Short answer: Eat small, regular meals and stop when you feel comfortably full. Eat a protein food first at each meal and pair it with strength training to help protect muscle. Add fiber gradually, sip fluids through the day, and go easy on fried, greasy food and alcohol, which can make nausea worse. Don’t let a low appetite turn into skipped meals, and ask your prescriber or a registered dietitian what fits you.
GLP-1 medicines such as semaglutide, tirzepatide and liraglutide are used to manage type 2 diabetes or to treat obesity. The NHS explains that semaglutide reduces appetite, helps you feel fuller for longer and slows digestion. With less food, each meal has to do more.
This is general information about food only; which medicine, doses, and starting or stopping are decisions for you and your prescriber. If you have diabetes, kidney problems or a history of an eating disorder, or are pregnant, planning a pregnancy or breastfeeding, talk to your prescriber or a registered dietitian first. The advice below draws on NHS patient information and a 2025 joint advisory from four US medical and nutrition societies.
How to eat when your appetite is small
The joint advisory notes that vomiting is more likely after large meals, and that nausea often shows up in the morning or after long stretches without food.
- Serve smaller portions. Start with less than you used to and go back only if you are still hungry. See how to estimate portions without a scale.
- Eat slowly and stop early. Stop as soon as you feel comfortably satisfied. NHS advice for nausea includes not eating too quickly and not lying down soon after eating.
- Keep a rhythm. The advisory suggests a small breakfast, then small meals every 3–4 hours, with enough fluids.
- Make each plate count. Combine a protein food, vegetables or fruit, and a whole grain or legume. The advisory favors minimally processed foods and suggests limiting refined carbohydrates, sugary drinks, red and processed meats and ultra-processed snacks.
How much protein do you need on GLP-1 medication?
When you lose weight quickly, part of what you lose is muscle. The joint advisory notes that rapid weight loss, with these medicines or other methods, often reduces both fat and muscle, and that low protein intake, little physical activity and older age make muscle and bone loss more likely.
The US recommended dietary allowance for adults is 0.8 g of protein per kilogram of body weight a day (about 0.36 g per pound). Higher targets, such as 1.2–1.6 g per kg (about 0.54–0.73 g per pound), have been proposed during active weight loss, but the advisory notes it is unclear which body weight to base them on. Ask a registered dietitian or your prescriber to set a target with you; our guide to how much protein you need per day explains the reference values.
Practical ways to get enough
- Eat protein first, as the advisory suggests, before you fill up.
- Choose compact sources such as fish, eggs, Greek yogurt, cottage cheese, nuts and seeds, beans, lentils or lean poultry.
- Go soft on queasy days. Soup, cottage cheese or a smoothie with fruit and unsweetened milk or yogurt is often easier than red meat or hard cheese.
Pair protein with strength training
According to the advisory, extra protein alone is unlikely to preserve muscle without structured strength training. It recommends strength training at least three times a week plus at least 150 minutes of moderate aerobic activity a week, adapted to your fitness level. If you are new to exercise, ask your doctor or a physiotherapist where to start.
What to eat when you feel sick
The NHS lists feeling or being sick, diarrhea and constipation among the common side effects of semaglutide and tirzepatide. Food can’t fix every symptom, but the NHS page on nausea and the joint advisory offer these ideas.
Things that may help
- Smaller, more frequent meals
- Regular sips of a cold drink
- Ginger or peppermint tea, or foods containing ginger
- Lighter foods such as soup, yogurt or cottage cheese
- Fresh air and a distraction
Things that often make it worse
- Hot, fried or greasy food, and strong-smelling food
- Eating quickly, or a large drink with your meal
- Large meals, and long gaps without food: the advisory describes a cycle where nausea stops people eating, which makes the nausea worse
- Alcohol
With diarrhea, avoiding large or high-fat meals can help, according to the advisory. If a side effect bothers you or does not go away, speak to a pharmacist or your prescriber.
Fiber and fluids for constipation and hydration
The advisory calls constipation common with weight loss and recommends enough fluids and fiber from food. Eating less usually means less fiber too, so choose fiber-rich foods on purpose.
- Increase fiber gradually, for example with prunes or other dried fruit, oats, whole grains, vegetables and legumes. 100 g (3.5 oz) of cooked lentils or chickpeas provides about 8 g of fiber, according to USDA FoodData Central.
- Go slower if nausea is the bigger problem. The advisory notes that avoiding fatty or high-fiber foods in the first few days can help.
- Sip through the day, and ask your pharmacist or prescriber if food and fluids aren’t enough.
Signs you need more fluid
The NHS lists thirst, headache, dark yellow or strong-smelling pee, peeing less often, dizziness, tiredness and a dry mouth as symptoms of dehydration. If you have been sick or have diarrhea, start with small sips, avoid caffeinated drinks and alcohol, and ask a pharmacist about oral rehydration solutions. The advisory notes that dehydration from severe nausea, vomiting or diarrhea can harm the kidneys.
