Two new studies show that eating too much fatty food causes brain damage linked to obesity.
US scientists found a sudden change to a high-fat diet triggered inflammation in a key area of rodent brains responsible for regulating body weight. The inflammation produced distinctive scarring similar to that seen in stroke patients - and that brain scarring was then observed in humans who were overweight. While the research does not unequivocally prove brain damage caused by fatty food is linked to obesity, it provides strong indications for further research. More than a third of adults in the U.S. are obese and future exploration on this issue is thus necessary.
Michael Schwartz, who is the director of the University of Washington's Diabetes and Obesity Centre of Excellence said, “It would be unlikely you could injure that part of the brain and not affect the level of bodyweight, because that's what that area does...Fast foods are more likely to do this sort of damage.”
One study found that in the brains of both obese humans and obese rats, neurons around the hypothalamus were damaged by inflammation. High-fat diets have been known to promote inflammation throughout the body, but that usually takes weeks or months to appear. Changes in the brain, however, can happen fast—even within 24 hours.
The second study found that mice on a fatty diet were slow to replace old neurons in the hypothalamus, which could also hamper its function.
Most people have a natural equilibrium bodyweight, and although they can lose or gain kilos by adjusting their diet, their body will tend to return to its natural weight once those restrictions are removed. Thus, obesity is often less a problem of losing weight than of keeping it off. The brain area that regulates metabolism, the hypothalamus, relies on a hormone called leptin to measure the changes in body weight - and leptin is produced in fat. Hypothalamus is an almond-sized area of the brain helps regulate hunger and thirst, as well as sleep and body temperature.
“So you have a situation where if you have an inflammatory response in the hypothalamus you need more leptin to do the same job, and the only way to have more leptin is to have more fat,” Professor Schwartz said. The findings are published in The Journal of Clinical Investigation.