Fibre-Maxxing Decoded: Is Eating More Fibre Really the Secret to Better Gut Health?

If you've done any scrolling on Instagram or TikTok recently, you've may have noticed the "fibre-maxxing" popping up. The trend is basically: eat as much fibre as possible by loading every meal with fruit, vegetables, legumes, wholegrains, nuts and seeds.

Unlike a lot of viral nutrition trends you may see, fibre-maxxing is actually based on something supported by decades of scientific research. Higher fibre intakes have consistently been associated with a lower risk of cardiovascular disease, type 2 diabetes, colorectal cancer and premature death, while also playing a fundamental role in maintaining a healthy gut microbiome (1,2).

However, there is one slight issue.

As a Nutritional Therapist specialising in digestive health, I often see people drastically increase their fibre intake over a short period, after hearing it's "good for your gut", only to experience more bloating, gas, abdominal pain and altered bowel habits. Obviously fibre is incredibly beneficial but the right type, the right amount and the right pace matter.

Let's look at what the science actually says.

What is fibre?

Fibre is the part of plant foods that resists digestion in the small intestine. Instead of being broken down and absorbed like carbohydrates, proteins or fats, fibre travels into the large intestine where it performs several important roles. Some fibres absorb water and support the softening of stools, others increase stool bulk, while many act as food for beneficial bacteria living within the gut microbiome (2). Fibre doesn't just help you "go to the toilet" it influences digestion, immunity, metabolism and even inflammation throughout the body.

Why fibre is essential for gut health

One of fibre's most important roles is feeding the trillions of bacteria that live in our digestive tract. These bacteria ferment certain fibres to produce compounds called short-chain fatty acids (SCFAs) including butyrate, acetate and propionate.

Research shows these compounds help:

• nourish the cells lining the colon

• maintain the integrity of the gut barrier

• regulate immune function

• reduce inflammation

• support healthy bowel movements

• influence metabolism and appetite regulation (2)

A diet high in fibre is associated with greater gut microbiome diversity. Although researchers are still learning exactly which bacteria are most beneficial, greater diversity is linked with better digestive and metabolic health (2).

Fibre does far more than support digestion

Although fibre has become synonymous with gut health, its benefits extend far beyond the digestive system.

Large systematic reviews involving hundreds of thousands of participants have found that higher fibre intakes are associated with:

• lower risk of cardiovascular disease

• reduced risk of stroke

• lower incidence of type 2 diabetes

• reduced risk of colorectal cancer

• improved cholesterol levels

• better blood glucose regulation

• lower all-cause mortality (1,3,4)

The landmark WHO-commissioned review published in The Lancet concluded that individuals consuming the highest amounts of dietary fibre experienced a 15–30% reduction in all-cause mortality and cardiovascular mortality in comparison with those consuming the least amount of fibre (1).

Not all fibre is the same

One of the biggest misconceptions online is that fibre is one single nutrient. In reality, there are many different types of fibre, each with different effects on digestion.

Soluble fibre

Soluble fibre dissolves in water to form a gel-like substance.

It can help:

• soften stools

• improve constipation

• lower LDL cholesterol

• support blood sugar control

• feed beneficial gut bacteria

Good food sources include:

• oats

• barley

• kiwi fruit

• apples

• pears

• citrus fruits

• chia seeds

• flaxseed

• beans

• lentils

• psyllium husk

Insoluble fibre

Insoluble fibre absorbs less water and adds bulk to stools.

It helps food move through the digestive tract and can reduce constipation for many people.

Sources include:

• wholegrain bread

• wheat bran

• brown rice

• nuts

• seeds

• vegetable skins

Most plant foods naturally contain a combination of both soluble and insoluble fibres (5).

Is fibre-maxxing always a good idea?

Not necessarily. Although increasing fibre intake is beneficial for most people, more is not always better, particularly if your digestive system is sensitive. Most people currently consume well below the UK recommendation of 30 g of fibre per day (6).

If someone eating only 12–15 g per day suddenly doubles or triples their intake, it's common to experience:

• bloating

• trapped wind

• abdominal discomfort

• increased bowel urgency

• loose stools

• constipation (in some people)

This doesn't necessarily mean fibre is causing harm. Instead, your gut microbiome needs time to adapt. Increasing fermentable fibres rapidly provides large amounts of fuel for gut bacteria, increasing gas production while the microbiome adjusts. For most people, fibre should be increased gradually over several weeks, alongside a good amount of fluid.

