Lynsey did a lot of exercise in her bedroom so her parents wouldn't know, but many sufferers burn their calories at the gym.
Susan Ringwood is from beat and says staff at health centres should be trained to spot and advise compulsive exercisers.
She told Newsbeat: "We would like to see the exercise industry and the gyms in particular have some guidelines in place to help people who might be at risk."
Gym owner Mario is not convinced that fitness centres can help
The charity also wants gyms to take a record of people who might have a history of eating disorders.
"If you've got a heart complaint or asthma it's marked in your notes when you join. We'd like the gyms to do the same with eating disorders."
Doing too much exercise puts a dangerous amount of pressure on your body.
Muscles and bones are often damaged and if they're not given time to heal it can result in long-term damage, like osteoporosis, arthritis and heart problems.
Not everyone thinks health clubs should be made to help sufferers though.
Mario Pederzolli runs Fitrooms in south London. He said: "A member in a gym working out - that's only a very small part of their week.
"Who's to say what they'll be doing elsewhere? At the end of the day it's about the individual rather than a nanny state blanket rule for everybody."
At the moment there are no guidelines for dealing with compulsive exercisers but the Fitness Industry Association, which represents around half the UK's gyms, says staff can and should act if members are making themselves ill through exercise.
Doctors say teenagers and young people especially should try and limit gyms sessions to three to four 45 minute sessions a week.
Anyone who is worried about over-exercising is advised to speak to their GP.