Taking Mounjaro or Wegovy? You might be finding it harder to hit your daily protein target. Both medicines suppress your appetite, so you end up eating smaller portions, and it's easy to fall behind on protein without realising.
Getting enough protein matters more on a GLP-1 medicine, because it's one of the few things within your control that helps protect your muscle while you lose weight. This guide covers how much protein you need on Wegovy or Mounjaro, how protein quality plays into that, and ways to hit your target even when your appetite is low.
A smaller appetite makes it easy to fall short without noticing. A rough daily tally of your protein can help.
Why protein intake matters more on a GLP-1 medication
Mounjaro (tirzepatide) and Wegovy (semaglutide) mimic gut hormones that reduce your appetite and slow how quickly your stomach empties. That's why meals feel filling much sooner than they did before treatment.
Smaller meals mean fewer calories overall. And protein tends to be more filling and slower to digest than other nutrients, which can reduce how much you eat even further.
This matters because any calorie deficit, whether from diet, medication or both, makes your body break down some muscle along with fat. A body scan (DXA) substudy of the SURMOUNT-1 trial found that around a quarter of the weight lost on tirzepatide came from lean mass, with the other three quarters from fat.1
We've covered the full picture in our article on whether Mounjaro or Wegovy causes muscle loss. Alongside resistance training, getting enough protein is the other main way to keep your muscle-to-fat balance working in your favour.
Protein and resistance training work as a team. One gives your muscles the raw materials, the other gives them a reason to stay.
Muscle isn't just about strength or appearance. It plays a part in your resting metabolic rate, which is the energy your body burns just keeping itself running. It also supports blood sugar control and everyday movements like climbing stairs or carrying shopping.
Losing too much muscle along with fat can leave you lighter on the scale but weaker. It may also make it easier to regain weight once treatment stops.
How much protein do you actually need?
The UK's official reference intake for protein is 0.75g per kilogram of body weight a day. That works out at around 56g a day for a 75kg adult.2
That figure is designed to prevent deficiency in generally healthy, inactive people. It isn't meant to protect muscle while you're actively losing weight.
If you're in a calorie deficit, whether from a GLP-1 medicine, dieting or both, the evidence points to a higher target. The International Society of Sports Nutrition's position stand on protein and exercise recommends 1.2g to 2.4g per kilogram of body weight a day for people cutting calories while trying to keep their muscle. Intakes towards the higher end offer more protection if you're also resistance training.3
In practice, most people on Mounjaro or Wegovy do well aiming for 1.2g to 1.6g per kilogram of body weight a day:
- If you weigh 60kg, that's roughly 72g to 96g of protein a day
- If you weigh 75kg, that's roughly 90g to 120g of protein a day
- If you weigh 90kg, that's roughly 108g to 144g of protein a day
Quick maths: multiply your weight in kg by 1.2 for the bottom of your range, and by 1.6 for the top.
These are starting points, not fixed rules. If you're also doing regular resistance training, you may benefit from the upper end of the range. And it's worth revisiting your target if your weight changes a lot during treatment.
Does protein quality matter, or just quantity?
Not all protein sources are equal when it comes to supporting muscle. Animal proteins such as eggs, dairy, fish and meat contain all nine essential amino acids in the proportions your body needs. That includes leucine, which plays a key role in triggering muscle building.
Plant proteins such as beans, lentils and tofu are still valuable. But many are lower in one or more essential amino acids, so eating a variety across the day, rather than relying on one source, helps close that gap.
That doesn't mean you need meat at every meal. Combining sources, like beans with rice or hummus with wholegrain bread, gives you a more complete mix of amino acids over the day, even if no single meal is perfectly balanced.
Practical ways to hit your protein target with a smaller appetite
Eating enough protein when you fill up quickly means changing how you eat, not just what you eat:
- Eat protein first - start each meal with the protein before the vegetables or carbs, so you get through it while your appetite is at its highest
- Choose protein-dense foods - eggs, Greek yoghurt, cottage cheese, fish and lean meat pack more protein into a smaller volume than many starchy or plant-based alternatives
- Spread protein across the day - three smaller protein-containing meals or snacks are usually easier to manage than one big portion at dinner
- Use a protein shake as a backup - a shake between meals is a practical way to close the gap on days when solid food feels difficult, though it shouldn't be your only source of protein
- Keep portions realistic - a palm-sized portion of meat or fish, a pot of yoghurt or two eggs are more achievable than a full traditional plate, and several smaller targets across the day soon add up
Should you use a protein supplement?
