The complete IBS diet guide. What to eat, what to limit and how to find your triggers

For years, food felt like my enemy. I had diarrhoea-type IBS, and every meal felt like a gamble. I skipped dinners out, carried medicine everywhere and blamed a new food every week.

What finally helped was not a magic list of banned foods. It was a clear, step by step IBS diet, followed by the slow work of finding my own triggers. Today I eat freely again, and I help clients in more than 15 countries do the same.

This guide brings together what the best research shows about eating with IBS. You will learn what to eat every day and how the low FODMAP diet really works. You will also learn how to find your personal triggers and protect your gut bacteria.

What is the best IBS diet?

There is no single best IBS diet for everyone, but there is a best order to try things. Start with simple daily habits. If they are not enough, a low FODMAP diet has the strongest research. Then you bring foods back to find what your own gut can handle.

IBS is common. In a global survey of 73,076 adults, about 4 in 100 online respondents met the strict Rome IV criteria for IBS. Many more live with milder gut symptoms.

The American College of Gastroenterology and the British Society of Gastroenterology both support diet as a core treatment. Both suggest a limited trial of a low FODMAP diet, ideally with a dietitian, and soluble fibre rather than bran.

Is it really IBS? Check these signs first

Before you change your diet, make sure a doctor has diagnosed IBS. Some symptoms point to other conditions that need tests.

Please see a doctor soon if you notice any of these.

• Blood in your stool, or black, tarry stools
• Weight loss you cannot explain, even a few kilograms (several pounds)
• Diarrhoea that wakes you up at night
• Fever, ongoing vomiting or trouble swallowing
• New symptoms after age 50
• A family history of bowel cancer, coeliac disease or inflammatory bowel disease

A doctor may also test for coeliac disease before you cut out wheat. Cutting out gluten first can make that test less accurate.

What should I eat every day with IBS?

Begin with the basics, because they help many people and cost nothing. The UK’s National Institute for Health and Care Excellence, known as NICE, gives this first-line advice.

• Eat regular meals and take your time. Do not skip meals or leave long gaps.
• Drink plenty of fluids, mostly water or caffeine-free drinks.
• Keep tea and coffee to about 3 cups a day.
• Cut back on alcohol and fizzy drinks.
• Limit fresh fruit to 3 portions a day. One portion is about 80 g, roughly 3 ounces.
• Avoid sorbitol, a sweetener in sugar-free gum, mints and drinks, if you have diarrhoea.
• Try oats and linseeds for wind and bloating, up to 1 tablespoon of linseeds a day.

Many dietitians call this “traditional dietary advice”. It also usually means smaller meals and less fatty, greasy food.

Try this. For two weeks, eat three meals and one or two small snacks at roughly the same times each day. Notice if your gut settles when it knows what to expect.

Does simple advice work as well as the low FODMAP diet?

For many people, yes, and this surprises most readers. Three trials compared simple habits with the low FODMAP diet.

In a 2015 Swedish trial of 75 people, about half improved on each diet after four weeks. There was no real difference between them. In a 2022 UK trial of 99 people with non-constipated IBS, 42% improved with simple advice, 55% with low FODMAP and 58% with gluten-free eating. Again, the difference was too small to be sure.

The simple advice was cheaper, quicker to shop for and easier when eating out. That is why some experts now suggest starting with it. I agree. A gentler start also lowers the risk of food fear, which I explain below.

How does the low FODMAP diet work?

FODMAPs are short-chain carbohydrates that your small intestine absorbs poorly. They pull water into the gut, and bacteria in the colon ferment them. In people with a sensitive gut, that extra water and gas can bring pain, bloating, wind and changes in stool.

The name stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. In plain words, that means fructans and galacto-oligosaccharides, lactose, excess fructose and sugar alcohols.

The evidence is strong. In a 2014 Monash University trial, 30 people with IBS ate a low FODMAP diet and a typical diet for three weeks each. Their overall symptom scores were about half as high on the low FODMAP diet.

A 2022 review pulled together 13 trials with 944 people. The low FODMAP diet ranked first of all the diets tested for overall symptoms, belly pain and bloating.

Newer trials show diet can beat medicine. In a 2024 Swedish trial of 294 adults, 76% improved on a low FODMAP diet combined with simple advice, compared with 58% on standard medicine. A Belgian trial of 459 people in family practices found similar results. After eight weeks, 71% improved with a FODMAP-lowering app, compared with 61% on a gut-relaxing medicine.

An honest limit. Most trials last only four to eight weeks, and people often know which diet they are on. That makes the placebo effect hard to rule out completely.

Which foods are high and low in FODMAPs?

Monash University tests foods in its lab and keeps the most trusted list. Portion size matters a lot, so a small serving of some foods is fine. Here is a simple starting guide.

