The Daily Mile started in a primary school in central Scotland six years ago. Now it has spread to 3,600 schools in 35 countries.
It puts an average 1.4kg on the weighing scales.
The Body Mass Index is used to assess the risk of lifestyle diseases, but the relationship between BMI and chronic illnesses remains far from simple.
Of the 22,713 weight loss operations performed in 2014-15, about 90% were performed in private hospitals, highlighting the difficulty in accessing this type of surgery through the public system.
Horrors of job discrimination.
To tackle obesity, the NHS is experimenting with financial incentives, dieting clubs and free exercise classes. But what about prescribing digital fitness trackers?