Fibre on a GLP-1: Food, Fluids and Simple Swaps

Quick answer: UK guidelines recommend 30g of fibre a day, and smaller portions on a GLP-1 like Mounjaro or Wegovy can make that harder to reach. Build meals around vegetables, pulses, oats and wholegrains, increase fibre slowly, and drink plenty of fluids alongside it. If you're having ongoing bowel problems, speak to your pharmacist or prescriber rather than self-treating.

Why fibre drops on a GLP-1

Fibre-rich foods like vegetables, beans and wholegrains are bulky and filling. When your appetite is reduced, they're often the first thing left on the plate. Add in lower fluid intake, and it's easy to see why many people on GLP-1 medicines notice changes in their digestion.

How much fibre do you need?

The UK recommendation is 30g of fibre per day for adults. National surveys show most adults eat closer to 20g, so the average person is already short before any change in appetite.

Easy high-fibre swaps that don't add much volume

Instead of	Try	Why it helps
White toast	Wholegrain or seeded toast	More fibre in the same portion
Sugary cereal	Porridge oats	A good source of soluble fibre
Plain rice	Rice mixed with lentils or beans	Adds fibre and protein together
Crisps	A small pear or apple with the skin on	Fibre plus fluid
Cream soup	Vegetable and lentil soup	Fibre and fluid in one bowl

Don't forget fluids

Fibre works best with water. Increasing fibre without increasing fluids can leave you feeling uncomfortable. Aim for around 6 to 8 glasses of fluid a day, and sip regularly if large drinks make you feel too full.

Increase it gradually

Jumping from 15g to 30g overnight can cause bloating and wind. Add a few grams every few days so your gut can adjust.

When a fibre top-up can help

If food alone isn't getting you close to 30g, a fibre supplement is one way to bridge the gap. Our Fibre Pro+ 3-In-1 Complex is designed to slot into your daily routine alongside a varied diet. Take it with a full glass of water, and if you take other medicines, ask your pharmacist about timing, as fibre can affect how some medicines are absorbed.

When to speak to a professional

Constipation, diarrhoea and stomach discomfort are known side effects of GLP-1 medicines. A fibre supplement isn't a treatment for these. If symptoms are severe, ongoing, or you notice blood in your stool or severe stomach pain, contact your GP or prescriber.

FAQs

How much fibre should I eat on Mounjaro?

The general UK target of 30g a day still applies. Build up gradually and drink plenty of fluids.

Can I take a fibre supplement with Wegovy?

Many people do, but ask your pharmacist about timing if you take other medicines.

What are the best high-fibre foods?

Oats, beans, lentils, chickpeas, wholegrain bread, berries, pears, apples with the skin on, and most vegetables.

Reviewed by John Lebach (Nutrition Coach) and Numan Caan (Senior Sports Scientist)

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This article is for general information only and isn't medical advice. Food supplements should not be used as a substitute for a varied, balanced diet and a healthy lifestyle. If you take prescribed medication, are pregnant or breastfeeding, speak to your GP or pharmacist before starting a supplement.