Most Scottish youngsters "can't see beyond the burger box" and are unaware of the "dire" long-term effects of junk food, a study has shown.

The British Heart Foundation Scotland said yesterday that 71% of children aged eight to 15 did not know that a poor diet could contribute to early death and 40% believed that the main dangers from junk food were cosmetic - spots, bad teeth and putting on weight.

One-third of children under 16 are overweight or obese and research suggests that today's generation of children may be the first to live shorter lives than their parents.

However, most children in Scotland appear oblivious to the impact obesity could have on their lives, with 57% predicting they will live to be over 80 and more than one in 10 believing they will reach 100.

Mike Knapton, the foundation's director of prevention and care, said: "Today's junk food generation can't see beyond the burger box. They are missing the fact that eating unhealthily can have dire consequences on their long-term health."

Fergus Chambers, executive director of care and services at Glasgow City Council, said the results of the study were an "extremely disappointing reflection" of attitudes. He has been charged with improving the quality of school meals in Scotland's largest city.

Mr Chambers said: "I think this is an extremely disappointing reflection. Particularly in the inner cities, children are opting to leave their secondary schools at lunchtime to eat frankly appalling food."