Easy-win habits
How Much Fiber Do You Need a Day?
By Midline. First published . Last reviewed .
The question
How much fiber should you eat a day?
Short answer
Aim for about 30 grams a day. Sarah Berry, Giles Yeo and Vonda Wright all give that number. Most people eat far less, so add it a bit at a time and see how your gut feels.
How much fiber do adults need?
About 30 grams a day. Sarah Berry, Giles Yeo and Vonda Wright all give that number:
| Expert | Fiber a day |
|---|---|
| Giles Yeo | 30 g a day, about double what most people eat |
| Sarah Berry | At least 30 g a day |
| Vonda Wright | About 30 g a day, which feeds your microbiome and slows digestion |
The practical answer is the same: most of us need a lot more than we eat now.
How much do most people actually get?
Far less.
Two Diary of a CEO episodes in our library make the same point. On a January 2025 episode about meal timing, Sarah Berry said we should get at least 30 grams and that people in the UK and US average about 20. In a clip in a December 2023 compilation episode, Giles Yeo said to aim for 30 grams, about double what most people eat.
Why does plant variety matter?
On a January 2026 episode about gut health, Tim Spector's angle was the gut microbes: he says to eat a wide variety of plants, about 30 a week, to feed as many kinds of gut microbes as you can.
How do you add more fiber?
Go slowly. Add fiber a bit at a time and see how your gut feels. Some people do not do well on a lot of it. On a September 2026 episode on sleep and energy, Andrew Huberman described Stanford work in which eating more fiber raised inflammatory markers in many people (the study, in Cell). He says too much fiber can be bad for some people.
Easy ways to add plants: beans or lentils in a stew, berries, nuts, or one new vegetable.
We suggest one new addition a week, so you can see how your gut feels. If you're eating your vegetables first, you're already doing part of this.
Should you use a fiber supplement instead?
We start with food: the plant variety above.
If you take a fiber supplement like psyllium and take any medicine, ask your pharmacist how to space them.
Check first: follow the label. If you take any medicine, are pregnant or breastfeeding, or have a kidney or liver condition, ask your pharmacist or doctor before adding a fiber supplement. If you have IBS or another bowel condition, talk to your doctor before adding a lot of fiber.
Try this today
Add one plant to today's meals: a new vegetable, fruit, bean or lentil. Add fiber a bit at a time and see how your gut feels.
Frequently asked questions
Is 30 grams of fiber a day too much?
No. Sarah Berry, Giles Yeo and Vonda Wright all give about 30 grams a day. If you're well below it now, add it a bit at a time rather than all at once.
What happens if you eat too much fiber at once?
Some people do not do well on a lot of it. Andrew Huberman described Stanford work in which eating more fiber raised inflammatory markers in many people. Add it a bit at a time and see how your gut feels.
Should I take a fiber supplement instead?
If you take a fiber supplement like psyllium and take any medicine, ask your pharmacist how to space them.
What if fiber makes my IBS worse?
Some people do not do well on a lot of fiber, so add it a bit at a time and see how your gut feels. If symptoms keep up, see your doctor.
Sources
- Sarah Berry on The Diary Of A CEO. Sarah Berry, The Diary Of A CEOWe should get at least 30 grams of fiber a day; most people in the UK and US average about 20.
- Giles Yeo on The Diary Of A CEO. Giles Yeo, The Diary Of A CEOAim for 30 grams of fiber a day, about double what most people eat now.
- Vonda Wright on The Diary Of A CEO. Vonda Wright, The Diary Of A CEOFiber at about 30 grams a day feeds your microbiome and slows digestion.
- Tim Spector on The Diary Of A CEO. Tim Spector, The Diary Of A CEOEat a wide variety of plants, about 30 a week, to feed as many kinds of gut microbes as you can.
- Andrew Huberman on The Diary Of A CEO. Andrew Huberman, The Diary Of A CEODescribed Stanford work in which eating more fiber raised inflammatory markers in many people. He says too much fiber can be bad for some people.
- Gut-microbiota-targeted diets modulate human immune status (Wastyk et al.). Cell, 2021, the study Andrew Huberman describedThe Stanford work Andrew Huberman described on fiber and inflammatory markers.
All sources across the site are listed on the sources page.
Watch the episode
- Episode on meal timing, snacking and food quality (Sarah Berry, The Diary Of A CEO, )
- Compilation episode on belly fat habits (Giles Yeo, The Diary Of A CEO, )
- Episode on healthy ageing (Vonda Wright, The Diary Of A CEO, )
- Episode on gut health and fermented foods (Tim Spector, The Diary Of A CEO, )
- Episode on sleep and energy (Andrew Huberman, The Diary Of A CEO, )
Last reviewed . Educational only, not medical advice. Check with your pharmacist if you take medication.
We draft articles with AI help. A reviewer checks every health statement against the expert's own words in the video before it goes up.
Related articles
- Easy-win habits
Strength Training After 40: How Often Is Enough?
Two to three days a week is the range our experts give, with a whole-body routine. And you can still build muscle as you get older. - Supplement timing and quality
Best Time to Take Fish Oil: With a Meal
Take fish oil with a meal. Plus keeping the bottle fresh, and what to check first if you take a blood thinner. - Supplement timing and quality
Best Time to Take Vitamins: Build a Simple Schedule
Vitamin D goes with a meal that has some fat, fish oil with a meal, and creatine at a time you'll remember. A few need space from medicines. How to group yours into a simple daily schedule.