Parents have been found to opt for lower calorie fast food when presented with menus stating the calorie information.
On average 102 fewer calories were chosen when compared with parents not shown the information, according to the Seattle Children's Research Institute study.
Ninety-nine parents of children aged three to six who occasionally eat in fast food restaurants were surveyed. Half the parents were provided with the calorie content of foods at McDonald's with the remainder given an ordinary menu. All were then asked what items they would select for themselves and their children.
Approximately 20 per cent fewer calories were selected for the children of parents provided with the menu displaying the calorie content. However the information was not found to affect the parents' own food choices.
Lead researcher Pooja S Tandon said: "Even modest calorie adjustments on a regular basis can avert weight gain and lead to better health over time. Just an extra 100 calories per day may equate to about 10 lbs of weight gain per year.
"Our national childhood obesity epidemic has grown right alongside our fast-food consumption. Anything we can do to help families make more positive choices could make a difference. Interestingly, by simply providing parents the caloric information they chose lower calorie items. This is encouraging and suggests parents do want to make wise food decisions for their children, but they need help."