Researchers from Cancer Research UK's Health Behaviour Research Centre at University College London (UCL) filmed 254 twin children aged 10-12 eating a standard meal in their homes to test whether their speed of eating was related to the amount of fat they carried and whether eating rate was a heritable characteristic.
The results indicated that the children's eating rate was partly influenced by their genes, and that a faster eating rate was linked to a higher body weight in general, and with overweight twins eating the fastest, and eating more in a sitting.
Previous experiments have confirmed that faster eating is linked to eating more, but studies making the direct link between a faster eating rate and higher body weight have produced mixed findings.
Children were divided into three weight groups to compare eating rate within the normal range as well as between obese and normal groups. The groups were: obese-overweight, higher-normal weight and lower-normal weight.
The researchers found that the overweight group ate significantly more than the other two groups. The overweight group ate the fastest at 4.3 bites per minute, followed by the higher-normal weight group which ate on average 4.1 bites per minute. The lower-normal weight group ate slowest at 3.8 bites per minute.
These findings may interest health professionals who could encourage children to slow their eating speed, to play a role in reducing their risk of becoming overweight.
It is estimated that currently more than 13,000 cases of cancer in the UK could be avoided each year if everyone maintained a healthy body weight.
Research has shown that obesity increases the risk of breast cancer, bowel cancer, womb cancer, kidney cancer and food pipe cancer. Obesity has also been linked to increased risk of other cancers including gallbladder cancer, liver cancer, ovarian cancer and cancer of the pancreas, but more research is needed to confirm this.
Lead author, Professor Jane Wardle, said: "This twin study suggests that children who eat faster inherit this trait and that it is a worrying risk factor for weight gain, which could potentially be modified in childhood.
"If eating rate can be modified, and if it results in consumption of less food, then early promotion of slower eating for all children could lower the average population weight and help to control current obesity trends."
Sara Hiom, Cancer Research UK's director of health information, said: "This is interesting research that adds to our understanding of the causes of childhood obesity, an increasingly common and health threatening issue. But parents concerned about their children's weight should also consider the type of food being consumed as well as how fast their children eat it.
"Eating lots of burgers, chips and cakes more slowly will not solve the problem on its own. Children should be encouraged to eat a wide variety of vegetables and fruit while limiting the sugar, fat and salt in their diets."
An audio clip is available for download: http://media.cancerresearchuk.org/media/press/Jane_Wardle_Dec08.mp3
Clare H Llewellyn et al. Eating rate is a heritable phenotype related to weight in children. American Journal of Clinical Nutrition. Monday 8 December 2008. AJCN MS 26175.