Life on a GLP-1: eating, exercise and injections

What should I eat on a GLP-1?

Smaller meals with protein first. You will eat less, so each bite needs to count for protein, fibre and fluids.

A 2025 advisory from four US nutrition and obesity groups proposes 1.2–1.6 g of protein per kg of body weight a day during weight loss.¹ The everyday minimum for adults is 0.8 g per kg.¹

For a 90 kg (14 st 2 lb) person, that works out to 108–144 g a day.¹ But using your full body weight can overestimate what you need.¹ So the same advisory offers a simpler goal: 80–120 g a day.¹ It also warns against staying at 2 g per kg or more for long.¹ If you have kidney disease, ask your doctor before eating more protein.

Eating the protein part of your plate first helps you finish it before you feel full.¹ The advisory favours beans and lentils, dairy, fish, eggs and chicken. It suggests keeping red and processed meat low.¹

Protein in everyday UK foods

We worked out each serving from the UK's official food tables (McCance and Widdowson's, known as CoFID).² Each line says whether the food is weighed raw, cooked or from a can.

Source: McCance and Widdowson's Composition of Foods Integrated Dataset 2021, protein per 100 g, multiplied up to each serving and rounded to whole grams.²

A worked example: 100 g chicken, 150 g Greek-style yogurt and 200 g baked beans add up to about 43 g of protein.² That is just over half of the 80 g goal.

Smaller meals, fibre and fluids

• Small meals. Vomiting is more likely after a large meal.¹
• If you feel sick: try a small breakfast, then small meals every 3–4 hours.¹
• Fibre, slowly. Go easy on high-fibre food in the first few days. After that, add fibre gradually to prevent constipation.¹
• Fluids. Losing fluids through vomiting or diarrhoea can harm your kidneys.^1,9 The advisory says to drink enough fluids.¹ For alcohol, see Questions people ask.

How do I keep my muscle?

Do strength exercise at least 3 times a week, and eat enough protein. Walking alone protects less muscle than walking plus strength training.¹

Not all the weight you lose is fat. In one semaglutide trial, of every 10 kg (about 22 lb) lost, about 4 kg was "lean mass": muscle and other non-fat tissue. About 2 kg of that was muscle.¹

The 2025 advisory suggests strength training at least 3 times a week, plus at least 150 minutes of moderate activity, like brisk walking.¹ The plan should match your fitness level.¹

What about Christmas, Ramadan and other fasts?

Big meals make vomiting more likely, so take small plates and stop early.¹ Fasting needs a plan, especially if you take insulin or a sulfonylurea (a type of diabetes tablet, such as gliclazide).^10,15

Christmas, parties and big meals

Christmas dinner, office parties, weddings, Eid and Diwali meals all follow the same rules:¹

• Small portions, eaten slowly, with the protein first.¹
• Fewer rich, fried and sweet dishes.¹
• Keep alcohol to a minimum.¹
• You don't have to finish what you're served, or have a second helping to be polite.

If your injection day lands on a big day and you'd rather move it, you can, as long as there are at least 3 days between two doses.^5,6

Ramadan

The main international guidance is the 2021 Ramadan guidelines from the International Diabetes Federation and the Diabetes and Ramadan International Alliance (IDF-DAR).^13,14 UK pharmacy advice from July 2026 builds on them:¹⁵

• GLP‑1 medicines can be used while fasting, if taken on schedule with a doctor's oversight.^13,14 Don't stop without medical advice.¹³
• Finish dose increases first. The UK advice is to complete them at least 4 to 6 weeks before a planned fast, and to put off the next increase if the fast starts soon.¹⁵
• Weekly injections stay on the same day each week. Some people inject after iftar to limit nausea, others after suhoor to stay full through the day.¹⁵
• Wegovy tablets need an empty stomach and a 30-minute wait before eating, so they fit best on waking for suhoor.^7,15
• Watch for constipation and dehydration. Fasting raises the risk of these, and of missing nutrients. Fill the eating window with wholegrains, pulses, fruit, vegetables and enough fluids.¹⁵
• The research is mostly on older GLP‑1 medicines (liraglutide, lixisenatide and exenatide). The 2021 guidelines don't name semaglutide or tirzepatide, and say more research is needed.¹⁴

Other fasts

We found no UK guidance written for GLP‑1 users during other religious fasts, such as Yom Kippur, Lent, Navratri or Karva Chauth. The same UK pharmacy advice applies to any planned fast: finish dose increases weeks before, and plan your fluids.¹⁵

How do I inject, and what if I miss a dose?

Inject once a week, on the same day, into your belly, thigh or upper arm. Use a new needle and a new spot each time.

