Just one session of a non-invasive brain stimulation technique can reduce core symptoms of anorexia, including the urge to restrict food intake and feeling fat, scientists say.

Researchers carried out the first randomised control trial to assess whether repetitive transcranial stimulation (rTMS), already an approved treatment for depression, is also effective in reducing symptoms of anorexia.

Up to 20% of people with anorexia die prematurely from the disorder and treatments in adults are moderately effective, with only 20-30% of people recovering from the best available talking therapies, researchers said.

"With rTMS we targeted the dorsolateral prefrontal cortex, an area of the brain thought to be involved in some of the self-regulation difficulties associated with anorexia," said Jessica McClelland from King's College London.

"This technique alters neural activity by delivering magnetic pulses to specific regions of the brain, which feels like a gentle tapping sensation on the side of the head," McClelland said.

Researchers found that one session of rTMS reduced the urge to restrict food intake, levels of feeling full and levels of feeling fat, as well as encouraging more prudent decision-making.

"Taken together, these findings suggest that brain stimulation may reduce symptoms of anorexia by improving cognitive control over compulsive features of the disorder," said McClelland.

For the study, 49 people completed food exposure and decision-making tasks, both before and after a session of either real or placebo rTMS.

Symptoms of anorexia were measured immediately prior to and following rTMS, as well as 20 minutes and 24 hours after the session.

The food exposure task sought to provoke anorexia symptoms by asking participants to watch a two-minute film of people eating appetising food, such as chocolate and crisps, while the same items were in front of them.

\They then had to rate the perceived smell, taste, appearance and urge to eat these foods.

For the decision-making task participants had to choose between a smaller, variable amount of money (0-100 Pounds) available immediately and a larger, fixed amount (100 Pounds) available after four different time points (a week, month, year or two years).

Compared to the placebo group, researchers found that participants who had real rTMS showed a tendency for more prudent decision-making - that is, they waited for larger, later rewards (delayed gratification), rather than choosing the more impulsive smaller, sooner option.

"Our preliminary findings support the potential of novel brain-directed treatments for anorexia, which are desperately needed," said Ulrike Schmidt from King's College.

The findings were published in the journal PLOS ONE.