Fats

Fat is the most energy-dense nutrient – and yet it's indispensable. One gram provides 9 kcal, more than twice as much as carbohydrates or protein. Your body needs fat as a building material for every cell wall, for hormones, as a protective cushion for your organs and to be able to absorb vitamins A, D, E and K at all. Fat also carries flavour – that's why food tastes richer with it.

Fats are made up of fatty acids, and the type makes all the difference. Saturated fatty acids are found mainly in butter, sausages and cold cuts, fatty meat, cream and many ready-made products; too much of them raises LDL cholesterol – the “bad” cholesterol that can build up in the walls of blood vessels. Unsaturated fatty acids from rapeseed and olive oil, nuts, seeds, avocado and fish are good for the heart and blood vessels. Two of them – linoleic acid and alpha-linolenic acid – are essential: the body can't make them itself.

The German Nutrition Society (DGE) recommends that adults get around 30% of their energy from fat, with no more than 10% from saturated fatty acids. At 2,000 kcal, that's about 65 grams of fat a day – more than many people think, but quickly reached: a tablespoon of oil already contains 10 grams, a handful of nuts around 15 grams.

When you're trying to lose weight, it pays not to demonise fat but to use it wisely: cut down on the hidden fat in processed meats, crisps, pastries and sauces, and consciously enjoy visible, good-quality fat. Low-fat doesn't automatically mean low-calorie – many “light” products replace fat with sugar.

Toddlers need proportionally more fat than adults, for example for brain development. Low-fat diet food has no place on a child's plate – whole milk, nut butter and good oil are exactly right for them.