loamWhat FODMAPs are
FODMAPs are fermentable carbs — Fermentable Oligo-, Di-, Mono-saccharides And Polyols — that draw water into the gut and ferment quickly. In people with IBS, that combination can trigger gas, bloating and cramping. The low-FODMAP diet is a structured, temporary tool for identifying which of these carbs are personal triggers, usually run in three phases: elimination (2–6 weeks), reintroduction, and personalisation. It's best done with a dietitian, since the elimination phase is meant to be short and diagnostic — not a long-term way of eating.
Why fiber and FODMAPs collide
The trouble is that several fiber all-stars are also high-FODMAP:
- Beans and lentils — high in GOS (galacto-oligosaccharides)
- Wheat and rye — high in fructans
- Onion and garlic — high in fructans
- Apples and pears — excess fructose and sorbitol
Cutting these during elimination can accidentally cut your fiber intake along with them, so the goal isn't to eat less fiber — it's to swap deliberately toward low-FODMAP sources that still deliver it.
Low-FODMAP, high-fiber foods
Plenty of foods thread the needle: real fiber, low FODMAP load in a typical serving.
| Food | Fiber /100 g | Notes |
|---|---|---|
| Chia seeds | 34 g | Soak first; 1–2 tbsp serving |
| Flaxseed | 27 g | Ground; ~1 tbsp |
| Oats | 10 g | Rolled; ½ cup serving |
| Quinoa | 2.8 g | Cooked; naturally low-FODMAP grain |
| Firm/under-ripe banana | 2.6 g | Ripens toward higher FODMAP — eat firm |
| Kiwi | 3 g | Low-FODMAP fruit staple |
| Orange | 2.4 g | Whole fruit, not juice |
| Raspberries | 6.5 g | Small serving |
| Carrots | 2.8 g | Raw or cooked |
| Spinach | 2.2 g | Low-FODMAP leafy green |
| Potato with skin | 2 g | Keep the skin on |
| Walnuts & peanuts | ~7 g | Small handful |
| Canned lentils | 4–5 g | Rinsed, small portion |
Note that portion size is doing a lot of the work here — many of these foods are low-FODMAP at a modest serving but tip into moderate or high territory at a larger one.
Favour soluble fiber during the strict phase. Oats, chia, flax, carrots and oranges lean soluble, which tends to be gentler on a sensitive gut — and pair them with water. Portion matters more than the food itself: a small serving of a food can be low-FODMAP while a large one tips to high.
A note on doing this safely
The low-FODMAP diet isn't meant to be permanent. The goal of elimination is always to move on to reintroduction and personalisation — figuring out your specific triggers and thresholds, then widening your diet back out around them. Because eliminating whole food groups can affect both fiber intake and overall nutrition, it's best done with a registered dietitian. loam supports general wellness and education and is not a substitute for medical advice.
Low / moderate / high FODMAP labels, built in
loam tags catalog foods with low / moderate / high FODMAP labels, based on published Monash-style cutoffs, so you can raise fiber while staying mindful of FODMAPs — and still see your soluble, insoluble and prebiotic split each day. Free, no account, private by design.
Download loam on the App Store →Frequently asked
Can you eat fiber on a low-FODMAP diet?
Yes — choose low-FODMAP fiber sources like oats, chia, flax, quinoa, carrots and firm bananas instead of high-FODMAP staples like beans, wheat, onion and garlic.
What are the best low-FODMAP high-fiber foods?
Chia and flaxseed, oats, quinoa, firm banana, kiwi, oranges, carrots, and small servings of nuts are among the best low-FODMAP, high-fiber choices.
Is oatmeal low-FODMAP?
Yes, in typical servings — around ½ cup of rolled oats — and it's rich in soluble fiber, making it a gentle option during a low-FODMAP approach.
Sources: low-FODMAP framework (Monash University); FODMAP thresholds per Varney et al. 2017; work with a dietitian. loam supports general wellness and education — it is not medical advice.