What not eating enough fibre does to your body

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 to 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 trying sitting in the right position if you find things are getting stuck, but plenty of fibre will help keep things moving.

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 to 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 out your energy levels. Plus fibre also has the added benefit of improving the quality of your sleep.

4. Gives you bumpy eyelids

Soluble fibre (the kinds 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.

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, therefore higher in sugar and fat. Without fibre you’re less likely to feel satisfied and 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, 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.

The good news is that it’s easier than you think to increase your fibre intake. 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 or veggie sticks and chuck in an extra handful of vegetables or legumes to your meals. Set yourself a challenge to reach the 5-a-day, or 30 plants per week, to ensure a wide variety of foods (and types of fibre). Your body will thank you!

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.

All health content on bbcgoodfood.com is provided for general information only, and should not be treated as a substitute for the medical advice of your own doctor or any other health care professional. If you have any concerns about your general health, you should contact your local health care provider. See our website terms and conditions for more information.