Key dietary principles on GLP-1 medication
- Protein first: Aim for 1.2–1.5 g per kg of body weight daily to preserve lean muscle mass
- Small, frequent meals: 4–6 smaller portions rather than 3 large meals
- Hydration: At least 1.5–2 litres of fluid daily, sipped between meals
- Nutrient density: Prioritise vitamins and minerals as total food intake decreases
- Fibre balance: Adequate fibre for gut health, but not so much it worsens nausea
Why diet matters more on GLP-1 medication
GLP-1 receptor agonists such as Ozempic, Wegovy and Mounjaro work partly by reducing appetite and slowing gastric emptying. Whilst this produces significant weight loss, it also means you eat considerably less food overall. According to NHS guidelines and the British Dietetic Association (BDA), this reduced intake makes the nutritional quality of every meal more important than ever.
Without careful dietary planning, patients on GLP-1 medication risk losing lean muscle mass alongside fat, developing micronutrient deficiencies and experiencing worsened gastrointestinal side effects. A well-structured eating plan helps maximise fat loss, preserve muscle, maintain energy levels and reduce common side effects such as nausea and constipation.
Protein: your most important macronutrient
Protein preservation is the single most critical dietary consideration when taking GLP-1 medication. Research published in The Lancet and the STEP clinical trial programme has shown that approximately 25–40 per cent of total weight lost on semaglutide and tirzepatide can come from lean body mass rather than fat, unless adequate protein intake is maintained.
How much protein do you need?
The British Dietetic Association recommends a minimum protein intake of 1.2 g per kilogram of body weight per day for patients on weight loss medication. Many specialist dietitians suggest aiming for 1.5 g/kg, particularly during the active weight loss phase. For a person weighing 90 kg, this equates to 108–135 g of protein daily.
Best protein sources
- Lean poultry: Chicken breast, turkey mince (approximately 31 g protein per 100 g)
- Fish and seafood: Salmon, cod, prawns, tinned tuna (20–25 g per 100 g)
- Eggs: 6 g protein per egg; versatile and easy to digest
- Greek yoghurt: 10 g protein per 100 g; also provides probiotics
- Pulses: Lentils, chickpeas, beans (7–9 g per 100 g cooked)
- Tofu and tempeh: 12–19 g per 100 g; suitable for vegetarians and vegans
- Cottage cheese: 11 g per 100 g; low in fat and gentle on the stomach
Practical tip: Eat your protein portion first at every meal. When appetite is reduced, you may not finish everything on your plate, so starting with protein ensures you meet your targets even if you cannot eat the full meal.
Foods to prioritise
Beyond protein, focus on nutrient-dense foods that provide maximum nutritional value per calorie.
- Non-starchy vegetables: Broccoli, spinach, courgette, peppers, green beans — rich in vitamins, minerals and fibre
- Complex carbohydrates: Sweet potatoes, brown rice, oats, wholegrain bread — sustained energy release
- Healthy fats: Avocado, olive oil, nuts, seeds — essential for hormone function and nutrient absorption
- Fruits: Berries, apples, pears — lower in sugar, high in fibre and antioxidants
- Fermented foods: Natural yoghurt, kefir, sauerkraut — support gut microbiome health
Foods to avoid or limit
Certain foods are more likely to trigger or worsen GLP-1 side effects, particularly nausea, bloating and reflux. Consider reducing or avoiding the following:
- High-fat fried foods: Chips, fried chicken, doughnuts — slow gastric emptying further and worsen nausea
- Very sugary foods: Sweets, cakes, biscuits, sugary drinks — provide empty calories and can cause dumping syndrome
- Highly processed foods: Ready meals, crisps, processed meats — low nutrient density
- Carbonated drinks: Can increase bloating and abdominal discomfort
- Alcohol: Increases hypoglycaemia risk (especially with Ozempic for diabetes), provides empty calories and worsens GI symptoms
- Very spicy foods: May aggravate nausea and reflux during dose escalation
- Large portions of raw vegetables: Can be difficult to digest; lightly cook vegetables instead
Managing nausea through diet
Nausea is the most commonly reported side effect of GLP-1 medications, particularly during dose escalation. The following dietary strategies can help reduce its severity:
- Eat small, frequent meals: 5–6 mini-meals rather than 3 large ones reduce stomach distension
- Avoid lying down after eating: Stay upright for at least 30 minutes after meals
- Eat slowly: Allow 20–30 minutes per meal; chew food thoroughly
- Sip fluids between meals: Avoid drinking large amounts with food
- Try ginger: Ginger tea, ginger biscuits or crystallised ginger have evidence-based anti-nausea properties
- Choose bland foods when nauseous: Toast, crackers, plain rice, bananas and boiled potatoes are generally well tolerated
- Keep food cool or room temperature: Strong food smells can trigger nausea; cold meals may be better tolerated
When to seek help: If nausea is persistent and prevents you from eating or drinking adequately for more than 48 hours, contact your prescribing clinician. Persistent vomiting may require a dose reduction or temporary pause in treatment. See our full side effects guide for more information.
