What to Eat on GLP-1: A UK Food Guide for Semaglutide and Tirzepatide Users

If you have recently started on semaglutide (Wegovy, Ozempic) or tirzepatide (Mounjaro), you will have noticed something remarkable: food just does not interest you the way it used to. That two o'clock craving for a Greggs sausage roll? Gone. The Sunday evening urge to order a Deliveroo? Barely there.

That appetite suppression is precisely how GLP-1 medications work. They mimic a hormone your gut already produces, slowing gastric emptying and telling your brain you are satisfied with far less food. The clinical results are striking. In the STEP 1 trial, semaglutide delivered roughly 15% body weight reduction compared to about 5-7% from diet and exercise alone. Tirzepatide, which targets both GLP-1 and GIP receptors, has shown even more impressive figures.

But here is the problem nobody is talking about clearly enough.

When your appetite drops by 70-80% and you are eating perhaps half the food you used to, every single bite carries far more weight than it did before. If those reduced calories come from nutrient-poor choices, you are not just missing out on vitamins. You are actively losing muscle.

Research presented at ENDO 2025 confirmed what many clinicians already suspected: approximately 40% of the weight lost on semaglutide comes from lean mass, including muscle. Being older, female, or eating insufficient protein makes this significantly worse. And here is the critical finding: losing too much muscle actually reduces the blood sugar benefits the medication is supposed to deliver.

So the real question for anyone on a GLP-1 in the UK right now is not "how do I eat less?" The medication handles that. The question is: "How do I make what I do eat count?"

The protein problem

Let me be specific about this, because vague advice like "eat more protein" helps nobody.

The standard Recommended Dietary Allowance for protein is 0.8g per kilogram of body weight per day. That figure was designed for sedentary adults maintaining their current weight. It was never intended for people undergoing significant, rapid weight loss on pharmacotherapy.

For GLP-1 users, the emerging consensus from multiple research groups, including a joint advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, and the Obesity Society, is considerably higher: 1.2 to 1.6g per kilogram per day. Some researchers are pushing towards a simpler absolute target of 80-120g of protein daily.

That sounds straightforward until you factor in the appetite suppression. A recent cross-sectional study found that only 43% of GLP-1 users were hitting even the 1.2g/kg threshold. Just 10% reached 1.6g/kg. Most people on these medications think they are eating enough protein. They are not.

Here is what 25-30g of protein actually looks like using foods you can buy in any UK supermarket this week:

Fage Total 0% Greek Yoghurt (200g pot): About 20g of protein. Add a tablespoon of mixed seeds and you are at 25g. This is an excellent breakfast option because it is easy to eat even when your appetite is low, and the thick texture means it sits well in a slow-emptying stomach.

Two large eggs scrambled with 30g smoked salmon: Around 22g of protein. Quick, requires minimal appetite, and the healthy fats from the salmon support absorption of fat-soluble vitamins you might be deficient in.

Aldi Everyday Essentials chicken breast (150g cooked): 46g of protein. Even eating half gives you a solid 23g serving. Roast a batch on Sunday and slice it through the week.

A tin of Princes tuna in spring water (145g, drained): About 30g of protein. On two Warburtons seeded thins, that is a complete lunch with minimal preparation.

M&S Plant Kitchen Marinated Tofu (225g pack, half): Roughly 18g of protein. Combined with some edamame beans, you are well above 25g.

The pattern to notice here: protein first, at every meal. Not because carbohydrates or fats are bad, but because when you can only eat a fraction of what you used to, protein is the macronutrient your body cannot afford to miss.

What is actually happening when you eat less

When your calorie intake drops substantially, your body does not selectively burn fat. It pulls energy and amino acids from wherever it can, including skeletal muscle. This is not a design flaw. It is a survival mechanism that made perfect sense when food scarcity meant genuine starvation.

The way to counteract this is twofold. First, consume enough protein so your body has the amino acids it needs without breaking down muscle tissue to get them. Second, give your muscles a reason to stick around by using them. Resistance training, even twice a week, sends a powerful signal that your body needs to maintain its muscle mass.

A case series published in 2025 found that patients who combined their GLP-1 medication with consistent resistance training and protein intake of 1.6-2.3g per kg of fat-free mass per day achieved minimal lean mass loss, and some actually gained muscle during treatment. The medication handled the fat loss. The protein and exercise handled the muscle preservation.

Foods that work hard for GLP-1 users

Beyond protein, there are several categories of food that become particularly valuable when your total intake is reduced.

Nutrient-dense whole foods. This is not a platitude. When you are eating 1,200 calories instead of 2,000, a Mars bar at 228 calories represents nearly 20% of your daily intake for almost zero nutritional return. The same calories from a salmon fillet with steamed broccoli delivers protein, omega-3 fatty acids, vitamin D, calcium, iron, and fibre. The gap between nutrient-rich and nutrient-poor choices widens enormously when your eating window narrows.

