Fibre Intake Calculator

Find your daily fibre target based on age, biological sex, and calorie intake. Understand the soluble vs insoluble split and which foods to eat to reach your goal.

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Why Fibre Is the Most Underrated Nutrient

Despite overwhelming evidence of its health benefits, fibre is the nutrient most consistently under-consumed in Western diets. The average adult eats 10–15g/day, less than half the recommended intake.

Fibre and Gut Health: The Microbiome Connection

Your gut microbiome, the 100 trillion bacteria living in your intestines, is fed primarily by fibre. Different bacterial species ferment different types of fibre, producing short-chain fatty acids (SCFAs) including butyrate, which:

Fuel colonocyte (gut lining cell) repair and maintenance
Reduce gut inflammation
Improve insulin sensitivity
Signal satiety hormones in the brain

A diverse plant-based diet with 30+ different plant foods per week (studies show this number is associated with optimal microbiome diversity) is the most effective strategy for gut health.

Fibre and Weight Management

Increasing dietary fibre is one of the most effective and sustainable weight management strategies. A 2019 systematic review found that increasing fibre intake to recommended levels produced clinically meaningful reductions in body weight without other dietary changes.

The mechanisms: reduced calorie density of high-fibre foods, improved satiety signalling, improved insulin sensitivity reducing fat storage signals, and reduced absorption of some dietary fat in high-fibre contexts.

Frequently Asked Questions

How much fibre should I eat per day?

The recommended adequate intake is 25g/day for women and 38g/day for men (USDA DRI), or 14g per 1,000 kcal of food consumed. Most people eat only 10–15g/day, less than half the recommended amount. Higher fibre intake is consistently associated with lower risk of cardiovascular disease, type 2 diabetes, colorectal cancer, and better weight management.

What is the difference between soluble and insoluble fibre?

Soluble fibre dissolves in water and forms a gel, it slows digestion, reduces blood glucose spikes, feeds beneficial gut bacteria, and lowers LDL cholesterol. Found in oats, beans, apples, and psyllium. Insoluble fibre does not dissolve, it adds bulk to stool and promotes regular bowel movements. Found in wheat bran, vegetables, and wholegrains. Both are important; a varied diet with plenty of plants provides both.

Why does increasing fibre cause bloating?

Gut bacteria ferment fibre, producing gas. When you increase fibre intake rapidly, bacteria populations haven't adapted to the increased fermentation load, resulting in excess gas and bloating. This is temporary. Increase fibre gradually (3–5g per week) to give gut bacteria time to adapt. Also drink more water, fibre absorbs water, and dehydration worsens constipation when fibre is increased.

Does fibre help with weight loss?

Yes, through multiple mechanisms. Soluble fibre increases satiety hormones (GLP-1, PYY) and slows gastric emptying, reducing hunger between meals. High-fibre foods are typically high volume and low calorie density. Fibre feeds beneficial gut bacteria that produce short-chain fatty acids, which improve insulin sensitivity and may reduce fat storage. Studies consistently show higher fibre intake predicts lower bodyweight.

How it's calculated: this tool uses established, published equations. See the full calculator methodology for the formulas and assumptions behind it.

Results are estimates for general guidance, not medical advice. See our disclaimer, and speak to a qualified healthcare professional before making medical or dietary changes.