Can I just comment about biometric data? Weighing children and taking measurements is an area of great sensitivity. Certainly, probably the most reliable measurement of adiposity is waist measurement. This doesn't require coming into quite close contact with children. Girls in particular are very sensitive about that.
You also have to be very careful about the way in which height-for-weight data is used and whether children are classified or labelled as obese or overweight. In the U.K., we are using new international standards for relative body weight, and those standards tend to slightly overclassify children into the overweight or obese classification when compared with the previous systems.
There is no doubt that waist sizes have been going up in the U.K. That's quite an easy one, in terms of actually knowing the waist sizes of the trousers that children have. That's a way of monitoring this.