A new analysis by the Oxford-based Social Issues Research Council, which is funded by food companies as well as the government, shows that there has been only a slight rise in average child weights during the last eight years.
The findings are in stark contrast with reports from other health bodies.The International Obesity Task Force said last year that childhood obesity in Europe was 'out of control' and that 20 per cent of British children were overweight in 1998.
A government report on health released in November last year also warned that "if the rapid rise in childhood obesity in the last decade is taken into account, the predicted prevalence in children will be in excess of 50 per cent".
SIRC analysed data on average weights from the 2003 Health Survey for England. Their data showed that an average 15-year-old boy weighed 60.7kg in 2003, compared with just over 58.8kg in 1995.
A 15-year-old girl weighed on average just under 58.9kg in 2003 compared with 58.5kg in 1995.
"We can conclude from these figures that there have been no significant changes in the average weights of children over nearly a decade. This can be taken as evidence that there has been no 'epidemic' of weight gain, since an epidemic would certainly have affected average weights," write the researchers.
The findings could have major implications for food makers trying to target children with healthy foods.
"Banning advertising of 'junk food' to children and similar measures may be popular in some quarters but they are targeted at the wrong age group. Most weight gain occurs after children leave school, become even less active but have access to an ad-libitum food supply," say the researchers.
SIRC also challenged the way childhood obesity is estimated in the UK. Children are classed as obese if they fall into the top 5 per cent of the weight range for their age.
However they say that an international measurement using height/weight distribution across six countries including the UK is more accurate.The UK method suggests obesity rates in children aged two to 10 have increased from 9.6 per cent in 1995 to 15.5 per cent in 2003.
SIRC said the international measure - which it said was better because it took into account the increase in children's average height since 1995 - showed rates had increased from 3.9 per cent in 1995 to 6.75 per cent in 2003.
Dr Peter Marsh, co-director of SIRC, told NutraIngredients.com: "Clearly there have been increases in obesity but these are mostly in older populations."
The SIRC research shows that overall levels of adult obesity have risen significantly over the past 10 years, going from 13.2 per cent of men in 1993 to 22.4 per cent in 2003.
But the increase in obesity is not even across all ages, say the researchers, and public health efforts should therefore target the at-risk age groups rather than children.
Hans-Jörg Renk, spokesman for Nestle, said: "This does not mean that we will now stop working on obesity research. We have been focusing on this area for a long time, it is not something driven by reports on figures."