Fibremaxxing and IBS: Can Too Much Fibre Backfire?

Written By Aimee Newton

Fibremaxxing, deliberately piling extra fibre onto every meal, is one of the biggest nutrition stories of 2026. TikTok is full of chia puddings, bean bowls, bran sprinkles and prebiotic shots. But if you live with IBS or regular bloating, suddenly doubling your fibre isn't automatically a good idea, and for some people it makes bloating worse rather than better. For some people, adding more fibre is like adding more traffic to a jam and hoping it clears quicker. It won't. It'll make it worse.

Why Fibremaxxing Has Taken Off in 2026

Fibre feeds the bacteria in your gut, helps keep bowel movements regular, and is linked to long-term health benefits, which is exactly why it has become such a popular focus. The NHS recommends adults aim for 30g of fibre a day, yet the average UK adult eats closer to 20g. I've seen people getting as little as 10g a day, nowhere near half the target. That gap is real, and closing it matters. The problem with fibremaxxing as a trend is the "more, faster" approach it encourages, which isn't how a sensitive gut wants to be treated.

Fibre Isn't Just "Soluble" or "Insoluble"

Most fibre advice stops at soluble versus insoluble, but that split doesn't actually predict how your gut will react. Research published in the Journal of the Academy of Nutrition and Dietetics has shown that solubility alone does not predict a fibre's physiological effect, and a review in Nature Reviews Gastroenterology & Hepatology reaches the same conclusion. What matters more is a combination of properties:

  • Particle size (roughage): coarse, intact particles, such as wheat bran, mechanically stimulate the colon and speed up transit.

  • Viscosity: how much a fibre thickens and gels with water, as psyllium, oats and ground flaxseed do. This softens stool and improves consistency.

  • Fermentability: how readily gut bacteria break a fibre down. Fermentation produces gas as a normal by-product, and highly fermentable fibres, such as inulin and other prebiotics, are the ones most likely to cause bloating.

The upshot: a fibre being "soluble" tells you almost nothing about whether it will bloat you. Ispaghula (psyllium) and inulin are both soluble, but psyllium is low in fermentability and gentle, while inulin ferments rapidly and is a common bloating trigger.

IBS-C and IBS-D Need Different Approaches

Not everyone with IBS has the same symptoms, and that changes what "more fibre" should actually mean.

  • If your IBS is constipation-predominant (IBS-C), the NHS recommends soluble fibre such as oats, linseeds, carrots and peeled potatoes. If gas and bloating are also a problem, the aim is to increase viscosity while keeping fermentability low, which is exactly why psyllium tends to be well tolerated where bran isn't.

  • If your IBS is diarrhoea-predominant (IBS-D) or transit is already fast, the NHS advises cutting back on high-fibre wholegrain foods, nuts and seeds, and reducing particle size (roughage) tends to help rather than reducing fibre altogether.

  • If gas and bloating are the main complaint, the evidence points to cutting back on rapidly fermentable fibres first.

This lines up with UK clinical guidance. NICE's guideline on IBS specifically advises that "people with IBS should be discouraged from eating insoluble fibre (for example, bran)", and that where more fibre is needed, "it should be soluble fibre such as ispaghula powder or foods high in soluble fibre (for example, oats)." A 2022 UK consensus paper on diet and IBS, published in BMC Medicine, reached a similar conclusion: the trial evidence for benefit sits with soluble fibre such as ispaghula, not insoluble fibre like wheat bran.

Focus on Texture, Not Grams

If fibremaxxing has left you more uncomfortable rather than less, the fix generally isn't to abandon fibre. It's to change its texture before you change the amount. You can keep most of the fibre in a food while making it far gentler on a reactive gut, simply by changing its particle size:

  • Fruit salad becomes a smoothie.

  • A whole apple becomes stewed apple or apple sauce.

  • A raw vegetable salad becomes soup, or well-cooked, soft vegetables.

  • Whole nuts become a smooth nut butter.

Alongside that, go slowly. Guts UK, the digestive health charity, is direct on this point: "it is important to increase fibre intake slowly and drink plenty of water", whatever type of fibre you're adding. 

In practice, that means:

  1. Add one new fibre source at a time, not five at once.

  2. Favour viscous, gently fermenting fibres first (oats, psyllium, ground flaxseed) if bloating is your main issue.

  3. Modify texture (blend, cook, mash) before you cut a food out altogether.

  4. Increase your water intake alongside your fibre, not after the fact.

  5. Give each change one to two weeks before adding the next.

Overall…. 

Fibremaxxing isn't wrong. Most of us in the UK are genuinely under-eating fibre against the NHS's 30g-a-day target. But for anyone with IBS or regular bloating, how you add fibre back in, and in what form, matters as much as how much you add. Go slowly, choose fibres with the right viscosity and fermentability for your symptoms, and keep the water topped up.

If fibremaxxing has left you more bloated rather than less,  

Sources

Aimee Newton
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