Obesity among people who eat a high-fat diet may involve injury to neurons, researchers at the Diabetes and Obesity Center of Excellence at the University of Washington have shown.

The researchers studied the brains of rodents for the short-term and long-term effects of eating a high-fat diet. After giving groups of 6 to 10 rats and mice a high-fat diet for periods from one day to eight months, the researchers performed detailed biochemical, imaging, and cell sorting analyses on the animals’ brains.

Within the first three days of consuming a diet that had a fat content similar to the typical American diet, rats consumed nearly double their usual daily amount of calories, the researchers said. Rats and mice fed the high-fat diet gained weight throughout the study.

The researchers found that the rodents on the high-fat diet developed inflammation in the hypothalamus, the part of the brain containing neurons that control body weight. At the same time, a group of support cells (glia) and scavenger cells (microglia) accumulated in the hypothalamus and appeared to become activated. Although this collective response to brain inflammation (gliosis) subsided days later, it recurred after four weeks.

The researchers also detected damage to, and eventual loss of, critical weight-regulating pro-opiomelanocortin (POMC) neurons.

Their work will be presented next week at The Endocrine Society’s 93rd Annual Meeting in Boston.