TV presenter endures tapeworm experiment

The parasites were for many years thought to be a weight-loss aid to past generations, with Victorian women swallowing their eggs to get thinner.

But Mosley found he actually gained around 2lb during his stint as a human guinea pig for a BBC4 programme to be screened next month.

He has also revealed that health and safety regulations meant the BBC cleared him to consume the tapeworms - which can grow up to 100ft in length in the intestines - but drew the line at him deliberately getting head lice, even though it affects millions of schoolchildren each year.

Mosley - who has made a number of films about diet and exercise among his documentaries - examines the effects in a film called Michael Mosley: Infested! to be screened next month as part of the channel’s Natural History season.

He said his weight gain could have been caused by the need to increase his intake as a result of the parasites living in his guts.

“I was keeping a food diary to see if my food preferences changed. I think I probably ate a bit more chocolate. Tapeworms like beer and chocolate - they like carbohydrates. My weight if anything went up a bit. One of the theories is that the tapeworm probably encourages you to eat more. You feed it.”

Mosley tracked down the tapeworm at an abattoir in Nairobi in Kenya and ate cysts from the tongue of an infected cow, cutting away the meat surrounding them to avoid any infection. In order to be sure of a good hit rate for the worms he ate three cysts, all of which developed into worms.

“It’s not something you can easily lay your hands on,” he said.

“My wife’s a GP and she was not very keen but she said it was OK because beef tapeworm is relatively innocuous. And also it is not infectious.”

The beef tapeworm makes its home in the intestine but the far more dangerous pork tapeworm moves around the body and can cause brain cysts in humans