In this week's Scrubbing Up, Dr Gavin Sandercock argues there has been a well-meaning but misguided focus on obesity, while the harm caused by inactivity has been overlooked.
We are used to seeing reports warning of an "obesity time-bomb". But the extent of the problem is often exaggerated.
Figures for 2010-11, from the National Child Measurement Programme, suggest 9% of five- to six-year-olds are obese.
That equates to 2.7 children in each class of 30. In 1990, it was 1.5.