A protein shake or bar isn't essential. But it can be genuinely useful if your appetite makes it hard to eat enough whole food.
Whey protein is well absorbed and convenient. Most standard shakes give you 20g to 30g of protein in a small volume, which is often easier to manage than the same amount from solid food.
Vegetarian, vegan or avoiding dairy? Pea, soy and other plant-based protein powders are reasonable alternatives. Check the label, though, as some plant blends give you less protein per scoop than whey.
Supplements work best for closing a gap, not replacing proper meals.
If you're relying on shakes for most of your protein because solid food constantly feels like too much, mention it to your prescriber. It may be a sign that your dose or titration schedule needs a review.
Managing protein intake on higher-nausea days
Nausea is one of the most commonly reported side effects of both medicines, especially in the days after a dose increase. It often makes protein-rich foods feel unappealing before anything else.4 On days when nausea is worse:
- Choose cold or room-temperature protein, such as yoghurt, cottage cheese or a protein shake, which tends to go down better than hot, rich meals
- Eat smaller amounts more often rather than trying to finish a full meal in one go
- Avoid very high-fat protein sources for now, since these can be slower to digest and may make nausea worse
- Focus on getting some protein in rather than hitting your exact target, because a partial amount most days beats an empty plate
Can't keep any food or fluids down? Contact your prescriber or GP the same day, rather than waiting it out.
Can you take too much protein?
For most healthy adults, protein intakes up to around 2g per kilogram of body weight a day are considered safe. The evidence doesn't support the idea that ordinary high-protein eating harms healthy kidneys.3
If you have kidney disease or another condition that affects how your body processes protein, speak to your GP or prescriber before significantly increasing your intake. Your safe range may be different from the general guidance in this article.
When should you seek medical advice?
Speak to your prescriber or GP if:
- You're consistently unable to eat enough to meet your protein target, even with smaller, more frequent meals
- You notice ongoing muscle weakness, hair thinning or slow-healing wounds, which can all be signs of inadequate protein or a wider nutritional shortfall
- You have an existing kidney condition and are considering a significantly higher protein intake
- Nausea or vomiting is severe enough that you cannot keep any food or fluids down
Frequently asked questions
How much protein should you eat a day on Wegovy or Mounjaro?
Most people combining GLP-1 medication with resistance training do well starting around 1.2 to 1.6g of protein per kilogram of body weight a day, building towards the higher end of that range with more consistent training. That's meaningfully higher than the UK general baseline of 0.75g per kilogram.
Is 100g of protein a day enough on Mounjaro?
For many people, yes, particularly at lower body weights or once appetite has settled. As a rough guide, 100g sits within the working range for someone around 65 to 80kg, though your own target depends on your body weight and how much resistance training you're doing.
What foods are high in protein for someone with a reduced appetite?
Protein-dense foods that don't require eating a large volume work well, such as eggs, Greek yoghurt, cottage cheese, chicken, fish, tofu, and lentils. Liquid options like milk, protein shakes, or a lentil-based soup can also be easier to manage than solid food on low-appetite days.
Do protein shakes interfere with Wegovy or Mounjaro?
No. Protein shakes don't interact with either medication. They're simply a convenient way to top up your intake, particularly useful when appetite is low, though they still count towards your daily calorie intake like any other food or drink.
Can too much protein be harmful while taking GLP-1 medication?
For healthy adults with no kidney or liver disease, protein intakes within the ranges discussed in this guide are considered safe. If you have an existing kidney or liver condition, speak to a GP or dietitian before significantly increasing your protein intake.
Does eating more protein actually help prevent muscle loss on semaglutide?
Research presented at the Endocrine Society's 2025 annual meeting found that people using semaglutide who ate more protein experienced less muscle loss than those eating less, alongside resistance training as the other major protective factor.
References
- Look M, et al. Body composition changes during weight reduction with tirzepatide in the SURMOUNT-1 study of adults with obesity or overweight. Diabetes, Obesity and Metabolism. 2025. dom-pubs.onlinelibrary.wiley.com
- British Nutrition Foundation. Nutrition information about protein and plant-based protein. 2026. nutrition.org.uk
- Jäger R, et al. International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition. 2017;14:20. doi:10.1186/s12970-017-0177-8
- Electronic Medicines Compendium. Mounjaro SmPC; Wegovy SmPC. eMC. medicines.org.uk/emc
This article is intended for informational purposes only and does not replace professional medical advice. Always read the patient information leaflet supplied with your medication and speak to a healthcare professional if you have specific concerns.