A low-FODMAP diet is a short-term elimination plan for people with irritable bowel syndrome (IBS): you cut back on certain fermentable carbohydrates for a few weeks, see whether symptoms settle, then bring foods back one at a time. The simplest way to do it is to learn a handful of swaps, pay attention to portion size (many foods are fine in small amounts), and keep a few 20-minute meals on repeat so you are never stuck.
What FODMAPs are, in plain terms
FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. These are carbohydrates that some people absorb poorly. They draw water into the gut and are fermented by gut bacteria, which can mean gas, bloating, cramping, diarrhea or constipation for people with a sensitive gut.
The U.S. National Institute of Diabetes and Digestive and Kidney Diseases lists foods high in FODMAPs as including some fruits (like apples and pears), dairy with lactose, legumes, some vegetables, wheat and rye, honey, and sweeteners ending in “-ol” such as sorbitol and xylitol. It also notes that your doctor may suggest trying the low-FODMAP diet for a few weeks and then slowly adding FODMAP foods back, because many people can tolerate some of them.
That second step matters. Low-FODMAP is not meant to be a forever diet. Its job is to help you find your personal triggers so you can eat as widely as possible.
The three phases
- Reduce (a few weeks): swap higher-FODMAP foods for lower-FODMAP versions and keep a simple symptom log.
- Reintroduce: if symptoms improve, test one FODMAP group at a time (for example, lactose, then fructans from wheat or onion) over a few days, noting how you feel.
- Personalize: keep eating everything you tolerate and limit only what clearly bothers you, in the amount that bothers you.
A registered dietitian who knows IBS can make this process faster and keep your diet from getting too narrow. The NHS advises seeing a GP if you need to avoid lots of different foods to control your IBS symptoms, since they can refer you to a dietitian or specialist.
Common swaps that make it simple
Most of the work is in a few everyday ingredients. Change these and you have covered a large share of a typical day.
| Instead of | Try |
|---|---|
| Garlic and onion | Garlic- or onion-infused oil, the green tops of green onions, chives, fresh herbs, ginger |
| Regular milk and yogurt | Lactose-free milk and yogurt, firm cheeses such as cheddar |
| Wheat pasta and bread | Rice, rice noodles, buckwheat noodles, quinoa, oats, sourdough spelt or gluten-free bread |
| Wheat flour tortillas | Corn tortillas |
| Honey | Maple syrup |
| Apples, pears, mango | Oranges, kiwi, strawberries, grapes, firm bananas |
| Cauliflower, mushrooms | Carrots, zucchini, bell peppers, baby spinach, bok choy, eggplant |
| Sugar-free gum and mints with “-ol” sweeteners | Regular versions in small amounts, or skip |
| Soy sauce in large amounts | Coconut aminos or a small splash of tamari |
Infused oils work because the fructans in garlic and onion do not dissolve into oil. Buy them ready-made, or warm sliced garlic in oil, then remove every piece before adding other ingredients.
Portions: the part most people miss
FODMAPs are about amount, not just the food. A small serving of avocado, sweet potato, almond butter or canned chickpeas may sit well, while a large one may not. Two practical habits help:
- Use a reference app. The Monash University FODMAP app lab-tests foods and shows serving sizes with a traffic-light rating. Serving sizes get updated, so check the app rather than relying on old lists.
- Watch “stacking.” Several small low-FODMAP servings of the same FODMAP type in one meal can add up. A meal with avocado, a big handful of cashews and a sweet sauce may be too much even if each item is fine alone.
Canned and well-rinsed lentils or chickpeas are often better tolerated than ones cooked from dry, which helps if you eat mostly plants. Firm tofu is another useful protein, since much of the FODMAP content drains away with the liquid.
20-minute meals to keep on repeat
Each of these uses the swaps above. Adjust portions using your app.
Crumbled tofu tacos
Crumble firm tofu into a pan with garlic-infused oil, cumin, smoked paprika and a pinch of salt. Cook until golden, about 10 minutes. Serve in warm corn tortillas with shredded lettuce, diced tomato, cheddar or lactose-free sour cream and green onion tops.
Ginger buckwheat noodle bowl
Boil buckwheat noodles. Meanwhile stir-fry carrot ribbons, bok choy and bell pepper in infused oil with fresh ginger. Toss everything with coconut aminos, a little maple syrup and rice vinegar. Top with sesame seeds and tofu or a fried egg.
Nourish bowl
Start with rice or quinoa (cook a big batch on the weekend). Add roasted or microwaved sweet potato in a modest portion, baby spinach, cucumber, a small scoop of rinsed canned chickpeas and a lemon-herb dressing made with olive oil, lemon juice, chives and salt.
Quick pasta salad
Cook gluten-free or rice pasta. Toss with cherry tomatoes, cucumber, olives, baby spinach, basil, cubes of cheddar or firm tofu and an olive oil and rice vinegar dressing. It keeps for lunches for two to three days in the fridge.
Simple squash and chickpea curry
Simmer cubed kabocha or butternut squash (keep butternut portions small) with canned coconut milk, curry powder, ginger, a handful of rinsed chickpeas and spinach. Serve over rice. Using pre-cut squash keeps it close to 20 minutes.
A sample low-FODMAP day
- Breakfast: oats made with lactose-free milk, topped with strawberries and a spoon of peanut butter.
- Lunch: leftover nourish bowl or pasta salad.
- Snack: an orange and a small handful of walnuts, or lactose-free yogurt.
- Dinner: tofu tacos or the buckwheat noodle bowl.
- Drinks: water, sparkling water, lactose-free milk, peppermint or ginger herbal tea.
Fibre still matters during this phase. Oats, quinoa, carrots, kiwi, strawberries and small servings of nuts and seeds help keep things moving. For more on getting fibre without discomfort, see our guide to fibre for digestion, and for other comfort strategies, our article on reducing bloating.
Eating out
- Choose simple dishes: grilled fish or tofu, rice, plain potatoes, steamed vegetables, salads.
- Ask for sauces and dressings on the side, since garlic and onion often hide there.
- Sushi with rice, cucumber and fish or tofu, or a rice-based Thai or Vietnamese dish without garlic, often works well.
- Do not stress over a single meal. The goal is a pattern, not perfection.
When to check with a professional
Get a medical assessment before starting if you have not been diagnosed with IBS, since other conditions can cause similar symptoms. See a doctor promptly for unexplained weight loss, blood in your stool, symptoms that wake you at night, a change in bowel habits after age 50, or a family history of bowel cancer or celiac disease. If you have a history of disordered eating, an elimination diet may not be right for you; talk to your healthcare provider, and you can reach NEDIC at nedic.ca for support.
Takeaways
- Low-FODMAP is a few-week test, followed by reintroduction, not a permanent diet.
- Most of the benefit comes from a few swaps: infused oils, lactose-free dairy, rice or buckwheat instead of wheat, and lower-FODMAP fruits and vegetables.
- Portion size matters as much as food choice; use a lab-tested app and watch stacking.
- Keep three or four 20-minute meals on rotation so you are never guessing at dinner.
- A dietitian can help you reintroduce foods and keep your diet varied.
FAQ
How long should the elimination phase last?
Usually a few weeks. If symptoms have not improved by then, talk with your doctor or dietitian rather than restricting further.
Do I have to give up garlic and onion flavour?
No. Infused oils, green onion tops and chives give much of the same flavour.