• Where: just under the skin of the belly, thigh or upper arm.^3,6 For Mounjaro, the back of the upper arm is for someone else to inject.⁶
• When: any time of day, with or without food.^3,6
• Rotate: use a different spot each week.⁶
• Needles: a new needle every time. Don't store the pen with a needle on.¹⁰
• Never share a pen, even with a new needle. It can spread serious infection.¹⁰

Getting rid of needles and pens

• Use a sharps bin. They are available on prescription from your GP, or you can buy one from a pharmacy.²⁰
• When it's full, ask your pharmacy whether it takes sharps bins, or ask your council. Many councils run a free collection you book.^20,21 Arrangements vary by area.
• Never put needles in the household or recycling bin, or in a drinks can or bottle.²⁰ One council linked a rise in needles in household bins to weight-loss pens from both the NHS and online pharmacies.²¹
• Don't recap, bend or break a used needle.²⁰

Missed a dose?

Never take two doses to catch up. The UK labels say to skip a late dose and carry on as normal on your usual day.^3,6 If you've missed more than one dose, ask your doctor before restarting. The Wegovy label says a lower restarting dose should be considered.³

On tablets?

• Wegovy tablets: take one on an empty stomach after at least 8 hours without food, swallowed whole with a sip of water (up to 120 ml). Then wait at least 30 minutes before eating, drinking or taking other tablets. If you miss a day, skip it and take the next one the following day.⁷
• Rybelsus (for type 2 diabetes) is also taken on an empty stomach, followed by a 30-minute wait.¹¹
• Foundayo (orforglipron) can be taken at any time of day with no food or water restrictions, the MHRA says.⁸

How do I store it, and travel with it?

Keep unopened pens in the fridge. Once in use, most can sit outside the fridge for a few weeks, but only below 30 °C.

Store new pens at 2–8 °C, away from the cooling element. Never freeze them, and never use one that has frozen.^3,5,6 Keep the cap on to protect the pen from light.³

From the UK product information. Always follow the leaflet in your own pack.

Travelling. Diabetes UK's advice for insulin, which also needs fridge storage, fits here. Carry it in hand luggage, because the hold gets very cold and bags get lost.¹² A cool bag helps, but don't let the pen touch frozen ice packs.¹² Some airlines ask for a doctor's letter, so carry your prescription.¹²

How do I know if it's working?

Expect a review around 6 months. The NHS yardstick is losing at least 5% of your starting weight.

1. Week 0Start on a low dose. Write down your weight and waist.
2. Every 4 weeksThe dose usually steps up, if side effects allow. If stomach side effects are bad, the next step can wait.^3,6
3. Month 6NICE: consider stopping semaglutide if under 5% has been lost.¹⁶ For tirzepatide, if under 5% has been lost after 6 months on the highest dose you can tolerate, decide whether to carry on.¹⁷
4. After thatRegular reviews, for as long as you take it. On the NHS, Wegovy for weight in a specialist service is for up to 2 years.¹⁶

For a 90 kg (14 st 2 lb) person, 5% is 4.5 kg, about 10 lb. Falling short doesn't mean you failed. Your doctor weighs up the benefits and risks of carrying on.¹⁷ Guide 3 covers the other options.

On the older daily medicine liraglutide (Saxenda), the label is stricter: stop after 12 weeks on the full 3 mg dose if you haven't lost at least 5%.¹⁸ And none of these medicines replaces diet and exercise: NICE recommends them alongside a reduced-calorie diet and more activity.^16,17

What should I keep track of?

Your weight, waist and side effects, and your sugar if you have diabetes. Bring the notes to each review.

• Weight and waist: write them down, so you can compare at your reviews. Guide 1 shows how to measure your waist.
• Blood sugar, if you have diabetes: check before you start and while you take it.⁹ Low sugar can show as dizziness, sweating, shaking, blurred vision, confusion or a fast heartbeat.⁹
• Doctor checks: your heart rate, because your resting pulse can rise on these medicines. Tell your doctor if your heart races while you are resting.⁹ Kidney tests if you've had bad vomiting or diarrhoea.⁹ If you have diabetes, report any change in your eyesight: a fast improvement in blood sugar can briefly worsen diabetic eye disease (retinopathy).⁹
• Side effects and meals: note what you ate before nausea. Patterns help.
• Report side effects to the MHRA's Yellow Card scheme. Anyone can report.¹⁹

What about food noise and family meals?

Many people find the constant thoughts about food go quiet. Some also lose the pleasure of eating, and that can feel strange at family meals.

Studies show less "food noise", less emotional eating and fewer binges on these medicines.¹ But some people miss the joy of food, or of cooking for others.¹ If food has always been how your family shows care, that change can be hard. Talking it through, or seeing a counsellor, can help.¹

Don't skip meals for hours because you aren't hungry. Getting very hungry can bring back cravings for sweets and refined carbs.¹

At home, it helps if the people you eat with know why your plate is smaller. A simple line works: "I'm on a medicine that fills me up fast. I'll have a little of everything."

Questions people ask