Dietary fibre

Fibre is the part of plant foods that your small intestine can't digest – and that's exactly what makes it so valuable. It swells in your stomach and fills you up, slows the absorption of sugar into the blood, keeps your digestion moving and feeds the beneficial bacteria in your gut. The German word for fibre, “Ballaststoffe”, literally means “ballast” – a misleading name, because it's anything but dead weight.

There are two kinds: soluble fibre (found in oats, pulses, apples and linseed, for example), which forms a kind of gel in water and has a beneficial effect on blood sugar and cholesterol, and insoluble fibre (in wholegrains, bran and vegetable skins), which adds bulk to stools and speeds up their passage through the gut. Both kinds belong on your plate.

The German Nutrition Society (DGE) recommends that adults eat at least 30 grams of fibre a day; according to Germany's National Nutrition Survey, most people in Germany only manage around 20 grams. Children need less, in line with their energy needs – roughly 10 grams per 1,000 kcal. Some examples: 100 grams of wholemeal bread provides about 8 grams, a portion of cooked lentils around 8 grams and an apple with its skin about 3 grams.

When you're trying to lose weight, fibre is key: it adds volume to meals for very few calories and prevents the blood sugar spikes that trigger cravings. Switching from white flour to wholegrain, eating vegetables with every meal and having pulses two or three times a week is often enough to reach the target.

A tip: increase the amount gradually over a few weeks and drink enough – otherwise your gut may protest with wind and bloating. Fibre powders and pills are unnecessary for healthy people.