GYM manager Rob Karn has warned bodybuilders in Swindon that they are putting their lives at risk by taking performance enhancing drugs like insulin.

The warning comes after an inquest into the death of former British go-karting champion Jon Daltrey, who died from an insulin overdose.

Jon, a 25-year-old fitness fanatic from Gorse Hill, had been taking insulin and the anabolic steroid nandrolone to build up muscles.

Mr Karn, who manages Trax Gym on the Station Industrial Estate in Swindon, says anabolic steroids are used by some bodybuilders in the town.

Now, he is concerned about bodybuilders using insulin. He said: "The use of steroids, like nandrolone, is more common than you would expect, but it is highly dangerous.

"Steroids are as easy to get hold of as cannabis, but they are as dangerous as taking heroin.

"They are addictive because although it might look like you have big muscles, they are full of fluid.

"If you stop taking them, your muscles just disappear.

"Insulin is not as common, but it is used by people at the more extreme end of the scale.

"If you want to build up your body you should do it by eating a proper diet and doing exercise."

Insulin is a hormone which releases sugar from the bloodstream so it can be used to create energy and is prescribed for diabetics.

Some bodybuilders use the drug before working out because it helps build muscles fast.

Like steroids, it can also be bought on the black market.

An inquest held on Wednesday heard that Jon bought phials of insulin over the internet from America, where it is sold without a prescription.

The inquest heard that Jon, who lived with his father David in Cricklade Road, Gorse Hill, started bodybuilding after his go-karting career ended.

In 1998, he won the British Go-karting Championship.

He was forced to give it up because his weight increased, and he decided to concentrate on bodybuilding, visiting the gym four or five times a week.

The coroner recorded a verdict of accidental death, and warned bodybuilders to stay away from such drugs.

Jon's father, David, called for a publicity campaign to highlight the dangers of insulin.

Mr Daltrey said: "I had no idea of the dangers of insulin, and neither did Jon. I just thought it was something taken by diabetics.

"If one good thing has come out of his death it is that the dangers have been highlighted."

The Evening Advertiser's medical expert Dr Peter Swinyard of the Phoenix Surgery in Toothill, explained how the drug affects the body. He said: "Taking insulin will stop the body from producing the hormone itself.

"This reduces the blood sugar level, which will affect just about every organ in the body.

"You would have to be bonkers to take it."