What’s the scale of the problem?
he proportion of the world’s population who are obese has tripled since 1975, according to the World Health Organisation (WHO). It reckons about 650 million adults worldwide were obese in 2016, defined as having a “body mass index” of more than 30, and projects that the number will be a billion by 2025. (BMI is calculated by dividing weight in kilograms by the square of height in metres. A “normal” BMI is 18.5 to 25; overweight is 25 to 30.) In high-income Western countries, almost a third of the