Fermented foods. Kefir, natural yoghurt, sauerkraut, and kimchi. Your gut microbiome is adapting to dramatic changes in food volume and composition. Professor Tim Spector's research at ZOE has consistently shown that fermented foods reduce inflammatory markers and support microbiome diversity. When your digestive system is being slowed by a GLP-1, giving it beneficial bacteria is not optional. It is maintenance.

Foods rich in fibre. Constipation is one of the most common side effects of GLP-1 medications, because slower gastric emptying means everything moves more slowly through your digestive tract. Oats, chia seeds, ground flaxseed, and vegetables like broccoli, carrots, and courgettes help keep things moving. Aim for 25-30g of fibre daily, but increase gradually. Adding too much fibre too quickly on a GLP-1 is a recipe for painful bloating.

Calcium and vitamin D sources. Rapid weight loss, regardless of the method, is associated with bone density reduction. A 2024 randomised trial found that GLP-1 therapy alone decreased bone mineral density, while combining it with exercise preserved it. Beyond exercise, ensure you are getting adequate calcium (dairy, fortified plant milks, sardines, green vegetables) and vitamin D (oily fish, eggs, and likely a supplement given the UK's latitude).

Foods to limit or avoid

Ultra-processed foods high in sugar. Not because they are forbidden, but because they represent a terrible return on your limited calorie budget. A 330ml can of Coca-Cola is 139 calories of pure sugar with no protein, no fibre, no micronutrients. On a GLP-1, that is not a treat. It is a waste.

High-fat fried foods. Many GLP-1 users report that fatty foods dramatically worsen nausea, especially in the first weeks of treatment. Chips, battered fish, pastries, and creamy sauces can sit like lead in a stomach that is already emptying slowly. This varies between individuals, but if you are experiencing nausea, reducing fat content per meal is the first thing to try.

Alcohol. Beyond the obvious calorie issue (a large glass of wine is 230 calories with negligible nutrition), alcohol on a GLP-1 can cause more pronounced intoxication because your stomach is processing everything more slowly. Several clinicians have reported patients experiencing far stronger effects from their usual amount of alcohol. Proceed with genuine caution.

A practical UK meal framework

Rather than prescribing a rigid meal plan, here is a framework that works within the appetite constraints of GLP-1 treatment:

Breakfast (aim for 25-30g protein): Greek yoghurt with seeds and berries. Or scrambled eggs with smoked salmon. Or a protein smoothie if solid food does not appeal in the morning. Many people on GLP-1s find that liquid meals are easier to tolerate when nausea peaks.

Lunch (aim for 25-30g protein): Tinned fish on seeded crackers with a side salad. Or leftover roast chicken with roasted vegetables. Or a lentil and vegetable soup with a chunk of sourdough.

Dinner (aim for 25-30g protein): Grilled salmon or chicken thighs with sweet potato and steamed greens. Or a prawn stir-fry with brown rice and pak choi. Or a bean chilli with brown rice.

If you can only eat twice a day: That is absolutely fine. Many GLP-1 users find three meals impossible. If that is you, make each meal 35-40g of protein and do not stress about eating patterns that no longer fit your appetite.

How MyFoodFit scores differently for GLP-1 users

This is where most food apps fall short. Yuka gives every product the same score regardless of who is eating it. Nutri-Score applies a single letter grade. Neither system knows or cares whether you are on semaglutide.

MyFoodFit runs a dedicated GLP-1 profile that fundamentally changes how products are evaluated. Protein-dense foods score higher because your body needs them more urgently. A pot of Fage Total Greek yoghurt, which might score moderately for a general user, scores significantly higher for someone on a GLP-1 because of its exceptional protein-to-calorie ratio.

Conversely, low-protein ultra-processed foods score lower. Not just because they are processed, but because for someone with severely reduced appetite, consuming a product that delivers empty calories at the expense of muscle-preserving protein is actively harmful.

The app applies 40 different dietary profiles simultaneously, so if you are on a GLP-1 and also managing, say, IBS or a nut allergy, those constraints layer on top. You get a single score that reflects your actual situation, not a generic population average.

Scan any product in any UK supermarket and you will see within seconds whether it deserves a place in your reduced calorie budget.

The bottom line

GLP-1 medications are remarkable tools. NICE has expanded access to both semaglutide and tirzepatide in the UK precisely because the evidence for their effectiveness is strong. NICE has been progressively widening eligibility for GLP-1 receptor agonists in type 2 diabetes management, reflecting their cardiovascular and renal benefits.

But the medication is only part of the equation. What you eat on a GLP-1 matters more, not less, than what you ate before. Every bite needs to be working for you.

Prioritise protein at every meal. Eat whole foods that deliver genuine nutrition. Include fermented foods to support your gut. Move your body, especially with resistance training. And accept that your relationship with food has fundamentally changed. That change can be the foundation for extraordinary long-term health, provided you build on it wisely.

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This content is for information only and does not replace medical advice. If you are taking or considering GLP-1 medications, consult your GP or specialist weight management team.