Fibermaxxing, the trend of deliberately maximising daily fibre intake, is the latest. Every few months, wellness TikTok discovers something the scientific community has known about for decades. The difference this time is that the researchers aren't rolling their eyes.
Fibre has, quietly and without the marketing fanfare of protein or omega-3s, accumulated one of the strongest evidence bases in nutrition. And yet most people are getting roughly half the recommended daily amount. So when the internet finally starts paying attention, the gut health community is here for it.
Here's what the science actually says, and where the trend gets a little more complicated.
Why fibre matters more than your childhood self was told
The old story about fibre was simple: it keeps you regular. True, but the story has grown considerably. Research now suggests that a fibre-rich diet may play a role in supporting immune function, cardiovascular health, blood sugar regulation, and potentially even mood and cognition, largely through its effects on the gut microbiome.
The mechanism centres on fermentation. When beneficial gut bacteria break down certain types of fibre, they produce short-chain fatty acids (SCFAs) such as butyrate and propionate. Early evidence suggests these compounds may be involved in a range of processes: supporting the gut lining, potentially modulating inflammation, and possibly influencing how the brain regulates stress and emotion. A 2025 study in Nature Metabolism found that these SCFA metabolites may act as epigenetic regulators, suggesting a link between what you eat and how your genes are expressed, though this area of research is still emerging.
The current UK and US dietary guidelines recommend 25 to 38 grams of fibre per day. The average person consumes somewhere around 15 to 20. That gap may matter more than we previously thought.
The 30 plants a week idea (and why diversity beats volume)
Fibermaxxing's smarter cousin is the 30 plants a week framework, which emerged from large microbiome research projects and has since become something of a shorthand for diverse, plant-forward eating. The principle is this: different plants feed different gut bacteria, so eating a wide variety of plant foods, including vegetables, fruit, grains, legumes, nuts, seeds, herbs, and spices, may support a more diverse and resilient gut microbiome.
Research from the American Gut Project found that participants who ate 30 or more different plants per week tended to have greater microbiome diversity than those eating 10 or fewer, along with higher levels of beneficial bacterial by products. The effect appeared to be driven by variety, not just volume.
This is where some experts have started to pump the brakes on raw fibermaxxing. Just chugging fibre supplements, while technically increasing your intake, may not replicate the benefit of genuinely varied plant consumption. As microbiome researchers have noted, the gut may thrive on diversity rather than repetition, which is a meaningful distinction when it comes to how you approach the trend.
We've written before about how sleep and the gut microbiome are connected in ways that might surprise you, in Is Your Gut Sabotaging Your Sleep? The fibre-mood axis runs through some similar pathways.
How to fibermaxx without the bloating
The most common side effect of dramatically increasing fibre intake is digestive discomfort: bloating, gas, and in some cases constipation. This tends to happen when people go from low intake to very high intake too quickly, without giving their gut bacteria time to adapt.
The approach that researchers and dietitians broadly support is gradual: add one or two new plant foods per week rather than overhauling your diet overnight. Drink plenty of water alongside fibre-rich foods. And focus on variety rather than hitting a specific gram target.
Some practical ways to build toward 30 plants without it feeling like a project:
Mixed spice blends count. A curry powder contains multiple plants. So does a herby salad dressing.
Frozen mixed veg are perfectly valid and may be nutritionally comparable to fresh in many cases.
Tinned pulses such as chickpeas, lentils, and black beans are fibre-dense and require zero prep.
Coffee and dark chocolate technically count. Yes, really.
A note for anyone with IBS or inflammatory bowel conditions: the relationship between fibre and symptoms is more complicated. Some types of fibre may aggravate rather than support gut health in certain individuals. Always worth speaking to a healthcare professional before making significant dietary changes.
Curious whether your diet changes are actually doing anything for your gut?
Gutsi tracks your digestive patterns passively over time, so you can start to see what's shifting. Join the waitlist at gutsi.com.
Wondering if what you're eating is making a difference?
Gutsi tracks your digestive patterns over time so you can see for yourself.
Discover Gutsi →
References
Sanz Y et al. The gut microbiome connects nutrition and human health. Nature Reviews Gastroenterology & Hepatology, 2025.
Nshanian M et al. Short-chain fatty acid metabolites propionate and butyrate are unique epigenetic regulatory elements. Nature Metabolism, 2025.
McDonald D et al. American Gut: An Open Platform for Citizen Science Microbiome Research. Cell Host & Microbe, 2018.
Hall CV et al. Characterising high-resolution dynamics of inflammatory and SCFA responses to food consumption. Cytokine, 2025.
This content is for informational purposes only and does not constitute medical advice. If you have concerns about your digestive health, please speak to a healthcare professional.
