Eighteen percent of school children who took part in two health surveys carried out a year apart admitted they had eating problems with 13 percent admitting to eating problems in either the first or second survey and a further 5 percent reported problems in both surveys.

Researchers surveyed 372 students ages 15 to 17, repeating the survey after one year with the same pupils.

"For example we noticed that students who reported suffering from anxiety earlier in adolescence were 20 times more likely to have ongoing eating problems" Lea Hautala of the University of Turku, Finland, said in a statement.

"And teenagers who were dissatisfied with their appearance only had recurring eating problems if they also reported anxiety earlier in adolescence."

The study, published in the Journal of Advanced Nursing, found 70 percent of students with eating problems reported one or more health problems such as abdominal pain, dizziness, fatigue, headache and insomnia compared to 40 percent of students with no eating disorders.