Obese brain may `thwart weight loss plans`
Washington: Obesity resulting from high-fat and high-sugar foods may impair brain and fuel overeating, researchers say.
According to the new research by Terry Davidson, director of American University’s Center for Behavioral Neuroscience, diets that lead to obesity may cause changes to the brains of obese people that in turn may fuel overconsumption of those same foods and make weight loss more challenging.
“It is a vicious cycle that may explain why obesity is so difficult to overcome,” Davidson said.
Davidson focuses his research on the hippocampus — the part of the brain responsible for memory and learning.
For this study, Davidson and his team trained rats given restricted access to low-fat “lab chow” on two problems — one that tested the rats’ hippocampal-dependent learning and memory abilities and one that did not.
Once the training phase completed, the rats were split into two groups - one group had unlimited access to the low-fat lab chow and another had unlimited access to high-energy food.
The high-energy food was high in saturated fat, which is considered to be the unhealthiest dietary fat as research has linked it to cardiovascular disease and certain types of cancer.
When both groups of rats were presented the problems again, the rats that became obese from the high-energy diet performed much more poorly than the non-obese rats did on the problem designed to test hippocampal-dependent learning and memory.
They tested the same as the non-obese rats on the other problem.
When the researchers later examined all of the rats’ blood-brain barriers, they found that the obese rats’ blood-brain barriers had become impaired as they allowed a much larger amount of a dye that does not freely cross the blood-brain barrier into the hippocampus than did blood-brain barriers of the non-obese rats.
Interestingly, the non-obese rats group included rats from both the low-fat lab chow group and the high-energy diet group. But this isn’t a matter of some rats having a super-high metabolism that allowed them eat to large amounts of the high-energy food and remain a reasonable weight.
“The rats without blood-brain barrier and memory impairment also ate less of the high-energy diet than did our impaired rats,” Davidson said.
“Some rats and some people have a lower preference for high-energy diets. Our results suggest that whatever allows them to eat less and keep the pounds off also helps to keep their brains cognitively healthy,” Davidson added.
The study has been published in the journal Physiology and Behavior.