How do you plan a low FODMAP diet for a client?
In short: A low FODMAP diet is a short, three-phase process for people with irritable bowel syndrome (IBS). It has a restriction phase of a few weeks, structured reintroduction of FODMAP groups, and a personalised long-term diet that limits only the FODMAPs and amounts that trigger symptoms.
It isn't meant to be followed strictly for life. Before starting, make sure IBS has been appropriately diagnosed and coeliac disease has been excluded, and ideally involve a dietitian or healthcare professional experienced in the low FODMAP diet.
1 min 11 s videoCaptions onUpdated 5 October 2026
Who it suits, and who needs a different plan
The diet is for adults with a diagnosis of IBS whose symptoms haven't settled with first-line advice such as regular meals, less alcohol and caffeine, and adjusting fibre. The American College of Gastroenterology recommends a limited trial of it for IBS, and NICE in the UK says exclusion diets like this should only be given by a healthcare professional with expertise in dietary management.
Before you start, check that coeliac disease has been ruled out with a blood test while the client was still eating gluten. Going low FODMAP first cuts wheat, which can make that test unreliable later.
- Refer for medical assessment if there are red flags such as unexplained weight loss, rectal bleeding, iron-deficiency anaemia, a persistent unexplained change in bowel habit or other symptoms that raise concern for an alternative diagnosis. These should be investigated rather than assumed to be IBS.
- Think twice for clients with a history of disordered eating, clients who are underweight, children, and anyone already on a restricted diet such as vegan. The diet can still work, but it needs closer supervision.
The FODMAP groups and where they hide
FODMAPs are short-chain carbohydrates that are poorly absorbed in the small intestine. They draw water into the gut and are fermented by bacteria in the large bowel, which is where the bloating, pain and change in bowel habit come from.
| Group | Common high sources | Lower FODMAP options |
|---|---|---|
| Fructans | Wheat, rye, onion, garlic, inulin or chicory root in "high fibre" products | Oats, rice, potato, garlic-infused oil, green tops of spring onions |
| GOS (galacto-oligosaccharides) | Chickpeas, lentils, kidney and baked beans | Firm tofu, tempeh, small portions of tinned and rinsed lentils |
| Lactose | Milk, yoghurt, ice cream, soft cheeses | Lactose-free milk and yoghurt, hard cheeses |
| Excess fructose | Apple, pear, mango, honey, fruit juice | Orange, kiwifruit, strawberries, grapes |
| Polyols (sorbitol, mannitol) | Stone fruit, mushrooms, cauliflower, sugar-free gum and mints | Carrot, cucumber, lettuce, green beans |
Portion size matters. Many foods are low FODMAP at one serving size but become moderate or high FODMAP at larger amounts. Use current, laboratory-tested serving-size information, such as the Monash FODMAP app, rather than relying on simple lists of 'allowed' and 'avoid' foods.
Planning the restriction weeks
The initial low FODMAP phase is generally followed for 2–6 weeks. If symptoms improve, move on to structured reintroduction rather than continuing strict restriction. If symptoms have not improved, review adherence, the diagnosis and other potential management strategies rather than simply extending the restrictive phase.
- Keep fibre up. Cutting wheat and legumes can drop fibre fast. Build in oats, brown rice, quinoa, potatoes with skins, chia or linseed, and kiwifruit.
- Protect calcium. If dairy goes, use lactose-free dairy or a calcium-fortified plant milk that is tested low FODMAP.
- Plan swaps, not gaps. Onion and garlic flavour most savoury food. Garlic-infused oil, chives, ginger and spring onion tops keep meals edible.
- Teach label reading. Onion and garlic powder, inulin, chicory root, honey and sweeteners ending in -itol turn up in stock cubes, sauces and "gut friendly" snacks.
Restriction also lowers bifidobacteria in the gut in several trials, which is another reason not to leave a client in phase one.
Reintroduction and personalisation
Once symptoms have improved, begin structured reintroduction while keeping the background diet low FODMAP. The aim is to identify which FODMAPs trigger symptoms and the amounts the client can tolerate. A practical approach is:
- Challenge one FODMAP at a time using a food that provides a meaningful amount of the FODMAP being tested, while keeping the rest of the diet relatively stable.
- Increase the amount of the challenge food progressively over several days while recording gastrointestinal symptoms and bowel habit. Stop the challenge if symptoms become significant.
- Allow symptoms to return to baseline before beginning the next challenge.
- Work systematically through the relevant FODMAP groups. Record the food, amount and symptom response so that the long-term diet can be personalised around the client's individual tolerance.
Personalisation brings back the foods and FODMAPs the client tolerates and limits only those that consistently trigger symptoms, at the amounts that cause problems. Tolerance can change over time, so previously poorly tolerated foods can be re-challenged where appropriate. The goal is the least restrictive diet that provides acceptable symptom control.
How to do it in Foodzilla
Foodzilla has forms to record symptoms before and during the diet, a Low FODMAP label for the meal plan generator, and a ready-made Low FODMAP plan to start from. The label marks a recipe as low FODMAP as a whole. It does not check each portion against tested serving sizes, so that check is yours.
- 1Go to Forms & Bookings and stay on the Forms tab. Under Templates, press Use template on Gut Health / Digestive Symptom Assessment for the first appointment and on Food & Symptom Diary (7-Day) for a baseline week, then press Save Form on each copy.
- 2Send them from the client's dashboard with More, then Forms..., then Send Form. When the diary comes back, press View Submission. Analyse nutrition gives a rough nutrient estimate, and Push to diary copies the meals into the client's food diary.
- 3Open the client's Health & Diet Goals and go to the Diet Preferences tab (Professional plan and above). Tick Low FODMAP under Health & Allergies, and add any single foods the client already knows they react to under Foods to Avoid.
- 4Go to Meal Plans, choose the client and press Auto-Generate. Low FODMAP is already selected under Dietary needs & ingredients. Press Generate plan. To start from a finished week instead, choose New Plan, then Import From Template, and pick Low FODMAP Plan 2000 kcal from the Templates Database.
- 5Before you send the plan, read every recipe and check the portion of any ingredient that is only low FODMAP in small amounts. Replace a recipe that goes over with Manual Swap from its menu.
Good to know
- Get the baseline before anything changesAsk the client to record their usual food intake and symptoms before starting the restriction phase, then repeat the same monitoring towards the end. Comparing symptoms before and during the intervention helps assess whether the diet has produced a meaningful improvement.
- Put the end date on the planWrite the date the restriction phase finishes in the plan notes. Clients who feel better may be reluctant to reintroduce foods, so setting an end point from the start helps prevent the restriction phase continuing unnecessarily.