Nearly a quarter of British under-fives are overweight or obese, the European Congress on Obesity has heard
The study, presented in Prague, found that the UK has the second-highest proportion of overweight children out of the 28 countries that were able to provide data - 23.1%
Ireland came top of the list, with 27.5%.
Britain was followed by Albania (22%), Georgia (20%), Bulgaria (19.8%) and Spain (18.4%), reported The Guardian.
At the other end of the scale, Kazahkstan had the lowest obesity rate (0.6%), followed by the Czech Republic (5.5%) Belgium (7%) and Sweden (8%).
Another study, by Leeds Beckett University, found that children as young as six are suffering dissatisfaction with their bodies, with girls scoring higher in this area than boys.
More than 300 pupils (52% of them boys) from eight primary schools in Leeds took part in the study.
The study's lead researcher, Prof Pinki Sahota, said: "The results suggested that body shape dissatisfaction and dietary restraint behaviours may begin in children as young as six to seven years old, and there is an association with increased BMI.
"Obesity prevention programmes need to consider psychological wellbeing and ensure that it is not compromised. Further research should be conducted on how interventions can help improve psychological well-being in this age group."
Dr João Breda of the World Health Organisation's regional office for Europe, who was involved in the first study, said: "Evidence suggests that early intervention, before five years of age, is necessary if the trajectory to overweight in children is to be arrested and action needs to be taken to have consistent surveillance on this specific population."