The DBS surgery, attempted in the treatment of Parkinsons Disease, can also improve ones memory, Canadian researchers say.
Deep brain stimulation (DBS) involves implanting of electrodes in the brain.
The new finding means DBS can also be useful in treating Alzheimers.
A team of doctors in Canada stumbled upon a new dimension to DBS while attempting to treat a morbidly obese man. The electrical stimulation caused the patient to experience vivid memories, it is reported in the Annals of Neurology.
Lead researcher Professor Andres Lozano, of the Toronto Western Hospital, said: "This is a single case that was totally unexpected.
"We knew immediately this was important. We are sufficiently intrigued to see if this could help people with memory disorders."
The team had been trying to help a 50-year-old obese man with type 2 diabetes and sleeping disorders who had failed to respond to diet, medications and psychological help.
He had refused gastric surgery, and doctors decided deep brain stimulation, although experimental, was his best option, BBC says.
It has been found to have an impact on appetite in animal tests, but has not been widely tested as a treatment for obesity in humans.
It has been used to treat Parkinson's disease, chronic pain, severe cluster headaches and even depression with some success.
In this case into an area in the limbic system of the brain called the hypothalamus, which is thought to control the appetite.