Eighty per cent of school children aged four to 11 years were weighed and measured in England in 2006/7 as part of the DoH national child measurement programme.
Of those measured, 22.9 per cent of children aged four to five were overweight or obese, and 31.6 per cent of those aged 10-11 were overweight. At all ages, boys were more likely to be obese than girls.
Participation has vastly improved, compared with the 48 per cent uptake in the previous, and first, year of the scheme.
But Tam Fry, chairman of the Child Growth Foundation, said the DoH targets fail to go far enough.
'The DoH has achieved the target of 80 per cent that it set itself, but it should be aiming to weigh all schoolchildren,' he said.
'It is the 20 per cent who are overweight children that do not want to be weighed that they need to focus on.'
Children aged one to four should also be weighed because this is an important time in child development, said Mr Fry.
The National Obesity Forum (NOF) wants a childhood register added to the obesity domain of the quality framework.
Dr Colin Waine, chairman of the NOF and a GP in County Durham, said: 'GPs should be measuring the BMI of children from the age of one and then following this up throughout childhood.
'We are measuring children when they have become overweight, making it much harder to lose the weight,' he added.
Last month, the DoH launched a £372 million anti-obesity strategy, including healthier school meals and bicycle lanes.