If you’ve recently started Wegovy, Mounjaro, or another GLP-1 medication, you probably weren’t warned about one particular side effect loudly enough: constipation. It hits most people within the first few weeks, and for some it sticks around far longer than the nausea does.
The good news? Your diet can fix most of it. Not “drink more water” generic advice, but actual, specific GLP-1 diet foods that keep things moving while helping you get the nutrition your body now desperately needs on a reduced appetite.
So what is the GLP-1 diet, really? And which foods belong on your plate versus which ones are making the problem worse?
What Is the GLP-1 Diet?
The GLP-1 diet isn’t a branded meal plan or a fad. It’s simply a way of eating that works with your medication rather than against it. GLP-1 receptor agonists like Wegovy (semaglutide) and Mounjaro (tirzepatide) slow gastric emptying, meaning food sits in your stomach longer. That’s partly why you feel full sooner. But it also means your digestive system is working at a different pace, and the wrong foods can make that painfully obvious.
A solid GLP-1 diet prioritises four things: lean protein to protect muscle mass, fibre to keep your gut moving, healthy fats for satiety and nutrient absorption, and hydration to soften everything in transit. Get those four right, and most of the digestive discomfort eases up within days.
The reason protein matters so much is that GLP-1 medications reduce your overall calorie intake significantly. If you’re eating 800 to 1,200 calories a day instead of your usual 1,800 to 2,200, you can’t afford to fill those calories with empty carbohydrates. Every bite needs to count. Nutritionists working with GLP-1 patients recommend around 1.2 grams of protein per kilogram of body weight daily. For someone weighing 80kg, that’s roughly 96 grams of protein spread across the day.
Your GLP-1 Food List: What to Eat
Here’s a practical GLP food list broken into categories. These are the best foods to eat on GLP-1 medication, chosen specifically because they support digestion, protect lean muscle, and deliver maximum nutrition in smaller portions.
Protein-rich foods
Eggs, chicken breast, turkey mince, white fish (cod, haddock, sea bass), salmon, prawns, Greek yoghurt, cottage cheese, tofu, tempeh, lentils, and black beans. Aim for a palm-sized portion at every meal. If your appetite is very suppressed, a protein shake can bridge the gap, but whole foods should come first when possible.
High-fibre fruits
Raspberries (one cup delivers around 8 grams of fibre), kiwi fruit, pears with the skin on, oranges, cherries, and green bananas. Prunes deserve a special mention here. They contain sorbitol, a natural compound that draws water into the bowel and acts as a gentle, food-based laxative. Two to four prunes a day can make a noticeable difference within 48 hours.
Vegetables that support digestion
Spinach, asparagus, broccoli, Brussels sprouts, courgette, peppers (red, green, yellow), mangetout, sweetcorn, broad beans, artichoke, and aubergine. These are high in both soluble and insoluble fibre. Soluble fibre absorbs water and forms a gel-like consistency that softens stools. Insoluble fibre adds bulk and helps move things through your intestines faster. You want both types working together.
Whole grains and cereals
Porridge oats, brown rice, wholemeal pasta, granary bread, seeded loaves, Weetabix, Bran Flakes, and Shredded Wheat. These are slow-release carbohydrates that won’t spike your blood sugar, and they pack significantly more fibre than their white, refined counterparts. Swapping white bread for a granary loaf alone can add 4 to 6 grams of fibre to your daily intake.
Healthy fats
Avocado, extra virgin olive oil, nuts (almonds, walnuts, pistachios), seeds (flaxseed, chia seeds, pumpkin seeds), and peanut butter. Healthy fats stimulate GLP-1 release naturally and help your body absorb fat-soluble vitamins (A, D, E, K) that you might otherwise miss on a lower-calorie diet. Flaxseed and chia seeds do double duty here because they’re also excellent sources of fibre.
Prebiotic and probiotic foods
Prebiotics feed the beneficial bacteria already living in your gut. Good sources include garlic, onions, leeks, chicory root, and slightly under-ripe bananas. Probiotics introduce new beneficial bacteria. Look for live yoghurt, kefir, sauerkraut, kimchi, and miso. A healthy gut microbiome has been linked to more regular bowel movements, and GLP-1 medications can temporarily disrupt that microbiome as your body adjusts.
GLP-1 Foods to Avoid
Not everything makes the cut. Some foods actively slow digestion further or trigger uncomfortable side effects when combined with GLP-1 medication. Here’s what to limit or cut out entirely.
Fried and greasy foods sit in your stomach even longer when gastric emptying is already delayed. Think chips, fried chicken, battered fish, and takeaway curries swimming in oil. These are the number one trigger for nausea and bloating on GLP-1s, and they contribute to constipation by slowing transit time even further.
