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Here's how occasional fasting could actually be good for you

Gulp.

PETER DOCKRILL
9 MAR 2016
 

To many of us who eat three square meals daily, the notion of going without food at a particular meal time – let alone skipping regular servings for a whole day – might seem like an unusual (and very likely unpleasant) approach to maintaining a diet.

But the growing popularity of fasting and intermittent fasting diets suggests that lots of people are finding something to like about sacrificing their chow. According to Mark Mattson, a neuroscientist at the US National Institute on Ageing, the toughest part is getting over the initial nil-by-mouth hurdle.

 

"Once you get used to it, it's not a big deal," he told Anahad O'Connor at The New York Times. "I'm not hungry at all in the morning, and this is other people's experience as well. It's just a matter of getting adapted to it."

Mattson practices a particular kind of fasting called time-restricted feeding, in which one consumes all of a day's calories in a small window of time – perhaps 6 to 8 hours in total – and not eating any food outside that set period. In his case, he eats about 2,000 calories during the afternoon, after a run.

While that relatively extreme regimen might sound bizarre, another more popular form of intermittent fasting has been almost unavoidable in recent years: the 5:2 diet, in which people eat normal amounts of food with no restrictions for five days of the week, then fast for the remaining two days, only eating minimal amounts, if anything.

But while the 5:2 phenomenon has been written off by many as just the latest fad diet, its proponents argue it has scientific precedent.

"From an evolutionary perspective, it's pretty clear that our ancestors did not eat three meals a day plus snacks," Mattson said. And he's likely right. Explanations for when the three square meals custom originated differ, but it's clear it's a relatively recent human invention. Some say it began in medieval times, while others claim it came about during the Industrial Revolution.

But just because three square meals (plus those occasional ever-present snacks, or course) might be what most of us eat – and yes, it can be a healthy format to follow – doesn't mean that it's the only way to consume our energy requirements, nor necessarily the healthiest.

Mattson developed his own interest in intermittent fasting after reading about studies on alternate-day fasting in mice, which showed the regimen helped protect the animals from strokes, Alzheimer's disease, and Parkinson's, in addition to boosting their lifespans by up to 30 percent.

He went on to conduct his own study on the 5:2 diet in people, which showed that a group of participants who intermittently fasted lost more weight than a control group restricted only to a low-calorie diet. The fasters also retained more muscle and showed improvements in blood sugar regulation.

Another study found that obese adults who engaged in alternate-day fasting lost weight in addition to showing significant reductions in cholesterol, blood pressure, triglycerides, and insulin. One factor that affected the experiments, however, was a sharp dropout rate – with up to 20 percent of participants unable to cope with the rigours of only eating every other day.

Aside from the potential health benefits of fasting – more of which may (or may not) become known as further studies of these kinds are carried out – at least one of the advantages of the intermittent approach is how simple it makes the act of restricting what you eat (at least for five days of the week in the 5:2 diet).

"Most people who do this understand that it's not about binge eating," dietitian Joy Dubost from the Academy of Nutrition and Dietetics told The New York Times. "But they like that it gives them the freedom not to worry about calories, carbs and other restrictions on days when they're not fasting."

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