The increased risk of obesity in children aged 18 months to four years who are looked after by extended family was found to be 50 per cent. The risk refers to children when they are between the ages of four and ten.
The study, which was recently published in the Journal of Pediatrics, followed more than 1,600 children born between 1997 and 1998 in Quebec from the age of one-and-a half to ten years.
The children were classified according to the type of care in which they had spent the most time: at a daycare centre (30 per cent), 'family-based', that is, a childminder, (35 per cent), with a relative (11 per cent), with a nanny (5 per cent), or with their parents (19 per cent).
However, it is unclear why childcare arrangements would be associated with weight gain. Lead researcher Dr Marie-Claude Geoffroy said, 'This difference cannot be explained by known risk factors such as socioeconomic status of the parents, breastfeeding, body mass index of the mother, or employment status of the mother.'
Tam Fry, spokesperson for the National Obesity Forum, said, 'When children are cared for on a daily basis outside the family home, there is a propensity for children to receive less than nutritious food, and that will cause the problem.'
He added, 'In England the nutritional guidelines, which were introduced in January, should be compulsory because nutritional standards are too sensitive to be left to voluntary take-up.'
Previous studies from the US and Europe have also reported an increased risk of overweight or obesity in those attending childcare compared with those in parental care.
The latest figures, for 2010/11, from the National Child Measurement Programme, which measures the height and weight of school children in England, show that 9.4 per cent of children aged four to five were obese.The obesity rate more than doubled to 19 per cent among tento 11-year-olds.
Samantha Old, chair of the Association of Paediatric Chartered Physiotherapists, a professional network of the Chartered Society of Physiotherapy dealing in the care of young people, said, 'We need to be cautious about applying the findings of a Canadian study to the UK. Tackling obesity is a significant challenge which health professionals in the UK, including physiotherapists, are striving to meet by taking a multi-disciplinary approach of encouraging improved diet, more active lifestyle and better education.'