Sample weekly meal plan
The following plan provides approximately 1,200–1,500 kcal and 100–130 g of protein per day. Adjust portions to suit your individual calorie needs and appetite. All ingredients are readily available in UK supermarkets.
Monday
Breakfast: Greek yoghurt (150 g) with blueberries and a tablespoon of flaxseed
Lunch: Grilled chicken breast (120 g) with roasted courgette, peppers and quinoa
Dinner: Baked salmon fillet with steamed broccoli and sweet potato
Snack: Cottage cheese (100 g) with cucumber sticks
Tuesday
Breakfast: Two scrambled eggs on one slice of wholegrain toast
Lunch: Lentil soup (home-made or shop-bought) with a small wholemeal roll
Dinner: Turkey mince stir-fry with mixed vegetables and brown rice
Snack: Small handful of almonds (25 g)
Wednesday
Breakfast: Overnight oats (40 g oats, 150 ml milk, chia seeds, sliced banana)
Lunch: Tinned tuna (120 g) mixed with cannellini beans, cherry tomatoes and olive oil dressing
Dinner: Chicken thigh baked with lemon, served with green beans and new potatoes
Snack: Natural yoghurt with a drizzle of honey
Thursday
Breakfast: Protein smoothie (milk, banana, 30 g protein powder, tablespoon of peanut butter)
Lunch: Prawn and avocado salad with mixed leaves
Dinner: Lean beef mince bolognese with wholewheat spaghetti
Snack: Two oatcakes with cottage cheese
Friday
Breakfast: Two poached eggs with half an avocado and cherry tomatoes
Lunch: Chicken and vegetable wrap (wholemeal tortilla)
Dinner: Baked cod with roasted Mediterranean vegetables and couscous
Snack: Apple slices with a tablespoon of almond butter
Weekend
Follow a similar pattern using the protein sources and vegetables listed above. Batch-cooking on Sunday can simplify the week ahead. Aim for at least 25–30 g of protein at each main meal.
Supplements to consider
Because GLP-1 medications reduce overall food intake, certain micronutrient gaps may develop. The NHS and BNF recommend monitoring for the following:
- Vitamin D: PHE recommends 10 µg daily for all UK adults, especially important during weight loss
- Vitamin B12: Particularly relevant if also taking metformin, which can reduce B12 absorption
- Iron: Monitor if menstruating or if dietary intake of red meat is low
- Calcium: Important for bone health during rapid weight loss
- Omega-3 fatty acids: If oily fish intake is less than two portions per week
- A daily multivitamin: A practical option to cover general micronutrient needs
Important: Speak to your GP or pharmacist before starting any supplements, particularly if you take other medications. Some supplements can interact with prescription drugs.
Hydration guidelines
Adequate hydration is essential on GLP-1 medication, particularly because nausea and reduced appetite often lead to decreased fluid intake. Dehydration can worsen constipation, fatigue and dizziness.
- Aim for 1.5–2 litres of fluid daily (water, herbal teas, diluted squash)
- Sip throughout the day rather than drinking large volumes at once
- Avoid drinking large amounts during meals, as this can increase feelings of fullness and nausea
- Monitor urine colour: pale straw indicates adequate hydration
Diet tips for each medication
| Medication | Key dietary consideration |
|---|---|
| Ozempic | If prescribed for type 2 diabetes, coordinate carbohydrate intake with blood glucose monitoring. Avoid skipping meals to reduce hypoglycaemia risk. |
| Wegovy | Higher dose semaglutide (2.4 mg) may cause more pronounced appetite suppression. Meal prepping ensures you eat even when appetite is very low. |
| Mounjaro | Dual GIP/GLP-1 action may affect glucose metabolism differently. Some patients report food aversions; keep a variety of protein sources available. |
When to see a dietitian
Consider asking your GP for a referral to an NHS dietitian or seeking a private registered dietitian (check the BDA website) if you:
- Are losing weight very rapidly (more than 1 kg per week sustained)
- Struggle to eat enough protein despite trying the strategies above
- Have a pre-existing condition such as coeliac disease, inflammatory bowel disease or an eating disorder
- Experience persistent gastrointestinal symptoms that do not improve with dietary adjustments
- Are vegetarian or vegan and need help meeting protein targets
Frequently asked questions
Can I follow a keto diet on GLP-1 medication?
A strict ketogenic diet is generally not recommended alongside GLP-1 medications. The very high fat content can worsen nausea and slow gastric emptying further. A moderate low-carbohydrate approach with adequate protein is a better option. Discuss any restrictive dietary plans with your prescribing clinician.
Should I count calories on Ozempic or Wegovy?
Rigid calorie counting is not typically necessary, as the appetite-suppressing effect of GLP-1 medication naturally reduces intake. However, tracking protein intake (using a free app such as MyFitnessPal) can help ensure you meet your daily targets. Focus on food quality rather than calorie restriction.
Is intermittent fasting safe with GLP-1 medication?
Intermittent fasting is generally not recommended alongside GLP-1 treatment, particularly for patients with type 2 diabetes who are at risk of hypoglycaemia. The medication already reduces appetite significantly, and adding fasting can make it difficult to consume adequate protein and nutrients. Speak to your clinician before combining fasting with GLP-1 therapy.