A link between a high-fat diet and brain damage has been discovered by a team of American scientists, according to a study published in The Journal of Clinical Investigation.

The study showed that suddenly switching rodents to a diet high in fat led to inflammation in the hypothalamus, the part of the brain that controls body weight.

The hypothalamus, which regulates bodily functions such as hunger, thirst, sleep and body temperature, uses leptin to suppress appetite.

In humans, leptin is produced in white adipose tissue or "white fat".

"So you have a situation where if you have an inflammatory response in the hypothalamus you need more leptin to do the same job, and the only way to have more leptin is to have more fat," stated lead researcher Dr. Michael Schwartz, professor of medicine and director of the University of Washington's Diabetes and Obesity Centre of Excellence, according to The Australian.

The inflammation led to gliosis or brain scarring, similar to those found in stroke patients.

In a second study where MRI scans between normal weight and obese patients were compared, similar brain scarring in the hypothalamus was later discovered in obese patients.

Since the inflammation causes a disruption in the brain, the hypothalamus ends up needing more leptin to give a signal to the body to stop eating.

"It suggests that what we have seen in the mouse and rats is also occurring in the human," Schwartz told the Vancouver Sun.

Although the researchers state that they are unsure whether this is a cause or consequence of obesity, the findings may prove useful for studies in the future.

"This may help to explain why it's so hard for obese people. They can lose weight but they can't keep it off because their hypothalamus is reading them as basically weighing the right amount," he added.