Obesity

Obesity is the medical term for severe excess weight: in adults, it starts at a body mass index (BMI) of 30. The WHO divides it into three classes: class I from a BMI of 30, class II from 35 and class III from 40. Since 2020, the German Bundestag (the federal parliament) has also recognised obesity as a chronic disease – as the WHO has done for a long time.

How common is it? According to the Robert Koch Institute (RKI), Germany's public health agency, around one in five adults in Germany lives with obesity; among children and teenagers aged 3 to 17, the figure is about 6%, according to the KiGGS study. For children, BMI isn't read as a fixed number but compared with age- and sex-specific percentiles: from the 97th percentile upwards, paediatricians speak of obesity.

Why does it develop? Not because of a lack of willpower. Genes, sleep, stress, medication, hormones and an environment full of ultra-processed foods all interact. Twin studies show that the tendency towards a certain weight is largely inherited – but what someone makes of it is still something they can shape.

Why does it matter? Fat around the abdomen in particular raises the risk of type 2 diabetes, high blood pressure, fatty liver disease, joint wear and tear and sleep apnoea. The good news: losing just 5 to 10% of your body weight measurably improves blood sugar, blood pressure and blood lipids – at 100 kg, that's 5 to 10 kg, not 30.

What helps? Guidelines recommend a combination of changes to your diet, more physical activity and new habits – in small, lasting steps rather than crash programmes. If that isn't enough in cases of severe obesity, the guidelines say medication or surgery may also be an option – it's best to discuss this with your doctor. With children, a diet is never on the table; the focus is on the whole family: cooking together, spending time outdoors together and letting growth do its work. If you'd like support, you'll find it at your GP surgery, through nutrition counselling or at specialist obesity clinics.