Strength training

Strength training is any movement in which your muscles work against resistance – your own body weight, a resistance band, a dumbbell or a crate of bottled water. It doesn't just make you strong; it also keeps your bones dense, your joints stable and your metabolism active.

It plays a key role in weight loss: in a calorie deficit, the body would otherwise lose not only fat but also muscle. Strength training plus enough protein (the German Nutrition Society, DGE, gives 0.8 grams per kilogram of body weight as a baseline; when you're losing weight and training, it can be more) signals to your body that it should hold on to its muscle. More muscle mass also means a slightly higher basal metabolic rate (the energy your body uses at complete rest) – around the clock.

The WHO recommends that adults do muscle-strengthening exercises for all major muscle groups on at least two days a week: legs, glutes, back, chest, shoulders and abdomen. A simple framework for beginners: two to three sets of eight to twelve repetitions, with the last two feeling hard but still performed with clean form. Leave about 48 hours between two sessions that work the same muscles.

You don't need a gym for this. Squats, lunges, push-ups against a wall or a table and rows with a resistance band cover your whole body. What matters is that you make the exercises harder over time – this is called progressive overload.

Children and teenagers can do strength training too, ideally in a playful way using their own body weight and under supervision: climbing, monkey bars, wheelbarrow walks. Maximum weights only belong in supervised training plans for advanced athletes. Older people benefit enormously too, because from around the age of 30, without training, we lose around three to eight per cent of our muscle mass per decade.