Parents should be advised against feeding their children "diet" versions of high calorie foods, say experts.
A study in young lean and obese rats has found that substituting low calorie versions foods caused all to overeat.
It is thought that low calorie versions of conventionally high calorie foods may disrupt children's ability to determine calorific content through taste, leading them to overeat as they grow up.
"The use of diet foods and drinks from an early age into adulthood may induce overeating and gradual weight gain through the taste conditioning process," says lead study author Dr David Pierce at the University of Alberta, USA.
"Based on what we've learned, it is better for children to eat healthy, well-balanced diets with sufficient calories for their daily activities rather than low-calorie snacks or meals."
He adds: "Parents and health professionals should be made aware of this and know that the old-fashioned ways to keep children fit and healthy – ensuring they eat well-balanced meals and exercise regularly are the best ways.
"Diet foods are probably not a good idea for growing youngsters."