How Much Fibre Do You Need a Day, and How to Get It
UK guidance says adults should aim for 30g of fibre a day. According to the NHS, most adults eat only about 20g, so the typical gap is around a third. You close it by building meals around wholegrains, beans and lentils, vegetables, fruit with the skin on, and nuts and seeds, and by increasing intake gradually over two or three weeks with plenty of fluid alongside. That is the whole answer. The rest of this piece is about how to do it in an ordinary London week, without a spreadsheet and without spending the afternoon uncomfortable at your desk.
Where the 30g figure comes from
The 30g target was set by the government’s Scientific Advisory Committee on Nutrition in 2015, after a review of the evidence linking fibre intake with lower risk of heart disease, stroke, type 2 diabetes and bowel cancer. It applies to adults and to teenagers from 16. Younger children need less: the guidance steps up from 15g a day for two to five year olds, to 20g for five to eleven, and 25g for eleven to sixteen.
It is worth being clear about what “fibre” means on a UK label. It refers to the parts of plant foods your small intestine cannot digest, which travel on to the large intestine. Some of it holds water and softens stools; some of it is fermented by gut bacteria. You do not need to track the types separately. Eat a range of plant foods and you get a range of fibres.
The NHS page on getting more fibre into your diet is a sound, short reference if you want the official version.
Why someone who trains should care
Most of the clients I coach come to me thinking about protein, which is fair. Fibre gets less attention, but it does a lot of quiet work in a training week.
- Fullness. High-fibre meals tend to be bulkier and slower to eat. If you are trying to lose fat, a lunch of lentil soup and wholemeal bread keeps most people going longer than a white baguette with the same calories.
- Steadier energy. Wholegrain carbohydrate alongside protein makes a mid-afternoon dip less likely than refined carbohydrate on its own. That matters if you train at 6pm.
- Regularity. People who shift to a higher-protein diet sometimes eat fewer plants without noticing. Constipation follows. Fibre and fluid fix that.
- Long-term health. This is the reason the target exists in the first place, and it is the reason I care about it for clients over 30.
What 30g looks like on a plate
The figures below are rough and vary by brand and portion, so check the label where there is one. In the UK, “high fibre” on a pack means at least 6g per 100g, and “source of fibre” means at least 3g per 100g. Those two thresholds are the quickest shortcut in a supermarket aisle.
| Meal | Example | Roughly |
|---|---|---|
| Breakfast | Porridge made with 40-50g oats, a handful of berries, a spoon of ground flaxseed | 7-9g |
| Lunch | Two slices of wholemeal or seeded bread, a bowl of bean or lentil soup, an apple | 10-13g |
| Snack | A small handful of almonds, or carrot sticks with hummus | 2-4g |
| Dinner | Chicken or tofu, brown rice or wholewheat pasta, two portions of vegetables, a spoon of peas or chickpeas | 8-11g |
That lands somewhere around 27 to 37g. Notice that none of it is unusual food. The difference between 18g and 30g is mostly swaps, not additions.
The swaps that do most of the work
If you change only four things, change these:
- White bread to wholemeal or seeded. Two slices a day, every day, adds up faster than any single “superfood”.
- Add a tin of beans or lentils to something you already cook. Chilli, curry, ragu, soup, a tray of roast vegetables. Half a tin across two portions is barely noticeable in taste and adds several grams each.
- Leave the skins on. Potatoes, apples, pears. Peeling throws away a meaningful share of the fibre.
- Start the day with oats or a high-fibre cereal. Look for the 6g per 100g line on the label.
Frozen vegetables count as much as fresh, and they keep. A bag of frozen peas and one of mixed vegetables in the freezer removes the most common excuse.
How to increase fibre without discomfort
This is where most people go wrong. They read that they are 10g short, add bran, beans and a large salad on the same Monday, and spend Tuesday bloated. They conclude fibre does not suit them.
A more sensible approach:
- Week one: one change only. Usually the bread or the breakfast.
- Week two: add beans or lentils to two dinners.
- Week three: fruit and nuts as default snacks, vegetables at lunch as well as dinner.
- Throughout: drink more water. Fibre that holds water needs water to hold. The NHS makes this point specifically.
Some wind in the first week or two is normal as gut bacteria adjust. Persistent pain, a sudden change in bowel habit that lasts more than a few weeks, or blood in your stool are not things to manage with diet. Check with your GP first if you have IBS, inflammatory bowel disease or any diagnosed digestive condition, because the advice for those can differ from the general guidance.
Fibre around training sessions
Fibre slows digestion, which is useful most of the day and less useful in the hour before hard training. A large bowl of bean chilli at 5pm before a 6pm session of squats and intervals on the air bike is a poor plan. Keep the big fibre meals away from the session and have something simpler beforehand if you need it. We cover timing in more detail in what to eat before a workout.
After training, fibre is fine. A normal balanced meal with protein, carbohydrate and vegetables is all you need, as set out in our piece on the post-workout meal.
Common mistakes
- Relying on supplements. Psyllium husk has its uses, but it gives you one type of fibre and none of the other things that come with whole plant foods. Food first.
- Trusting “multigrain”. A loaf can be multigrain and still mostly white flour. “Wholemeal” or “wholegrain” as the first ingredient is what you want.
- Juicing. Most of the fibre stays in the juicer. Eat the fruit.
- Going high-protein and low-plant. Shakes, chicken and eggs, very little else. Protein matters, and you can see how much in our guide to how much protein you need to lose fat, but it should sit next to plants, not replace them.
- Counting to the gram. You do not need to. Hit the four swaps and fruit and vegetables at most meals and you will be close.
How I handle this with clients
When someone starts private 1-1 training with me in the basement studio on Archway Road, nutrition is part of the first conversation, but I rarely open with a calorie target. I ask what a normal Tuesday looks like. Breakfast is often coffee, lunch is a meal deal, dinner is decent. Fibre is usually the easiest gap to see and the easiest to fix, and fixing it tends to make everything else, including appetite control, a bit easier.
We track progress with the InBody body composition scanner and with how training is going, not with food diaries forever. If you want to see how that fits into a coached programme, the personal training page explains what sessions include.
Questions we get asked
Can you eat too much fibre?
For most healthy adults eating whole foods, it is hard to overdo it in a way that causes harm, but increasing too quickly causes bloating and wind. Go gradually and drink enough. If you have a digestive condition, take advice from your GP or a dietitian.
Does fibre help with weight loss?
Not directly, but high-fibre meals tend to be more filling for the same calories, which makes a calorie deficit easier to live with. That is the practical benefit.
Are fibre supplements as good as food?
They can help with regularity, but they do not replace the range of fibres and nutrients you get from wholegrains, pulses, fruit and vegetables. Use them as a backstop, not a strategy.
Does fruit count if it is dried or blended?
Dried fruit keeps its fibre but is easy to overeat and sticks to teeth, so keep portions small. Smoothies keep more fibre than juice, but whole fruit is still the better choice.
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