Scientists at Aberdeen University have found children who watch television have more body fat than those who do not.
According to the findings published in the American Journal of Clinical Nutrition, researchers found a "clear positive link between how much time per day children spent watching TV and how fat they were".
Study figures show 2 to 6-year-olds who spent just an hour a day longer in front of the television had on average 2 lbs (1 kg) more body fat.
Scientists believe the link is caused by children snacking on unhealthy food while watching television rather than inactivity as the process of watching TV actually stimulates eating.
Dr Diane Jackson, from the university's Rowett Institute of Nutrition and Health, said: "We investigated whether TV viewing is associated with body fatness, physical activity and calories burned.
"Using a range of techniques, including a state of the art method which measures calories burned during daily life, we measured the children's physical activity levels, their body fat and how many calories they used."
It is hoped the findings of the three-year study will be used to tackle future obesity and that reducing children's television watching could be used as a weight gain intervention.