Fasting Twice A Week Might Boost Brain Health, But It’s Still Not A Smart Idea
Scientists are reporting that fasting one or two days a week can boost your brain health and increase longevity. While that sounds like a good recipe for an eating disorder, there are better ways to make sure your diet is good for the brain and body than starving yourself every few days.
The study comes from the National Institute on Ageing, where researchers looked at whether intermittent fasting—eating no more than 500 calories per day, one or two days per week—could help protect the brain against Alzheimer's, Parkinson's and other degenerative diseases. The results in both animals and humans so far have been promising.
That's not surprising. Earlier this month, Mayo Clinic researchers reported that overeating can double the risk of memory loss in older adults. There's increasing evidence of links between obesity, diabetes and dementia, and that things like trans fats can cause brain shrinkage. Conversely, the effects of a low-calorie diet on longevity and brain health are well known. Rats and mice on calorie-restricted diets have increased their lifespan by up to 40%. And calorie restriction—known as CR among devotees and researchers—has gained an intense human following and spawned popular books like The Longevity Diet.
But consistently keeping caloric intake low is something not a lot of people have the desire or willpower to do—which is why NIA researchers want to see whether regular, short-term bursts of CR could have the same effect. Or maybe it could work even better. Mark Mattson, head of the NIA's neuroscience laboratory, thinks overall calorie restriction “is not likely to be the best method of triggering” brain protection.
“It is likely to be better to go on intermittent bouts of fasting, in which you eat hardly anything at all, and then have periods when you eat as much as you want,” he said. “In other words, timing appears to be a crucial element to this process.”
Mattson also said intermittent fasting would be easier for people—knowing that after a day with little or no food they could eat as much as they wanted the next day—than cutting back on calories overall. Really? Twice-weekly fasting seems like a less tenable plan than overall CR to me. People following a calorie restricted diet (1,200-1,400 calories per day) all the time get used to it. Their bodies get used to needing less calories. They figure out ways to still get all the nutrients they need while eating less food, ways to cook, eat and feel full that are nutritious but low-calorie.
In order to do calorie restriction successfully and healthily, it takes a total dietary overhaul—the kind which you can't learn fasting twice a week and then eating as much as and whatever you want the rest of the time. If your body doesn't get used to an overall decrease in caloric intake, aren't you likely to compensate for the fasting days by eating more/worse on non-fasting days? And to feel incredibly hungry and grumpy when you do fast? Maybe I just don't get it (I'm no neuroscientist), but it doesn't seem like something that would work well for many people outside a laboratory setting.
It does, however, seem like a recipe for creating disordered eaters. Starve yourself twice a week, eat as much as you want other times? That's sure to inspire a really healthy relationship with food.
As the UK Alzheimer's Society told the Huffington Post: “The best way to cut down your chances of developing dementia is to combine a balanced diet with regular exercise, not smoking, and getting your blood pressure and cholesterol regularly checked.”
I think all the research on the interplay of diet, brain health and longevity is fascinating (and important). I may even become a total CR nut someday. But this periodic fasting scheme just seems dangerous and silly. It's exactly the kind of magic bullet approach we love—do this one straightforward thing and then you can keep doing everything else the same and still lose weight/stay healthy/not die!
Eating for health requires an overall commitment. The upside is that cutting back on processed foods and eating a diet high in Omega-3's, fruits, vegetables and whole grains can also boost or extend your brain's health—and you don't have to live like an ascetic or a bulimic teenager to do it.