It is said dieting can often depend on mind over matter.

But for a Sutton hypnotherapist, who claims he can perform gastric band hypnosis, that really is the case.

John Mill, 46, has been running group hypnotherapy courses at the the Thomas Wall Centre where he claims he can convince his patients they have had gastric band surgery.

The former childline councillor said: “I put them into a deep trance, and I take them through the medical procedure, from a consultation, and in to the hospital and in to the operating theatre.”

He said it made patients feel they had had the surgery, where stomach size is dramatically reduced.

The operation costs £8,000 and Mr Mill offers group sessions for as low as £10 each.

He said most people who see him are ready for “the op” after nine sessions, after he has explored his patient’s relationship with food to get “lasting results”.

Mr Mill claims he has had some excellent results, with 95 per cent of his patients eating less.

One patient, Michael Schiniou, 49, said the treatment has seen him lose four stone in three months.

The binge-eating DJ, who has struggled all his life to lose weight, dropped from 20-and-a-half stone to 16-and-a-half stone, and is confident of losing a further three stone.

Mr Schiniou said: “Its hard to explain what has happened to me really. I know I haven’t had the surgery, but I think in my subconscious I think I have.... Whatever he has done to me it has worked.

I’ve got a new attitude towards eating.”

He also said he remembered the operation as if it happened, and felt a tightening in his stomach afterwards.

The DJ and producer, who performs under the name Jazzy M, and used to have a residency at Ministry of Sound and Pacha in Ibiza, said: “I remember smelling the disinfectant in the operating theatre.”