Feeling your resolution to lose weight in the new year fading by now? A recent study might give you renewed motivation.
Researchers found that a single high-fat meal can cause changes in the brain. While the experiments were conducted in mice and rats, they also found evidence of similar brain activity in the brains of obese humans.
They fed rats and mice a high-fat diet that is typical in the United States and noticed inflammation in the hypothalamus, the area of the brain that regulates weight and hunger, within a day -- even before the rodents put on pounds.
"That was quite a shock," says lead author Dr. Michael Schwartz, a professor and director of the Diabetes and Obesity Center of Excellence at the University of Washington. "This might reflect fundamental biological changes in how the brain works that help explain why it's so hard to keep weight off."
The animals' brains began to repair and protect the damaged neurons that week, causing the inflammation to subside, but as the rodents were kept on a high-fat diet, a month later it returned and continued until the study's conclusion eight months later. Dr. Schwartz believes that when the brain attempts to heal the injured neurons, it causes gliosis, a process that results in scarring in the central nervous system.
To see if the brain reacted similarly in humans fed high-fat diets, Dr. Schwartz and his team then examined MRI scans of 34 people. Those who were obese exhibited more repair activity in the hypothalamus than people of normal weight.
I would be concerned about this. If we can see these responses occurring rapidly with eating high-fat foods in excess, maybe we as humans should think that there are potential consequences for indiscriminate eating.
In fact, Schwartz's study turned up another finding that might explain why those who have gained weight find it hard to lose it: Rodents on a high-fat diet lost about 25% of their POMC cells, which are critical to regulating appetite and staving off weight gain.
"Losing those cells would help explain why a new elevated level of body weight would occur," Dr. Schwartz told CNN.
The study was published in the Journal of Clinical Investigation. Schwartz is now studying rodents who are put on a healthy diet after weight gain to see if their brains return to normal.
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photo: The brain, with the hypothalamus in red. (Life Sciences Database/Wikimedia)