How to Eat Well on GLP-1 Medication: A Dietitian's Guide
If you're taking Mounjaro or Wegovy, you've probably noticed the biggest change straight away: you're just not that hungry. Portions shrink, snacking fades and the constant "food noise" goes quiet.
That's the medication doing its job. But here's what many people don't realise: when you're eating less, what you eat matters more, not less. Every meal has to work harder to give your body the protein, fibre, vitamins and minerals it needs.
Get it right and you'll feel better, keep more of your muscle and give yourself the best chance of keeping the weight off long term. Get it wrong and you may feel tired, constipated and run down, and lose more muscle than you'd like.
As a registered dietitian, I've supported thousands of people with their eating. Here's how to eat well on a GLP-1 medication, in plain, practical terms.
1. Put protein first, at every meal to eat well on GLP-1 medication
When weight comes off quickly, some of it is muscle rather than fat. Muscle keeps you strong, supports your metabolism and helps you maintain your weight later on. Protein is your best protection.
Eat protein first. If you fill up after a few mouthfuls, make sure those mouthfuls count.
Aim for a palm-sized portion at every meal. That's roughly 20–30g of protein. Spreading it across the day works better than one big serving.
Choose easy wins: eggs, Greek yoghurt, skyr, cottage cheese, chicken, fish, tofu, tempeh, beans, lentils and milk.
Pair it with strength exercise. Two or three sessions a week, using bodyweight, bands or weights, tells your body to hold on to muscle.
2. Build a smaller, smarter plate
You don't need a special diet. You need a plate that fits your new appetite:
Half: protein
A quarter: vegetables or salad
A quarter: wholegrain carbs, such as oats, brown rice, wholemeal bread or potatoes with skins
Use a smaller plate, eat slowly and stop at the first sign of fullness. On GLP-1s, "comfortably full" arrives sooner and "overfull" can quickly turn into nausea.
3. Don't forget fibre
Constipation is one of the most common GLP-1 side effects, and low fibre makes it worse. As portions shrink, fibre often drops without you noticing.
Add it gradually: oats, beans, lentils, vegetables, fruit, wholegrains, chia or ground flaxseed.
Two kiwis a day is a simple, well-researched option for keeping things moving.
Keep a gentle daily walk in your routine. Movement helps your gut too.
4. Drink more than you think you need
GLP-1s can dull thirst as well as hunger, and dehydration can leave you tired, dizzy and constipated.
Aim for 6–8 glasses of fluid a day, more in hot weather or when you're active.
Sip between meals rather than drinking a lot with food, which can make you feel fuller and queasier.
Water, milk, tea, coffee and sugar-free drinks all count.
5. Make every bite nutrient-rich
Eating less overall means less room for foods that offer little nutrition. That doesn't mean banning treats. It means prioritising:
Colourful fruit and veg for vitamins, minerals and fibre
Calcium-rich foods such as dairy or fortified alternatives, to protect your bones while you lose weight
Iron-rich foods such as red meat, beans, lentils and fortified cereals, to help with energy
Vitamin D: UK guidance is for everyone to consider a 10 microgram supplement in autumn and winter
Go easy on alcohol. It adds calories with no nutrition, can make side effects worse, and hits harder when you're eating less.
What a good day of eating can look like
This isn't a plan to follow exactly, just an example of how small meals can still cover the basics:
Meal | Example | Why it works |
Breakfast | Greek yoghurt with berries, oats and a sprinkle of ground flax | Protein, fibre and calcium in a few spoonfuls |
Lunch | Wholemeal wrap with chicken or hummus, plus salad | Protein first, with easy fibre |
Snack | Two kiwis, or a glass of milk | Fibre, or protein and fluid |
Dinner | Salmon or tofu, roasted veg and a small portion of new potatoes | Protein, colour and slow-release carbs |
Low-appetite day | Soup with lentils, eggs on toast, or a protein smoothie | Gentle and still nourishing |
Eating around side effects
Nausea: eat smaller meals, eat slowly and go easy on fatty or fried foods, which stay in the stomach longest. Cool, bland foods such as toast, crackers, yoghurt and rice are often easier on bad days.
Reflux: avoid eating within about three hours of bed, and cut back on fizzy drinks, alcohol and very spicy food.
Tiredness: this is often a sign you're eating or drinking too little. Check fluids and protein first.
After a dose increase: side effects often return for a week or two, so plan simpler meals and keep easy protein foods in.
If you have severe or persistent stomach pain, vomiting that stops you keeping fluids down, or signs of dehydration, contact your prescriber or call NHS 111.
You don't have to work this out alone. My free GLP-1 support programme gives you a month of dietitian-led guidance on exactly this: what to eat, how to manage side effects and how to protect your muscle. Join free for your first month →
Think beyond the jab
GLP-1 medications are powerful, but they're not designed to do the job on their own. In a major trial of tirzepatide (Mounjaro), people who stopped treatment regained an average of 14% of their body weight within a year, while those who continued kept losing.
That doesn't mean regain is inevitable. It means the habits you build while you're on the medication are what protect you after it. The people who do best:
eat protein at every meal
keep up strength exercise
stick to regular, planned meals rather than grazing
learn the difference between real hunger and habit, boredom or stress
plan when and how to stop with their prescriber, rather than just running out
These habits are much easier to build with support than on your own.
Get a free month of dietitian-led support
My GLP-1 support programme is designed for anyone taking Mounjaro or Wegovy who wants to feel well, protect their muscle and set themselves up for the long term.
Your first month is completely free. You'll get practical, evidence-based guidance from a registered dietitian on what to eat, how to handle side effects and dose increases, and how to build habits that last.
Charlotte Turner-Murthy is a Registered Dietitian (HCPC) and Registered Nutritionist with over 15,000 consultations' experience. This article is general information and doesn't replace advice from your prescriber or GP.
