Children who are clumsy and have poor hand control may be more likely to become obese as adults, researchers have found.

The study was based on tests of about 11,000 people in Britain who were tested for hand control, co-ordination and clumsiness at age seven and 11, and were then followed until age 33.

The seven-year-olds were assessed by their classroom teachers who also supervised physical education classes. At age 11, some participants were assessed by medical officers. Heights and weights were measured, and tests were given to measure the ability to copy a simple design accurately or pick up matches quickly.

In Wednesday's issue of the British Medical Journal, researchers said the risk of becoming obese in adulthood was more than doubled in seven-year-olds who "certainly" showed poor hand control during the tests and tripled for those who were affected by clumsiness, compared with children who were easily able to perform the tasks.

The findings add to evidence linking poorer cognitive function in childhood to obesity and Type 2 diabetes in adults, the researchers said.

Prof. Scott Montgomery of the Karolinska Institutet in Stockholm and his colleagues at Imperial College London in England said they purposely chose measurements of fine hand control such as picking up matches, rather than those likely to be influenced by participating in sports, such as catching balls.

While it is often assumed that the cognitive impairments seen in adult obesity are a consequence of excess weight, that could be putting the chicken before the egg, the researchers say.

"Obese adults and those with adult onset Type 2 diabetes mellitus may already have lower levels of cognitive function in childhood, consistent with a subtle developmental impairment," the study's authors wrote.

Most of the children were not heavier than average, so it's unlikely that people who are overweight already become clumsy. The findings held true after adjusting for childhood body mass and family social class.

"This study cannot identify the specific biological processes linking poorer physical control and co-ordination in childhood with later obesity. However, it suggests that some of the processes associated with poorer neurological function in obese adults have their origins in childhood," the study concluded.

The researchers speculated that factors such as smoking during pregnancy or lack of exercise in childhood could impair the development of physical control and co-ordination, and could also increase the risk of obesity later in life.