High-fat diet ‘injures brain’

Washington: A high-fat diet, followed for even a short time, injures the brain, a new study has found.

Researchers from the University of Washington School of Medicine looked at the brains of rodents that were bred to become obese and found that when placed on a high-fat diet.

The animals developed injuries to the hypothalamus, an area of the brain that controls the urge to eat and sends signals to stop eating when one is full.

The researchers found signs of similar damage in the same brain area in obese people.

“Within 24 hours of switching rodents to a high-fat diet, we found injury in the hypothalamus area,” Michael Schwartz, co-author of the study, said.

“We don’t know what causes the injury and we don’t know for certain that it’s a cause of obesity, but that part of the brain does control body weight,” he said.

Schwartz and his colleagues speculated that obesity might also be linked with inflammation in the hypothalamus, “which may prevent it from responding to hormones like insulin that regulate our body weight”, said co-author Joshua Thaler.

The researchers compared rats and mice that ate a high-fat diet with those that ate a regular diet over a four-week period. Within the first week, they found gliosis, an overgrowth of cells that is a sign that the brain has tried to heal itself from injury.

They also found that though the brain’s repair effort was effective, inflammation and gliosis persisted as long as the animals remained on a high-fat diet.

Moreover, the brain images of 34 healthy people, who ranged from lean to obese, revealed a link between body weight and gliosis similar to what was found in rodents.

“There seemed to be more gliosis in people who were obese than those who were lean,” Thaler said.

Since the hypothalamus is involved in our urge to eat, the findings imply that obesity, or the eating habits that lead to obesity, “caused damage to brain areas responsible for keeping our body weight stable.”

Stephen Hammes, chief endocrinologist at the University of Rochester Medical Center, who was not involved with the work, cautioned that the study was mostly done in rodents.

“We don’t know if humans respond the same way as rodents, but this study is still intriguing,” Hammes said.

He also noted that the study does not show whether the “hypothalamus caused obesity, or if the obesity caused the changes in the hypothalamus.” The findings show only a correlation.

The study has been published in the Journal of Clinical Investigation.