Common high FODMAP foods to swap during the first phase

• Vegetables, onion, garlic, leek bulb, asparagus, cauliflower and mushrooms
• Fruit, apples, pears, mango, watermelon, cherries and dried fruit
• Grains, large servings of wheat, rye and barley bread, pasta and cereal
• Legumes, large servings of beans, chickpeas and lentils
• Dairy, regular milk, soft cheese and yogurt if lactose bothers you
• Sweeteners, honey, agave, high fructose corn syrup, sorbitol and mannitol

Low FODMAP swaps that still taste good

• Vegetables, carrots, zucchini, cucumber, spinach, potatoes, tomatoes, eggplant and the green tops of spring onions
• Fruit, firm bananas, kiwifruit, oranges, grapes, pineapple and strawberries
• Grains, rice, oats, quinoa, millet, polenta and real sourdough spelt bread
• Protein, eggs, fish, chicken, firm tofu and tempeh
• Dairy, lactose-free milk and yogurt, and hard cheeses like cheddar
• Flavour, garlic-infused oil, chives, ginger, cumin, herbs and lemon

Garlic is one of the trickiest foods, because it hides in so many sauces and spice mixes. I wrote a full guide on whether garlic is low FODMAP and what to use instead.

Want to test yourself? Play Trigger or Safe and see how many foods you can sort correctly in one minute.

How long should I follow a low FODMAP diet?

Only for a short time. The low FODMAP diet has three steps, and the strict first step is meant to last about 2 to 6 weeks.

1. Swap. Replace high FODMAP foods with low FODMAP choices for 2 to 6 weeks.
2. Reintroduce. Test one FODMAP group at a time over a few days, while keeping the rest of your diet low FODMAP.
3. Personalise. Bring back every food that suits you, and limit only the ones that cause trouble.

If your symptoms have not improved at all after 4 to 6 weeks, the diet may not be right for you. Please stop and talk to your doctor or dietitian, rather than cutting even more foods.

How do I find my personal IBS triggers?

Your triggers are personal, and the reintroduction step is how you find them. It is the most important part of the diet and the step most people skip.

A 2024 Belgian trial tested this carefully with 117 people. Those who improved on the diet then took hidden powders of each FODMAP, one at a time. On average, each person reacted to 2 or 3 FODMAP groups, not all of them.

Fructans triggered symptoms in 56% of people and mannitol in 54%. Galacto-oligosaccharides, found in beans and lentils, came next at 35%. Lactose, fructose and sorbitol each affected fewer than 3 in 10.

Here is the twist. Plain glucose, used as a dummy powder, also brought symptoms back in 26% of people. Expecting a reaction can create one, so a calm, slow approach matters.

Bringing foods back works over time too. In a UK study of 103 people, 12% had good symptom relief at the start. That rose to 61% after the strict phase and stayed at 57% after reintroduction. Their diets were still nutritionally adequate.

Try this. Pick one test food, such as half a slice of wheat bread for fructans. Eat a small amount on day 1, a medium amount on day 2 and a normal amount on day 3. Note your symptoms. Then rest for 2 or 3 days before testing the next group.

What does a strict IBS diet do to your gut bacteria?

I strongly believe gut health plays a major role in nearly every health condition. So I never treat the low FODMAP diet as a forever plan, because many FODMAPs feed your helpful gut bacteria.

In a 2015 Monash trial, 27 people with IBS and 6 healthy people ate each diet for 21 days. The low FODMAP diet lowered the total number of gut bacteria. The typical diet raised butyrate makers and Akkermansia, a bacteria that lives in the protective mucus layer of the gut.

A 2021 UK analysis of 95 people looked at Bifidobacterium, a friendly bacteria. On the low FODMAP diet it made up 0.9% of the gut community, compared with 2.1% on a sham diet. Interestingly, a probiotic taken at the same time softened this drop.

The Monash team notes that this short-term drop has no known harm so far. Long-term effects are still unclear. That is exactly why I bring foods back as soon as a client feels steady.

Try this. Feed your gut with low FODMAP plants while you follow the diet. Oats, kiwifruit, carrots, spinach, quinoa, firm tofu and small portions of canned lentils are all good options. The Gut Garden game makes it fun to count your plants each week.

Which fibre is best for IBS?

Soluble fibre is usually best. It forms a soft gel, which helps both loose and hard stools. Insoluble fibre like bran is rougher and can make symptoms worse for some people.

In a 2009 trial in the BMJ, 275 people with IBS took psyllium, bran or a dummy powder for three months. In the first month, 57% improved on psyllium compared with 35% on the dummy powder. People quit bran most often because their symptoms got worse.