What if you have IBS?

This is where fibre advice becomes much more individual. Many people with Irritable Bowel Syndrome are told simply to "eat more fibre."

Unfortunately, this advice is often a little too simple. Clinical guidelines from the British Society of Gastroenterology recommend soluble fibre, particularly psyllium (ispaghula husk), as it has been shown to improve overall IBS symptoms (7). However, coarse insoluble fibres such as wheat bran may actually worsen bloating, abdominal pain and discomfort in some individuals with IBS (7,8). This is one reason why two people can eat exactly the same amount of fibre yet experience completely different symptoms.

It's not always about how much fibre you eat, it may be which fibres your gut currently tolerates.

Does eating more plants matter?

One aspect of the fibre-maxxing trend that should be really getting the attention is dietary diversity. Research suggests that consuming a larger variety of plant foods provides different fibres and phytochemicals that nourish different groups of gut bacteria (2).

Rather than fixating over reaching an extremely high fibre target very quickly, a better goal may be to gradually increase the variety of plants you eat across the week.

This could include:

• different vegetables

• seasonal fruit

• herbs

• spices

• wholegrains

• legumes

• nuts

• seeds

Every plant contributes slightly different nutrients and fibres that help support a healthier gut ecosystem.

Practical ways to increase fibre without upsetting your gut

If you currently struggle with bloating or digestive symptoms, avoid dramatically changing your diet overnight.

Instead:

• Add one extra portion of vegetables each day.

• Swap white bread or pasta for wholegrain versions if tolerated.

• Include oats for breakfast.

• Add a tablespoon of ground flaxseed or chia seeds gradually.

• Eat fruit with the skin on where appropriate.

• Include beans or lentils in small amounts if tolerated.

• Drink plenty of water as fibre intake increases.

Small, consistent changes are far more likely to improve symptoms than extreme dietary changes.

My advice as a Nutritional Therapist

Fibre is one of the most important nutrients for long-term health, but gut health is rarely as simple as "eat more fibre." If increasing fibre consistently leaves you feeling worse, it may indicate an underlying issue such as IBS, food intolerances, gut dysbiosis, constipation, coeliac disease or another digestive condition that deserves further investigation.

Rather than following social media trends, it's important to understand which foods work for your gut and why. A personalised approach often leads to better symptom control than simply chasing the highest fibre intake possible.

The bottom line

The fibre-maxxing trend highlights something that nutrition science has known for decades: most people would benefit from eating more fibre.

However, fibre isn't a competition. For better digestive health, focus on gradually increasing your intake from a wide variety of whole plant foods, paying attention to how your own digestive system responds.

If you have persistent bloating, abdominal pain, constipation, diarrhoea or IBS symptoms, don't assume that simply eating more fibre is the answer.

References

1. Reynolds A, Mann J, Cummings JH, Winter N, Mete E, Te Morenga L. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Lancet. 2019;393(10170):434–445.

2. Makki K, Deehan EC, Walter J, Bäckhed F. The impact of dietary fibre on gut microbiota in host health and disease. Cell Host & Microbe. 2018;23(6):705–715.

3. Veronese N, Solmi M, Caruso MG, et al. Dietary fibre and health outcomes: an umbrella review of systematic reviews and meta-analyses. American Journal of Clinical Nutrition. 2018;107(3):436–444.

4. Aune D, Chan DSM, Lau R, et al. Dietary fibre, whole grains and risk of colorectal cancer: systematic review and dose-response meta-analysis of prospective studies. BMJ. 2011;343.

5. Slavin JL. Fibre and prebiotics: mechanisms and health benefits. Nutrients. 2013;5(4):1417–1435.

6. Scientific Advisory Committee on Nutrition (SACN). Carbohydrates and Health. London: The Stationery Office; 2015.

7. Vasant DH, Paine PA, Black CJ, et al. British Society of Gastroenterology Guidelines on the Management of Irritable Bowel Syndrome. Gut. 2021;70(7):1214–1240.

8. Moayyedi P, Quigley EMM, Lacy BE, et al. The effect of fibre supplementation on irritable bowel syndrome: a systematic review and meta-analysis. American Journal of Gastroenterology. 2014;109:1367–1374.