What is intermittent fasting? A look at its potential health benefits

Intermittent fasting is among a growing number of weight loss regimes that have risen in popularity in recent years.

The idea is to restrict your daily eating period to a window — usually eight hours — without counting your calorie consumption, and then fast the rest of the day.

Another variation is the alternate-day-fasting approach in which you restrict yourself to 500 calories every other day and then eat as much as you want the next day.

“So basically, all it’s doing is lowering our food intake and that leads to weight loss,” said Krista Varady, a professor of nutrition at the University of Illinois Chicago. She has published several studies on intermittent fasting.

If people with obesity strictly adhere to intermittent fasting, it can generally result in losing up to 50 pounds, Varady told Global News in an interview, with most of that weight loss coming from fat mass and belly fat. For others, they may not lose any weight at all.

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But there is growing research that suggests intermittent fasting not only helps people shed pounds but can also lower blood pressure and “bad” cholesterol.

It has also been shown to be a safe diet intervention for people with Type 2 diabetes.

A peer-reviewed study published in the JAMA Network Open Friday showed that time-restricted eating between noon and 8 p.m. helped Type 2 diabetes patients lose weight and lower their blood sugar levels.

In the randomized six-month clinical trial of 75 participants, those who followed the intermittent fasting regime lost roughly twice the amount of weight over that time period as the group that was reducing their calorie intake by 25 per cent.

No serious adverse events were reported, the study said, with similar occurrences of hypoglycemia (low blood sugar) and hyperglycemia (high blood sugar) in the diet and control groups.

“The main thing we’re really seeing even in people without Type 2 diabetes, is improvements in blood sugar regulation,” said Varady, who co-authored the JAMA study.

She acknowledged, however, that the study was “small and should be followed up by larger ones.”

Before getting on any diet plan, experts recommend consulting a physician to see if it’s a good fit for them and their personal lifestyle.

Because of the emphasis on timing, intermittent fasting might not necessarily suit a night shift worker as it would a person with a regular 9-5 job, said David Jenkins, a professor in the department of nutritional sciences at the University of Toronto.

“Intermittent fasting may be good for one, but not so good for another,” he said in an interview with Global News.

“It really depends on who you are and whether it suits your particular psychological approach to food.”

Also, what and how much you eat in that eight-hour window are important considerations, he said.

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Jenkins advised against going overboard on snacking and choosing more plant-based foods, which take more time to eat.

Intermittent fasting has been shown to be safe with some side effects, according to research.

The main adverse events that people without diabetes experience are headaches, mild constipation and nausea, but those tend to go away after a week or two, Varady said.

Type 2 diabetes patients should adjust their medications before starting intermittent fasting.

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Experts say more research with bigger randomized trials over a long time period is needed to better understand the effectiveness of this diet plan.

Moving forward, Varady said additional studies should look at specific population groups.

She and her colleagues are running a study on the impacts of intermittent fasting in women with polycystic ovarian syndrome, which is a common hormone disorder that affects females of childbearing age.

They will also be conducting research on people with Type 1 diabetes, Varady said.