As a rule of thumb, the skins of fruit and veg pack more fibre than the insides.

Eating a kiwi with the skin on , external provides 50% more fibre than having a peeled one, for example.

For their study, the scientists at King's College London analysed 12 raw or uncooked fresh foods - beetroot, bell pepper, broccoli, butternut squash, cauliflower, celeriac, curly kale, fennel, kiwi fruit, leek, pineapple and watermelon.

They found many discarded parts contained more fibre than the sections people typically eat.

For example:

watermelon rind contained 2.10g of fibre per 100g – roughly equivalent to the fibre in a slice of wholemeal bread

butternut squash skin and seeds contained 9.25g per 100g – nearly as much fibre as a bowl of bran flakes

pineapple skin and core contained five times more fibre than the flesh

broccoli stalks contained fibre, although a bit less than the florets

Fibre is essential for your gut to work properly and helps prevent constipation.

Project lead Dr Rachel Gibson said the…