You scroll through videos on your phone and see someone eating oatmeal with chia seeds and raspberries for breakfast, lentil soup for lunch and bean stew for dinner. In the corner of the screen, the grams of fibre in each meal are added up, and by the end of the day, the number is impressive. The thought quickly occurs to you: if fibre is so good for you, why not try it yourself?
A couple of days later, you’re sitting at work feeling like a balloon.
On social media, increasing your fibre intake is called “fibermaxxing”. The idea itself makes sense, but a sudden increase in intake can cause gas and bloating. If fluid intake is insufficient, some people may also experience constipation (Cohen, 2026).
This time, I looked for answers to three questions: how much fibre do we really need, what does research say about digestive discomfort, and do all fibre supplements work the same way?
What is “fibermaxxing”?
“Fibermaxxing” is a term popular on social media that means deliberately increasing fiber intake. In practice, this often means more legumes, berries, whole grains, vegetables, and seeds.
The trend is not fundamentally a new discovery. It draws attention to a real problem: people often consume less fiber than recommended. However, UCLA Health nutrition specialist Yasi Ansari recommends making fiber-rich foods a daily habit rather than maximizing intake. While no definitive safe upper limit has been established (Cohen, 2026), that does not mean the highest intake is the best.
Some content creators, however, recommend eating 80 grams of fiber a day or even more. In an NPR article, UCLA Health gastroenterologist Berkeley Limketkai warned that someone who is not used to that amount could experience various side effects if they suddenly increase their intake to 70–90 grams a day. He also noted that in some cultures with traditionally plant-based diets, such a high intake is not at all unusual (Godoy, 2026).
How much fibre is enough?
According to the Nordic and Baltic nutrition recommendations (NNR 2023), adults should consume at least 3 grams of fibre per megajoule of dietary energy. At the reference energy intake, this amounts to at least 25 grams a day for women and 35 grams for men (Nordic Council of Ministers, 2023). Nutrition surveys in the region have found average intakes of 16–22 grams for women and 18–26 grams for men, so intake generally falls below the recommendation (Carlsen & Pajari, 2023).
Examples of foods that help add fibre to your diet include:
Wholegrain foods: rolled oats, wholegrain rye bread and pearl barley.
Legumes: beans, lentils, chickpeas and peas.
Fruit, berries and vegetables: raspberries, pears, apples and broccoli.
Nuts and seeds: almonds, flaxseeds and chia seeds.
The grams become easier to grasp when you look at an ordinary bowl of breakfast porridge. If the rolled oats packaging lists 10 g of fibre per 100 g, then 50 g of dry oats provides 5 g of fibre. Adding water increases the amount of porridge, but the amount of fibre stays the same.
One of the best-known reviews of the benefits is a series of systematic reviews and meta-analyses published in The Lancet in 2019. Commissioned by the World Health Organization, it summarised nearly 40 years of observational studies and clinical trials (Reynolds et al., 2019).
People who ate the most fibre had 15–30% lower all-cause and cardiovascular mortality than those who ate the least. They also had lower rates of coronary heart disease, stroke, type 2 diabetes and colorectal cancer. In randomised trials, higher fibre intake was associated with lower body weight, systolic blood pressure and total cholesterol levels.
For several outcomes, substantial benefits were already apparent at 25–29 grams per day. This is not an upper limit: the authors suggest that higher intake may offer additional benefits (Reynolds et al., 2019).
The data on disease incidence and mortality come from observational studies. These show an association, but do not prove that fibre caused the entire difference, because people who eat fibre-rich foods also differ in their other habits. Taken together with clinical trials, however, the findings provide good grounds for recommending adequate fibre intake (Reynolds et al., 2019).
Why does fiber make your stomach rumble?
Fiber consists mainly of carbohydrates that our digestive enzymes cannot break down in the small intestine. Some of it is broken down by microbes living in the large intestine. Fermentation produces gases such as hydrogen and carbon dioxide, and, in some people, methane too. Not all fiber ferments in the same way, but gas production is a natural part of this process (Carlsen & Pajari, 2023; Winham & Hutchins, 2011).
At the same time, these microbes also do useful work for the body. Fermentation produces short-chain fatty acids, such as butyrate, which the cells lining the large intestine use as an energy source.
So do beans inevitably make you bloated? In three studies, adults ate half a cup of beans or a comparison food, such as carrots or soup, every day. In the first week, about half of those eating pinto beans or baked beans reported passing gas more often, compared with about a fifth of those eating black-eyed peas (Winham & Hutchins, 2011).
