Eating fatty junk food could destroy brain cells responsible for controlling body weight, which may explain why it's so difficult for overweight people to change their eating habits.
In a study, researchers fed rats what they described as a "typical high-fat American diet" and found they had doubled their calorie intake three days later, reports the UK's Daily Mail.
The rats also showed an inflammation in the hypothalamus, the part of the brain containing neurons that control body weight. The inflammation stopped a few days later but then recurred after four weeks.
The lead researcher said scientists also detected a healing response to brain injury called gliosis, which is "thought to be the brain equivalent of wound healing and is typically seen in conditions of neuronal injury, such as stroke and multiple sclerosis."
The researcher, Dr. Joshua Thaler of the Diabetes and Obesity Center of Excellence at the University of Washington in Seattle, added, "We speculate that the early gliosis that we saw may be a protective response that fails over time. We also detected damage to, and eventual loss of, critical weight-regulating neurons."
"The possibility that brain injury may be a consequence of the over-consumption of a typical American diet offers a new explanation for why sustained weight loss is so difficult for most obese individuals to achieve."