The eating disorder called Bulimia Nervosa (characterized by recurrent binge-and-purge behavior) makes sufferers more impulsive than their peers.
The illness, which came to prominence when late Princess Diana admitted that she had been a sufferer, often affects people in their teenage years or early adulthood.
In the study, researchers found that bulimics are less able to control their urges and more likely to act on instinct than non-sufferers.
During the research, boffins found that during psychological tests sufferers reacted more impulsively than non-sufferers.
When they were asked to give an answer to a simple test they were more likely to plump for an answer more quickly, even when it could be wrong, the study revealed.
Also, brain scans showed different responses in the part of the mind that regulates behaviour, reports the Telegraph.
"Patients with bulimia exhibited greater impulsivity than (non-sufferers), responding faster and making more errors," according to the findings, published in the Archives of General Psychiatry journal.
Even immediately after they had got one of the questions wrong they would still go on to make another unforced error for the same reasons, the study found.
To reach the conclusion, researchers from Columbia University in New York and the New York State Psychiatric Institute tested 40 women, half of whom had the condition and half who did not.