradual by design. Most measurable progress builds from 5mg onward, month by month, and trials measured results at 72 weeks. Think in months, not days, and judge progress by trend rather than individual weigh-ins.⁴ Your prescriber reviews your response: if you have lost less than 5% of your starting weight after 6 months on the highest dose you can tolerate, they will discuss whether continuing or stopping is right for you.

For ways to judge whether treatment is working, see how to know if GLP-1 is working, and for broader habits, how to get the most out of GLP-1.

11 · Appetite and exercise

Exercise, appetite and the bigger picture

Exercise can change how hungry you feel, and on GLP-1 treatment your appetite is already being altered by the medicine. We explore that interaction in our guide on whether working out suppresses appetite. If you find you are barely eating on training days, that is worth raising with your prescriber.

It also helps to remember what the medicine is. Tirzepatide has a half-life of about five days, so after a final dose it takes roughly four to five weeks to clear the system.¹ That is one reason to build habits that last beyond treatment: the routine you establish now is the part you keep.

Some people on GLP-1 medicines mention other products in the same breath as exercise. For anything unlicensed or unfamiliar, ask your prescriber first. A plateau is not a reason to double doses or add unlicensed products.⁴