With our diets made up of more processed foods – think: white bread, rice and pasta – and fewer whole fruit and vegetables, the resulting lack of fibre increases the likelihood of digestive, weight and chronic disease issues. No wonder then that the social media craze for fibremaxxing has prompted many of us to question whether we’re getting enough.
All about upping your fibre intake, fibremaxxing involves adding fibre-rich foods like prunes, wholegrains and beans to your diet or, when taken to extremes, boosting fibre further through supplements.
Discover our gut-friendly recipes, find out the more about fibremaxxing and why eating 30 plant foods a week supports your gut health.
Fibre might not be the most glamorous of nutrients, but it’s very much the unsung hero when it comes to keeping your body running smoothly. As tastes and food choices have changed, we’re eating more processed carbs and less fruit, vegetables and whole foods than ever. As a result, our fibre consumption has nosedived. In fact, dietary fibre intake across the globe is consistently lower than recommended amounts.
Unfortunately, there are knock-on effects for our health: fibre plays an important role in digestion, weight management and lowering the risk of heart disease, diabetes and some cancers. This article will explore the harmful short- and long-term impacts on our bodies of not getting sufficient dietary fibre. Read on to find out why your morning croissant would be better swapped for a bowl of porridge.
How much fibre per day should I be eating?
In the UK, the guideline is 30g of dietary fibre per day for adults, but the latest figures suggest the average current intake is only 16g. Recommendations are proportionately lower for children, with daily recommendations at 15g for those aged two to five, 20g for those five to 11 and 25g for those 11-16. In the US, the target is 25g per day for women and 38g for men, but most adults are averaging just 16g per day.
What are the symptoms of too little fibre?
1. Causes toilet troubles
Without enough fibre, the digestive process slows down. Fibre adds bulk to your poo and helps it move through the gut, helping prevent constipation. But, without it, you might find yourself spending more time in the bathroom, having a difficult time straining to pass a poo. Do try drinking more water and sitting in the right position if you find things are getting stuck, but plenty of fibre will help keep things moving.
Read more about why you may be constipated.
2. Can lead to piles
Piles or haemorrhoids are swollen veins in the lowest part of your rectum or anus. They can cause painful lumps around your bottom that might bleed and itch. They’re thought to be worsened by constipation and straining to go to the toilet. Eating more fibre helps soften the stool and reduces your risk of piles. Try to include more soluble fibre from oats, fruits and legumes.
3. Makes you feel fatigued
Low-fibre diets tend to include more processed foods, which are much higher in sugar. This causes your blood sugar levels to rapidly rise and fall. A similar pattern is experienced with energy levels: quick bursts of energy followed by fatigue and tiredness. Choose fibre-rich wholegrains for a slower release of sugars into the bloodstream, which will balance your energy levels. Plus, fibre has the added benefit of improving the quality of your sleep.
4. Gives you bumpy eyelids
Soluble fibre (the kind found in oats, beans and fruit) acts like a sponge, soaking up excess cholesterol and getting rid of it with other waste in your stools. If you aren’t eating sufficient fibre to carry out this function, you might find your cholesterol levels are on the rise. Among the symptoms of high cholesterol are yellowish patches on the skin or bumpy eyelids. However, ask your GP for a blood test for reliable detection.
Check out our guide on cholesterol testing.
5. Causes bad breath
Bad breath can arise from poor digestion or more chronic gut-related issues. Often a lack of bowel movements can be traced to a low-fibre diet. Constipation-related halitosis is a sign of a medical condition and can be indicated by the smell of excrement on the breath.
6. Can lead to weight gain
Fibre helps you to feel fuller for longer. Without it, you might find yourself snacking more – and grab-and-go snack foods tend to be ultra-processed and therefore higher in sugar and fat. Without fibre, you’re less likely to feel satisfied, so it’s easy to overeat, leading to unwelcome weight gain.
7. Causes mood swings
Fibre slows down how quickly you absorb sugar into your bloodstream. This means that, without fibre, blood sugar levels can rise quickly after eating and crash shortly after, leaving you feeling tired and cranky. You’re more likely to reach for another quick fix and the cycle continues. Research has also shown low dietary fibre is linked to an increase in anxiety and depression.
8. Gives you spots
Believe it or not, fibre even plays a role in your complexion. A low-fibre diet negatively affects the bacteria in the gut, depleting the production of anti-inflammatory compounds, which contribute to a healthy skin barrier via the gut-skin axis. So, when your digestive system isn’t running smoothly, the effects can show in the form of spots, acne or dry, dull skin.
9. Can lead to a painful condition called diverticulitis
This one might sound a little scary, but a potential result of insufficient fibre intake can be small pouches forming in the wall of your colon. If these pouches (called diverticula) become inflamed or infected, they can cause severe pain and discomfort. Diverticulitis is more common as we age, but ensuring your diet includes plenty of fibre can help keep things in check.
10. Leaves your gut microbiome out of whack
Another slightly scary-sounding one, dysbiosis occurs when the bacteria that live in the gut are out of balance. The gut is home to trillions of bacteria, commonly known as ‘probiotics’. Fibre serves as nourishment for probiotic bacteria to flourish. Without sufficient fibre, probiotic bacteria diminish, leading to a less-diverse gut microbiome. This imbalance, known as dysbiosis, can cause inflammation, digestive issues, fatigue and mood changes.
How can I smash the daily 30g target?
The good news is, it’s easier than you think to increase your fibre intake and achieve the daily target. That said, if you’re not used to eating much fibre, increase your intake slowly – over weeks rather than days – to avoid digestive discomfort. Think about things you can add into your current diet, rather than taking things away. For example, swap white bread for wholegrain or granary; add some berries or a chopped apple to your breakfast cereal; snack on nuts, unsalted popcorn or veg sticks; and chuck in an extra handful of vegetables or legumes to your meals. Set yourself a challenge to reach a minimum of five-a-day or 30 plants per week to ensure a wide variety of foods (and types of fibre). Your body will thank you!
Enjoyed this? Now read:
What is fibre?
10 cheap ways to get enough fibre
Does diet affect gut health?
How to improve your digestion
Top 15 probiotic foods to support gut health
This page was reviewed on 30 October 2025 by Kerry Torrens.
Jo is a registered nutritionist (RNutr) with the Association for Nutrition with a specialism in public health. Since graduating from the University of Westminster in 2010, Jo has worked in a variety of public and private contexts, delivering weight management programmes, community cookery projects, and corporate wellness packages. Alongside trying to grow more of her own fruit and veg at her allotment, Jo works as a Nutritionist and Health Coach for Second Nature. She has contributed articles to a number of nutrition websites, including BBC Good Food.
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