Refined carbohydrates and sugary foods like white bread, pastries, biscuits, sugary cereals, and sweets provide almost no fibre. They spike blood sugar, crash it, and leave you with none of the digestive benefits your body needs right now. If you’re only eating 1,000 to 1,200 calories, spending 300 of them on a pastry is a trade your gut will punish you for.
Processed meats such as sausages, bacon, salami, and deli ham are high in sodium and saturated fat, both of which can worsen constipation. High-sodium foods pull water away from your intestines, making stools harder and more difficult to pass.
Carbonated drinks can cause significant bloating and gas when your stomach is emptying more slowly. Fizzy water included. Stick to still water, herbal teas, and diluted squash.
Alcohol dehydrates you, irritates the gut lining, and can interact with the way your medication works. It’s also pure empty calories at a time when every calorie needs nutritional value behind it.
How to Structure Your Eating on a GLP-1
Eating five to six smaller meals throughout the day tends to work better than two or three large ones. When your stomach empties more slowly, a big meal sits there for hours and creates that heavy, bloated, uncomfortable feeling. Smaller portions move through more efficiently.
A simple template for each mini-meal: one palm-sized protein source, one or two fistfuls of vegetables or fruit, and a thumb-sized portion of healthy fat. Add a small serving of whole grains to two or three of those meals. That’s it. No calorie counting required, just a visual plate check.
Hydration is non-negotiable. Aim for 1.5 to 2 litres of water daily, and more if you’re exercising. Fibre without adequate water can actually make constipation worse, because the fibre absorbs moisture and creates bulk that has nowhere to go. Think of fibre as a sponge. Without water, it’s dry and stuck. With water, it moves.
When Diet Alone Isn’t Enough
Sometimes, even with the right GLP-1 diet foods on your plate, constipation persists. That’s normal, especially in the first few months while your body adjusts to the medication. If dietary changes aren’t providing relief after a couple of weeks, over-the-counter laxatives can help. Bulk-forming options like Fybogel (ispaghula husk) are usually the first step. Osmotic laxatives such as Lactulose or Movicol work by drawing water into the bowel. Stimulant laxatives like Senna or Bisacodyl are stronger and best used short-term.
The key is to start gentle and escalate only if needed. And always talk to your prescribing clinician before combining laxatives with your GLP-1 medication. They can rule out other causes and recommend the right approach for your situation.
Regular movement helps too. Even a 20-minute walk after meals stimulates the muscles in your intestinal wall and encourages peristalsis, the wave-like contractions that push food through your digestive tract. You don’t need to run a 10K. Consistency beats intensity here.
The Bottom Line
What is the GLP-1 diet? It’s eating with intention while your medication does its job. Protein to protect your muscles. Fibre to keep your gut moving. Healthy fats for nutrient absorption. Water to tie it all together. And fewer of the processed, fried, sugary foods that slow everything down when your digestive system is already operating in low gear.
Constipation on GLP-1 medication is common, but it doesn’t have to be your new normal. The right food choices, made consistently, can resolve it for most people without needing to reach for laxatives at all.
If you’re looking for personalised guidance on managing side effects while taking Wegovy or Mounjaro, a specialist weight management clinic can help you build a plan that fits your body, your medication dose, and your lifestyle.
Frequently Asked Questions
What is the GLP-1 diet?
The GLP-1 diet is a way of eating designed to complement GLP-1 receptor agonist medications like Wegovy (semaglutide) and Mounjaro (tirzepatide). It focuses on lean protein, high-fibre foods, healthy fats, and adequate hydration to support weight loss, preserve muscle mass, and reduce common side effects like constipation, nausea, and bloating.
What are the best foods to eat on GLP-1 medication?
The best foods to eat on GLP-1 medication include eggs, chicken, fish, Greek yoghurt, lentils, berries, kiwi fruit, leafy greens, broccoli, whole grains like oats and brown rice, avocado, nuts, seeds, and probiotic foods like live yoghurt and kefir. These foods deliver protein, fibre, and essential nutrients in smaller portions that suit a reduced appetite.
What GLP-1 foods should I avoid?
You should avoid or limit fried foods, refined carbohydrates (white bread, pastries, sugary cereals), processed meats, carbonated drinks, and alcohol. These foods can worsen constipation, trigger nausea and bloating, and waste valuable calories when your overall intake is significantly reduced.
Does the GLP-1 diet help with constipation?
Yes. Constipation is one of the most common side effects of GLP-1 medications because they slow gastric emptying. Eating high-fibre foods (fruits, vegetables, whole grains), drinking 1.5 to 2 litres of water daily, and including prebiotic and probiotic foods can significantly improve bowel regularity without medication.
How much protein do I need on a GLP-1 medication?
Most nutritionists recommend approximately 1.2 grams of protein per kilogram of body weight per day when taking GLP-1 medication. For an 80kg person, that’s roughly 96 grams daily. Prioritising protein at every meal helps prevent the muscle loss that can occur when calorie intake drops significantly.