Can you drink alcohol on GLP-1 medication?
The NHS says it is best not to drink alcohol while using semaglutide or tirzepatide, because it can increase feeling or being sick. The joint advisory adds that alcohol may worsen nausea and reflux and should be kept to a minimum. Alcohol also brings energy without protein or fiber and can add to dehydration. If you have diabetes or take other medicines, ask your prescriber what is safe for you.
How to avoid under-eating when you’re not hungry
Feeling less hungry is expected, but the advisory lists nutrient shortfalls from much lower intake among the main challenges of treatment, alongside muscle and bone loss.
- Set a reminder to eat if you often forget, as the advisory suggests.
- Don’t skip meals by default. People on these medicines can end up fasting without meaning to; the advisory encourages regular mealtimes even with intermittent fasting.
- Ask about supplements. The advisory says vitamin D, calcium, vitamin B12 or a multivitamin may be considered, tailored to each person; ask your prescriber or dietitian.
A sample day of small meals
An example to adapt, not a prescription: portions depend on your appetite, body and care plan.
| When | Small meal | Protein |
|---|---|---|
| Breakfast | 150 g (5 oz) plain Greek yogurt with berries and a spoonful of oats | 15 g |
| Mid-morning | 1 large hard-boiled egg (50 g) with cucumber or cherry tomatoes | 6 g |
| Lunch | Lentil soup or dal with 100 g (½ cup) cooked lentils and a little flatbread | 9 g |
| Afternoon | Miso soup with 100 g (3.5 oz) firm tofu, or 100 g (3.5 oz) cottage cheese with fruit | 17 g or 10 g |
| Dinner | 100 g (3.5 oz) baked cod, 80 g (½ cup) cooked rice and vegetables | 23 g |
| Evening, if hungry | 250 ml (1 cup) milk, or a small milk and fruit smoothie | 8 g |
With the tofu option, the main protein foods add up to about 78 g. Chicken, beans with tortillas or paneer can replace any of them.
When to get medical help
Based on NHS patient information, get urgent medical advice (in the UK, NHS 111) if you have:
- severe pain in your stomach or back that does not go away (a possible sign of an inflamed pancreas)
- severe tummy pain, which can be caused by gallstones or an inflamed gallbladder (listed for tirzepatide)
- signs of an allergic reaction, such as a swollen throat or tongue, a raised itchy rash or difficulty breathing
- signs of low blood sugar, such as sweating, shaking, a fast heartbeat or feeling dizzy, weak or confused, which is more likely if you also take other diabetes medicines
- signs of serious dehydration: dizziness on standing that does not go away, dark yellow pee or peeing less than normal, unusual tiredness, or a fast heartbeat or fast breathing
Call your local emergency number if dehydration comes with blue, gray, pale or blotchy skin, lips or tongue, cold skin, difficulty breathing, confusion, or unusual sleepiness. Your medicine’s leaflet lists all side effects.
How Portiva helps on GLP-1 medication
Portiva’s GLP-1 mode keeps your dose schedule and reminders as prescribed, gives you a symptom log to note nausea or constipation next to your meals, and shows a daily protein floor. It never suggests or changes a dose. You can log small meals by photo, voice or text, in bowls, cups and spoons as well as grams, and edit every portion before saving. Water you log is written to Apple Health.
Frequently asked questions
What should I eat on GLP-1 medication?
Build small meals around a protein food such as fish, eggs, Greek yogurt, cottage cheese, beans or lentils, add vegetables or fruit and a whole grain or legume, and drink fluids through the day. The 2025 joint advisory favors minimally processed, nutrient-dense foods. A registered dietitian can tailor this to you.
How much protein should I eat on semaglutide or tirzepatide?
There is no single number for everyone. The US recommended dietary allowance for adults is 0.8 g per kg of body weight a day, and higher targets such as 1.2–1.6 g per kg have been proposed during active weight loss. Ask a registered dietitian to set your target, and combine protein with strength training.
Is it OK to skip meals if I’m not hungry?
Try not to make it a habit. The joint advisory notes that long gaps without food can make nausea worse and leave you short of protein and other nutrients. Aim for small meals at regular times, keep easy options at hand and set a reminder if you tend to forget to eat.
Should I count calories while on GLP-1 medication?
It is optional. Logging for a while can show whether you get enough protein, fiber and fluid, and the joint advisory mentions food logs and food photos as useful tools for follow-up. If tracking makes you anxious, stop and talk to a professional. Our guide on how to count calories accurately covers the basics.
Sources
- Nutritional priorities to support GLP-1 therapy for obesity: a joint Advisory from the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association, and The Obesity Society, Obesity (2025).
- Semaglutide, NHS (2026).
- Tirzepatide, NHS (2026).
- Feeling sick (nausea), NHS (2023).
- Dehydration, NHS (2026).
- FoodData Central (SR Legacy), U.S. Department of Agriculture, Agricultural Research Service.