Protein on Mounjaro or Wegovy: how to protect muscle when you are barely hungry
Short answer: When a GLP-1 cuts your appetite, protein is often the first thing to fall short, and some of the weight you lose can come from muscle rather than fat. Many dietitians suggest people losing weight aim for roughly 1.2 to 1.6 g of protein per kilogram of body weight a day, eaten first at each meal, alongside some strength training. Your prescriber or a dietitian can give you a figure that suits you. Then the job is simply knowing, each day, whether you got there.
Why protein becomes a problem on a GLP-1
The same thing that makes Mounjaro, Zepbound, Wegovy and Ozempic work also makes eating properly harder. Food noise goes quiet, portions shrink and a whole day can pass on a yoghurt and half a sandwich. People describe it in reviews as simply forgetting to eat.
Lower intake is the point, but the mix matters. In the large semaglutide and tirzepatide trials, body scans showed that a meaningful share of the weight lost was lean mass, which includes muscle. Some loss of lean mass happens with any significant weight loss. The worry is losing more than you need to, because muscle helps with strength, balance, blood sugar and keeping the weight off later.
Protein and resistance exercise are the two levers people have. Neither needs to be complicated.
How much protein do people aim for?
There is no single number that fits everyone, and kidney disease or other conditions can change the answer, so this is one to check with your prescriber or a dietitian. As a reference point, the figure commonly quoted for adults losing weight is around 1.2 to 1.6 g per kilogram of body weight per day, compared with about 0.75 g per kilogram in general UK guidance for adults.
| Body weight | At 1.2 g/kg | At 1.6 g/kg |
|---|---|---|
| 70 kg (11 st) | 84 g | 112 g |
| 90 kg (14 st 2 lb) | 108 g | 144 g |
| 110 kg (17 st 5 lb) | 132 g | 176 g |
Some clinicians work from a goal or adjusted body weight rather than current weight for people with a lot to lose, which gives a lower target. If a number looks impossible on your current appetite, that is a sign to ask for a personal target rather than force it.
Ways to get protein in when you are not hungry
- Protein first. Eat the protein part of a meal before the rest, while you still have room.
- Spread it out. Three or four smaller hits of 20 to 30 g sit better than one big plate, especially in the first days after a dose when nausea is most likely.
- Lean on dense, soft foods. Greek yoghurt or skyr, cottage cheese, eggs, fish, chicken, tofu, lentils and milk-based drinks give a lot of protein for a small volume.
- Keep a fallback. A ready-made protein shake or high-protein yoghurt in the fridge covers the days when cooking feels like too much.
- Pair it with strength work. Two or three short sessions a week of weights, resistance bands or bodyweight exercises give the protein a reason to go to muscle.
Why tracking protein is harder than it sounds
Most people do not need a full calorie diary on a GLP-1, and many find one miserable. But without any record, protein is easy to overestimate. A day that felt fine often adds up to 50 or 60 g. The useful habit is small: a running protein total for today, checked against your own target, with nothing else to fill in.
How PepLevel handles it
PepLevel has a deliberately simple protein tracker. You set your own daily goal (the app never works one out for you), then log grams with a tap on a quick amount or by typing a number. The Protein tile on Today shows your running total, so a glance tells you whether you need a yoghurt before bed.
If you already log food in MyFitnessPal, Cronometer or another app that writes to Apple Health, turn on protein import and those grams count towards the day without retyping. The log shows what came from Health and what you added in PepLevel, so double counting is easy to spot and remove. If it helps, add a protein check-in at a time you choose, such as early evening. It is a gentle reminder, never a scold.
Because your weight trend, doses and side effects sit in the same app, you can see whether the days you struggled to eat line up with the first days after a dose, which is worth mentioning at your next review.
Common questions
How much protein should I eat on Mounjaro?
There is no official Mounjaro protein target. A figure commonly quoted for adults losing weight is around 1.2 to 1.6 g per kilogram of body weight a day, but your prescriber or a dietitian can give you a number that fits your health and appetite.
Do you lose muscle on GLP-1 medication?
Some of the weight lost on any large weight-loss treatment is lean mass, and trials of semaglutide and tirzepatide showed this too. Eating enough protein and doing regular strength exercise are the two main ways people try to keep muscle loss down.
Do I need to count calories to track protein?
No. You can track protein on its own as a daily total against a goal. PepLevel only asks for grams of protein, and it can pull protein in from a food app through Apple Health if you already use one.
Protein, without a food diary
Log grams in a tap against your own goal, or pull them in from Apple Health. Coming soon to the App Store.
Get PepLevelMedical disclaimer: this guide is general information, not medical advice. Always follow your prescriber's instructions, and ask them, your pharmacist or NHS 111 if you are unsure about anything. PepLevel is a logging and reminder tool only.