In a letter to national-school principals in Dublin, Curves gym said it was "delighted to invite you, your employees and your students aged 12+ for a free tour and figure analysis".

A spokeswoman for Curves in Ireland said the invitation was a "one-off" and it was not policy to invite children to the gyms. Teenage girls were welcome to use the facilities as long as they are mature enough. "Sometimes mothers ask can they bring their daughters along, and I am talking about 16- and 17-year-olds. As long as they are healthy enough they are welcome. But it is absolutely not policy to have children in the gyms."

Gareth Leahy, manager of Jackie Skelly Fitness gym in Swords, says anyone under 16-years has to have a parent who is a member of the gym before they can take part in any programme.

Jackie Skelly's website advertises a "teen personal trainer club" for young people from 10 years of age. Leahy says this class "is about promoting fun and exercise. It's dance, and fun and games. It's about enjoying themselves and enjoying fitness. No one under the age of 16 is allowed on the gym floor. At 16 they can become members and a programme is worked out for them, depending on their ability and maturity."

Aura leisure centres, which has branches around the State, offers Khai Bo (aerobics and dance) for seven- to 13-year-olds, spinning classes for 13- to 17-year-olds, as well as other activities, such as dance and swimming programmes, for young people.

When dealing with clients under 17-years-old, neither weight nor body size is mentioned, says fitness manager Claire Costello. "There is definitely a growing market for the school-going age, with children spending so much time in front of Playstations. Everything is adapted to their ability here, from the dance aerobics to the swimming. It's about balance and healthy mind and body. It's the parents who forget about some aspects of that, though. They give them sweets and ice cream after they've been here to say 'well done'. It's not good."