BODY & MIND – Intermittent fasting and exercise may have some surprising brain benefits, research shows. Forget what you’ve heard about “brain food”…turns out, the best food for your brain may be none at all. New research on intermittent fasting and exercise show some surprising brain benefits of depriving yourself of calories — at least occasionally. “We have evidence that exercise and probably intermittent fasting increase the number of mitochondria in neurons,” said Mark Mattson, a neuroscientist at the National Institute on Aging in Baltimore.
So far, Mattson and other researchers have studied the phenomenon in animals, and are beginning to understand how intermittent fasting in rats and mice can enhance learning and memory, and how it can decrease the risk of those brain functions degenerating. The upcoming human study would seek people who are at risk for cognitive impairment — obese individuals between 55 and 70 with insulin resistance who are not being treated for diabetes. They would be put through “a battery of cognitive tests,” Mattson said, while their brains were scanned by fMRI. They’d also undergo the scan in a resting state. Then, after two months with half the group on a 5-2 diet (eating a calorie-restricted diet for two non-consecutive days a week and unconstrained eating the other five days), the researchers would repeat the evaluations and compare them to the control group.
Although exercise and fasting can produce some similar results (increased production of BDNF, for example), Eric Ravussin, Associate Executive Director for Clinical Science at the Pennington Biomedical Research Center, points out that the mechanisms are very different. Still, there’s some preliminary ruminating that combining a short fast and exercise could piggyback to more quickly get the optimal results. “The thing that’s important is to dig into fat stores,” Ravussin said. “The longer the fast, the better. Or the more exercise, the better. If you could run at 6 a.m. and then skip breakfast, this would be the ideal.”
“We haven’t connected all the dots, but we know that exercise and intermittent fasting increases BDNF and that BDNF can slow resting heart rate,” Mattson said. In a review published this week in PNAS, the authors (including Ravussin and Matson) point out that an intermittent fasting type of diet has evolutionary roots — it’s likely closer to the way our ancestors ate. But if the thought of fasting makes you cringe, there’s good news: intermittent fasting can be as simple as severely restricting your calories just two days a week. Eat what you want five days of the week, and then eat 500 or so calories twice a week. Most people have better success at that model, which is popular in some fitness circles, than its precursor, alternate day fasting. –Seeker