For constipation, kiwifruit is a tasty option. In an international trial, people with IBS-C ate 2 green kiwifruits a day for four weeks. They had almost 2 more complete bowel movements each week. Their gut comfort improved too.

Try this. Start with half a teaspoon of psyllium husk in a full glass of water once a day. Increase slowly over two to three weeks. Always drink plenty of water with it.

Does the IBS diet differ for diarrhoea and constipation?

The core steps are the same, but the details change. Your main symptom guides the small adjustments.

• IBS with diarrhoea. Avoid sorbitol and other sugar alcohols. Go easy on coffee, alcohol, greasy meals and very large portions. Psyllium can help firm stools.
• IBS with constipation. Drink plenty of water, add green kiwifruit, oats or linseeds, and increase soluble fibre slowly. Gentle daily walks help too.
• Mixed IBS. Regular meal times and soluble fibre help steady things. A diary shows which pattern you are in each week.

During a bad day, small and simple meals are kinder to your gut. My guide on how to calm an IBS flare-up shows exactly what to eat for the next few days.

Can food fear make IBS worse?

Yes, and this is the part of IBS care I care about most. When food hurts, it is natural to avoid more and more of it. Over time, that can shrink your diet and your life.

A 2026 French study of 326 people with IBS at a specialist centre found that 47.5% had signs of restrictive eating. About a third met the criteria for a restrictive eating disorder. These people had worse gut symptoms and more low mood.

Please do not cut foods without a plan, and never stay strict longer than you need to. If you feel scared of eating or are losing weight, ask your doctor or dietitian for help.

Stress and your gut also talk all day. My guide to calming stress and the free 30-Day Calm Gut Challenge can help you build a calmer daily routine.

How I use the IBS diet with my clients

My own IBS recovery taught me that diet works best inside a bigger plan. With clients, I follow three phases.

1. Identify, week 1. We look for the root cause. I ask about your sleep, stress, cycle, medicines and your poop, and we start a food and symptom diary.
2. Stabilise, weeks 2 to 8. We calm the gut with regular meals, soluble fibre and a gentle low FODMAP phase if needed.
3. Sustain, months 3 to 4. We bring foods back, one group at a time, until your diet is as wide and joyful as possible.

I also borrow from global traditional Ayurveda. A sattvic way of eating favours fresh, simple, home-cooked meals and skips onion and garlic. Monash lists onion and garlic among the richest sources of fructans, the most common trigger in the Belgian trial. Old wisdom and new science often meet in the kitchen.

A sample low FODMAP day

• Breakfast. Oats cooked in lactose-free milk, topped with sliced kiwifruit and a spoon of ground linseed
• Snack. A firm banana and a small handful of walnuts
• Lunch. Rice bowl with grilled chicken or firm tofu, cucumber, carrot, spinach and a lemon and olive oil dressing
• Snack. Lactose-free yogurt with strawberries
• Dinner. Baked fish or tempeh, roast potatoes, zucchini cooked in garlic-infused oil and a sprinkle of chives

This is a sample, not a prescription. Your portions depend on your size, activity and goals.

Frequently asked questions

What foods should I avoid with IBS?

There is no single list for everyone. Common triggers include onion, garlic, wheat in large portions, beans, apples, pears, regular milk, sugar-free sweets, alcohol, coffee and greasy food. A low FODMAP trial followed by careful reintroduction shows which of these affect you.

Is the low FODMAP diet a forever diet?

No. The strict phase should last about 2 to 6 weeks. After that, you bring foods back one group at a time and keep only the limits you truly need. Staying strict for too long can reduce helpful gut bacteria and make eating stressful.

Can I follow an IBS diet without a dietitian?

Many people start with simple habits on their own, such as regular meals and less coffee and alcohol. For the low FODMAP diet, guidelines recommend support from a trained dietitian, because it is easy to cut too much and get the reintroduction wrong.

How fast does an IBS diet work?

In trials, many people felt better within four weeks, and some within one or two. No change at all after 4 to 6 weeks on a low FODMAP diet? Then talk to your doctor or dietitian about other options.

Is gluten-free eating good for IBS?

Some people feel better without wheat, but often fructans in wheat are the real trigger, not gluten. A 2022 trial found gluten-free eating worked about as well as low FODMAP and simple advice. Check for coeliac disease with your doctor before you cut out gluten.

What I want you to remember

The best IBS diet is the widest diet your gut can handle. Start with simple daily habits. Use the low FODMAP diet as a short test, not a life sentence. Then bring foods back and protect your gut bacteria with as many plants as you tolerate.

Food was once my enemy too. Now it is one of my favourite parts of the day. With patience and the right steps, it can be yours again.

Not sure where to start? Take the 2 minute Gut Check quiz for a personal plan, then explore my other IBS guides.