Remember This: One Great Reason to Exercise Over the Holidays
The holidays are undoubtedly the hardest time to stick to a healthy meal plan, with fatty ingredients such as butter and cream featured in many winter dishes. But keeping up with exercise during the holidays could be important for more than just your waistline, according to new research presented last month at the annual meeting of the Society for Neuroscience in New Orleans and reported recently by Gretchen Reynolds in The New York Times.
In recent years, studies on lab animals have suggested that a high-fat diet could be bad for the brain, by increasing the buildup of alzheimer's-related plaques. However, new research from scientists at the University of Minnesota and Kyoto University indicate that moderate exercise might help protect the brain from damage caused by high-fat foods.
At the University of Minnesota, scientists taught rats to move from one chamber to another when they heard a musical tone and used this to measure the animals’ ability to learn and remember.
The rats were then divided into two groups. For the next few months, the rats consumed the same amount of calories, but half ate normal food, and the others were fed a diet of at least 40 percent fat.
Four months later, the rats repeated the memory test. The half on the normal diet performed about the same as the first time, while the rats on the high-fat diet did much worse.
To measure how exercise would affect the test, half of the rats in each group were then given access to running wheels while all the animals continued on their assigned diets. Then the scientists repeated the memory test
As the scientists repeated the memory test weekly over the next seven weeks, things really got interesting.
While the cognitive abilities of rats on the high-fat diet without exercise continued to decline, the animals that ran showed notable improvements in their ability to think and remember. In fact, after seven weeks, the animals with a high-fat diet that exercised scored just as well on the memory test as they had at the start of the experiment.
The conclusion? Exercise had “reversed the high-fat diet-induced cognitive decline,” according to the study’s authors.
Even more interesting was how this study echoed the findings of researchers at Kyoto University, Japan, that were also presented at the conference.
For their research, the Japanese scientists gathered mice that were predisposed to developing a rodent version of Alzheimer’s disease. Early research showed that a high-fat diet made the mice’s condition dramatically worse, leading to full-blown dementia, while a low-fat diet and exercise slowed mental decline.
But the scientists needed clarification on whether a leaner diet or exercise was more effective in halting memory loss.
To figure it out, they fed all of the mice a high-fat diet for 10 weeks, and then divided the animals into four groups. The first group received low-fat food. The second group continued the high-fat diet but lived in cages with running wheels. The third group began a low-fat diet and exercise. The remaining mice ate a high-fat diet and didn’t exercise.
After 10 weeks, the last group had developed more brain plaques associated with Alzheimer’s disease and performed much worse on memory tests.
And while mice on the low-fat diet had fewer plaques and better memories than animals in the control group, the animals that exercised tested better than their counterparts on low-fat diets, even if they had a high-fat diet. Put simply, exercise was “more effective than diet control in preventing high-fat diet-induced Alzheimer’s disease development,” according to the authors.
While the reasons that high-fat diets affect the brain are unclear, there is one theory. Free fatty acids from high-fat foods may infilitrate the brain, said Vijayakumar Mavanji, a research scientist at the Minnesota VA Medical Center at the University of Minnesota who conducted the rat study along with his collegues Catherine M. Kotz, Dr. Charles J. Billington, and Dr. Chuan Feng Wang.
The presence of fatty acids could then jump-start a process that caused cellular damage in the parts of the brain that control memory and learning, he said, adding that exercise seems to stimulate the creation of biochemical substances that fight this process.
But while these studies are interesting, it’s important to remember that lab animals are not people, Dr. Mavanji said. Researchers can’t say for sure whether exercise would affect human brains the same way.
However, Mavanji would still recommend moderate exercise, based on accumulating evidence about the potential cognitive risks of high-fat foods. The amount of exercise required to potentially protect your brain from fatty holiday meals is relatively small, after all. The rats in Mavanji’s study ran for about the human equivalent of a 30-minute jog.