As a general guide, many people losing weight on Mounjaro aim for around 1.2 to 1.6g of protein per kilogram of body weight per day to help protect muscle while fat comes off. For someone weighing 90kg, that is roughly 108–144g of protein daily, spread across your meals. Your own target should be confirmed with your prescriber or a dietitian, as it depends on your weight, kidney health and activity level.
Why protein matters more on Mounjaro
Mounjaro (tirzepatide) works by activating two gut-hormone receptors — GLP-1 and GIP — which reduce appetite and slow how quickly your stomach empties. The result is that you naturally eat less and often lose weight steadily.
The challenge is that when you lose weight quickly, some of that loss can come from muscle as well as fat. Eating enough protein, combined with resistance exercise, helps signal to your body to hold on to lean muscle while you lose fat. You can learn more about how the medicine works on our Mounjaro page.
Protein also helps you feel fuller for longer, which complements Mounjaro's appetite-reducing effect and makes it easier to eat well on a smaller overall intake.
How to work out your protein target
A simple, widely used starting point for adults losing weight is 1.2–1.6g of protein per kilogram of body weight per day. Here is how that looks at a few body weights:
| Body weight | At 1.2g/kg | At 1.6g/kg |
|---|---|---|
| 70kg | 84g | 112g |
| 80kg | 96g | 128g |
| 90kg | 108g | 144g |
| 100kg | 120g | 160g |
| 110kg | 132g | 176g |
If you have reduced kidney function, your target may be lower — always check with a healthcare professional before aiming high. Severe kidney impairment is one of the situations where Mounjaro itself may not be suitable, which is why your health is reviewed during your consultation.
Spread it through the day
Your body uses protein most effectively when it is spread across meals rather than eaten all at once. Aiming for roughly 25–40g of protein at each main meal, plus a protein-rich snack if needed, is a practical approach.
This is especially helpful on Mounjaro because your appetite may be smaller. Front-loading protein earlier in the day, when nausea tends to be milder, can make reaching your target easier.
UK food examples and their protein content
Here are approximate protein amounts for everyday UK foods to help you build meals that hit your target:
| Food | Typical portion | Protein (approx.) |
|---|---|---|
| Chicken breast, cooked | 120g | 36g |
| Tinned tuna, drained | 1 small tin (100g) | 25g |
| Salmon fillet, cooked | 120g | 30g |
| Lean beef mince (5% fat), cooked | 100g | 26g |
| Eggs | 2 large | 12g |
| Greek yoghurt (0% fat) | 170g pot | 17g |
| Cottage cheese | 100g | 12g |
| Semi-skimmed milk | 200ml | 7g |
| Tinned chickpeas | 100g drained | 7g |
| Red lentils, cooked | 100g | 9g |
| Tofu, firm | 100g | 13g |
| Reduced-fat cheddar | 30g | 9g |
| Whey protein powder | 1 scoop (30g) | 22g |
A sample day hitting around 120g of protein
- Breakfast: 2 eggs on wholemeal toast + a 170g pot of Greek yoghurt (~29g)
- Lunch: Tinned tuna with mixed beans and salad (~32g)
- Dinner: 120g chicken breast with vegetables and a small portion of rice (~36g)
- Snack: Cottage cheese with a handful of nuts, or a glass of milk (~20g)
If your appetite is very low on higher doses, a protein shake or a yoghurt can be an easy way to top up without feeling overly full.
Practical tips for eating enough protein on Mounjaro
- Eat protein first. With a smaller appetite, put the protein on your plate before the carbohydrates so you get it in even if you fill up quickly.
- Keep easy options to hand. Pre-cooked chicken, tinned fish, eggs, Greek yoghurt and cottage cheese need little effort on days when cooking feels like too much.
- Use softer textures if nausea strikes. Smooth yoghurt, scrambled eggs, soups with added lentils or beans, and shakes are gentler on the stomach.
- Stay hydrated. Adequate fluid supports digestion and can ease constipation, a common Mounjaro side effect.
Don't forget strength training
Protein and resistance exercise work as a pair. Two or three sessions a week of bodyweight exercises, resistance bands or weights give your muscles the stimulus to stay strong while you lose weight. Even gentle, progressive strength work makes a meaningful difference to how much lean mass you keep.
Where Mounjaro fits in
Mounjaro is a prescription-only medicine. In the SURMOUNT-1 trial, participants on the 15mg dose lost on average 22.5% of body weight over 72 weeks, alongside lifestyle support. Individual results vary; not everyone reaches this.
Good nutrition — protein included — is the lifestyle support that helps those results translate into healthier body composition, not just a lower number on the scales. If you are exploring your options, you can compare Mounjaro with the Wegovy injection, the Wegovy Tablet and Foundayo on our treatments overview.
Mounjaro, like all weight-management medicines, is available only after a clinical consultation with a GPhC-registered prescriber who checks it is appropriate for you. You can begin with a free online consultation — a prescription is never guaranteed.
A note on side effects
Common side effects of Mounjaro include nausea, diarrhoea, constipation, vomiting, decreased appetite and fatigue, all of which can affect how much you eat. If you experience side effects, you can report them via the MHRA Yellow Card scheme at https://yellowcard.mhra.gov.uk/.
This article is for information only and is not a substitute for personalised medical advice. Weight-loss medicines are prescription-only, are not suitable for everyone, and are prescribed only after a clinical consultation with a GPhC-registered prescriber. Individual results vary. Always speak to a UK-registered pharmacist or doctor before starting or changing any prescription medication.