In another trial lasting 12 weeks, 40 people ate pinto beans. Symptoms became less frequent over time in this trial too, but not for everyone: from week six through week twelve, 15–23% still reported them. Most adapted, but not everyone.
One more detail is worth noting. A small proportion of participants (3–11%) reported increased gas even when they ate the comparison food. The authors discussed how expectations might influence perceived symptoms (Winham & Hutchins, 2011).
How long does it take to adapt?
Adaptation can take weeks, but there is no fixed timeline. In one six-week study, adults with excess body weight received arabinoxylan isolated from corn bran every day alongside their usual diet: 25 grams for women and 35 grams for men. This was the amount of the supplement, not their total daily fibre intake. During the first three weeks, ratings of gas, bloating and abdominal pain were higher than in the control group, but by the end of the study they had, on average, returned to baseline (Deehan et al., 2024).
This does not happen with every type of fibre. In an eight-week trial, 98 healthy young adults received either yoghurt and bars containing a total of 16 grams of oligofructose, or similar foods without added fibre. Among those receiving oligofructose, average fibre intake rose from 12 grams to 24 grams per day. Symptoms were mostly mild to moderate, but did not decrease over the eight weeks, and one participant withdrew from the trial because of abdominal discomfort (Dahl et al., 2014).
Adaptation is not guaranteed, and it also depends on the type of fibre. If your stomach remains unsettled, it is worth reducing the amount or trying a different source rather than putting up with discomfort at all costs.
Do all fibre supplements work the same way?
Both may be labelled “fibre” on the packaging, but their effects may not be the same. In a Stanford study, 18 adults tried two purified fibres: arabinoxylan, found in whole grains, and long-chain inulin, found in foods such as onions and chicory root. Each was taken for three weeks, with the daily dose increased each week from 10 grams to 20 and then 30 grams (Lancaster et al., 2022; Stanford Medicine, 2022).
The results went in two different directions. LDL cholesterol decreased in many participants taking arabinoxylan. With the higher dose of inulin, however, certain markers associated with inflammation increased, and three participants had elevated levels of the liver enzyme ALT. This may indicate liver cell damage, but on its own it is not a diagnosis (Lancaster et al., 2022).
The study was small, used high supplement doses and included people with insulin resistance. Inulin manufacturer BENEO has disputed the conclusions, suggesting that the changes may instead have resulted from fluctuations in participants’ body weight, insulin resistance or high baseline cholesterol (FoodNavigator, 2022). Foods and supplements were not compared, so the trial does not show that inulin in everyday foods is dangerous. It does, however, show why findings for one fibre cannot automatically be applied to another.
There is no need to take a supplement just because it is a trend. Everyday foods provide other nutrients as well as fibre, and a supplement’s potential benefits should be assessed based on the specific goal, dose and tolerability.
Does counting plants make sense?
Advice to eat at least 30 different plant foods a week is also circulating on social media. It comes from an observational study by the American Gut Project, in which people who ate more than 30 plant species a week had a more diverse gut microbiota than those who ate up to ten species (McDonald et al., 2018). This is an association, and the researchers themselves say that its impact on health cannot yet be assessed with certainty (University of Illinois, 2018).
In an NPR story, University of Illinois nutrition professor Hannah Holscher suggests five different sources of fibre a day as a practical goal (Godoy, 2026). Take this as a reminder to vary your diet, not as a new mandatory target. The thirtieth plant added to your salad does not flip a separate health switch in your gut.
Who should be especially careful?
If you have irritable bowel syndrome, Crohn’s disease or ulcerative colitis, the amount and type of fibre that suit others may not be right for you. It is worth discussing any major changes with a doctor or clinical nutritionist first (Cohen, 2026). The same applies if abdominal symptoms are severe, persist or are accompanied by other symptoms: in that case, you should see a doctor.
What should you keep in mind in practice?
Add fibre gradually. Start with a smaller portion and increase the amount based on how you feel.
Try different sources. If one food causes discomfort, it does not mean you need to give up all fibre-rich foods.
Drink enough water. Not getting enough fluids can make constipation worse.
Summary
Eating more fibre is a sensible change for many people. Higher intake is associated with a lower risk of disease and death, and clinical trials have shown benefits for several health markers. But increasing your daily intake as quickly as possible does not guarantee better results, because your gut needs time to adjust, not all fibres behave the same way, and a supplement is not the same as the food on your plate.
If you have been eating little fibre, you do not need to overhaul your entire diet tomorrow. Add berries to your porridge, try a small amount of beans in soup, or swap a grain product for a wholegrain version. You do not need to sit at work feeling like a balloon just to clock up grams of fibre.
This article is not a substitute for personalised nutritional or medical advice.
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