The earlier a woman starts to diet, the more prone she will be to health problems such as eating disorders and alcohol misuse, scientists have warned.

A study at Florida State University followed 1,340 students for 10 years and found cultural pressures to stay thin affect women of all ages. Some began to watch their weight and actively diet at the age of three, while others started to follow a calorie-controlled programme at the age of 26. Researchers noted the earlier a woman started to diet, the more likely they were to suffer long-term health consquences.

Psychology professor Pamela Keel, who led the team, said: 'Younger age of dieting predicts greater problems 10 years out from college.'

She said it is not completely clear why dieting at an early age may have such an effect on health later in life. One possible reason was 'there is already something different' about women who start dieting at an early age in terms of their social environment or genetic make-up.

Eating disorders are often driven by social, psychological and biological factors, said Professor Keel. She said discouraging weight loss diets in young girls may reduce risk for eating, alcohol and weight-related problems in adulthood.