If you're taking Mounjaro or Wegovy, you may be finding it harder to hit your daily protein targets. As both medications suppress appetite, you tend to find yourself eating smaller portions, which can make it easy to fall behind on your intake without realising it.
Getting sufficient protein is especially important while taking GLP-1 medications because it's one of the few things within your control that helps protect 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 help hit your target even when your appetite is low.
Why protein intake matters more on a GLP-1 medication
Mounjaro (tirzepatide) and Wegovy (semaglutide) work by mimicking gut hormones that reduce appetite and slow gastric emptying, which is why meals feel filling much sooner than before treatment. Smaller meals mean fewer total calories, and protein generally tends to be more satiating and takes longer to digest than other macronutrients, which can further reduce the amount you're eating.
This matters because any calorie deficit, whether from diet, medication or both, causes the body to break down some muscle tissue alongside fat. A dual-energy X-ray absorptiometry (DXA) substudy of the SURMOUNT-1 trial found that around a quarter of the weight lost on tirzepatide came from lean mass, with the remaining three quarters from fat.1 We've covered the full picture in our article on whether Mounjaro or Wegovy causes muscle loss, and alongside resistance training, adequate protein intake is the other main factor that keeps the muscle to fat ratio working in your favour.
Muscle isn't just about strength or appearance. It plays a direct role in your resting metabolic rate, meaning the calories your body burns simply keeping itself running, and it supports blood sugar regulation and everyday functional movement such as climbing stairs or carrying shopping. Losing a disproportionate amount of muscle alongside fat can leave you lighter on the scale but weaker and more prone to regaining 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 per day, which works out at around 56g a day for a 75kg adult.2 That figure is designed to prevent deficiency in a generally healthy, sedentary population, and it isn't intended to protect muscle during active weight loss.
For anyone in a calorie deficit, whether from a GLP-1 medication, 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 per day for people restricting calories while trying to preserve muscle, with intakes towards the higher end of that range offering more protection for those who are 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 daily
- If you weigh 75kg, that's roughly 90g to 120g of protein daily
- If you weigh 90kg, that's roughly 108g to 144g of protein daily
These are starting points rather than 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 significantly over the course of 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 the body needs, including leucine, which plays a key role in triggering muscle protein synthesis. 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 a single source, helps close that gap.
This doesn't mean you need to eat meat at every meal. Combining sources, such as beans with rice or hummus with wholegrain bread, provides a more complete amino acid profile over the course of a day, even if any single meal isn't perfectly balanced on its own.
Practical ways to hit your protein target with a smaller appetite
Eating enough protein when you feel full quickly means changing how you eat, not only what you eat:
- Eat protein first - start each meal with the protein portion before vegetables or carbohydrates, 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 trying to eat one large portion at dinner
- Use a protein shake as 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 targets than a full traditional plate, and hitting several smaller targets across the day adds up
Should you use a protein supplement?
A protein shake or bar isn't essential, but it can be a genuinely useful tool if your appetite makes whole food difficult to eat in sufficient quantity. Whey protein is well absorbed and convenient, and most standard shakes provide 20g to 30g of protein in a small volume, which is often easier to manage than an equivalent amount of solid food. If you're vegetarian, vegan or avoid dairy, pea, soy and other plant-based protein powders are reasonable alternatives, though it's worth checking the label, as some plant blends provide less protein per scoop than whey.
Supplements work best as a way to close a gap rather than as a replacement for eating properly across the day. If you find you're relying on shakes for the majority of your protein intake because solid food consistently feels too much, it's worth mentioning this to your prescriber, since it may be a sign that your dose or titration schedule needs reviewing.
Managing protein intake on higher-nausea days
Nausea is one of the most commonly reported side effects of both medications, particularly in the days following a dose increase, and it often makes protein-rich foods feel unappealing before anything else.4 On days when nausea is more noticeable:
- Choose cold or room-temperature protein sources, such as yoghurt, cottage cheese or a protein shake, which tend to be better tolerated than hot, rich meals
- Eat smaller amounts more frequently rather than trying to finish a full meal in one sitting
- Avoid very high-fat protein sources temporarily, since these can be slower to digest and may worsen nausea
- Prioritise getting some protein in over hitting your exact target - a partial amount most days beats an empty plate
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, and the evidence doesn't support the idea that ordinary high-protein eating harms healthy kidneys.3 If you have kidney disease or another condition affecting how your body processes protein, speak to your GP or prescriber before significantly increasing your intake, since 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.