Curious about intermittent fasting? Here’s what experts say you should know

Intermittent fasting (IF) isn’t a new way of eating, but researchers and experts say it’s an area with potential.

It’s important to know that research on intermittent fasting is “still in its infancy,” said Amy Kirkham, assistant professor in the department of cardiovascular health at the University of Toronto. She has also led several studies on time-restricted eating, which is a form of IF.

Intermittent fasting is generally defined as a cycle of eating and then fasting.

The duration of the fast can vary depending on the person or approach.

“The idea isn’t deprivation or overeating, but to balance nutrition and fasting because both are so essential to us,” Dr. Jason Fung, a nephrologist and author of several books on IF, told CBC. dose Guest host Dr. Peter Lane.

says Anar Aledina, a registered dietitian in Richmond Hill, Ont. Intermittent fasting is a “reset” for our bodies. And she adds that stopping eating prompts our bodies to cleanse themselves and get rid of more old cells.

Fong and others say there is some promising research showing health benefits of IF, such as improved cardiovascular health.

Research has shown that many of the health benefits of fasting usually appear between 14 to 16 hours, says Aledina.

Studies have shown that during this time you are fasting, [it] It can have really important markers in your metabolic health, for example with cholesterol, blood sugar and inflammation. So it can really help bring those levels down.”

But before you consider fasting, Aledina and Fung stress that fasting isn’t for everyone.

So if you’re interested, here’s what experts say you should know about intermittent fasting.

Is it safe?

For most people, it’s perfectly safe to stop eating for periods of time, says Aledina.

“Giving your body that break is totally fine and it’s actually good for you,” she said.

Those who do not try intermittent fasting are:

• Anyone with a history of eating disorders.
• Anyone who is underweight or malnourished.
• pregnant women.
• lactating women.
• children.

Allidina and Fung recommend speaking with your healthcare provider before trying intermittent fasting.

Is there one method for intermittent fasting?

There are several different methods of intermittent fasting.

Time-restricted eating (TRE) is a popular method because it limits when you eat your meals and snacks to a specific period of time.

The most common fasting strategy, Fong says, is 16 hours of fasting and eating within an eight-hour time period.

He said, “So you can eat from say 11am to 7pm or you can eat early, say from 9am to 4pm. There are different ways to do it, but this is one of the most popular times.”

Another method is the 5:2 method, where you eat normally for five days and then restrict calories two days per week to about 500 calories per day for women and 600 calories for men.

Alternate day fasting, or ADF, is when someone eats food during an eight-hour period and then doesn’t eat the next day, which translates to roughly 36 hours of fasting.

Fong adds that there is flexibility with intermittent fasting.

“There are pros and cons to all of these strategies,” he said. “So it’s not like one is right and one is wrong. It’s really finding what works for you.”

Are there health benefits?

Yes, but it depends on the length of the fast and the fast.

Anecdotally, Fong and Aledina have heard from people who have tried intermittent fasting that they feel more alert, energized, and less tired.

Research on other health benefits is varied.

University of Illinois researchers who published a review of clinical trials found that the three main types of intermittent fasting — TRE, the 5:2 diet, and ADF — can cause “mild to moderate weight loss” in those who are overweight and obese.

They said that mild to moderate weight loss was a change of about 1 to 8 percent from baseline. But they said the ADF and the 5:2 diet are “the only fasting approach that results in clinically significant weight loss,” according to published their review In the peer-reviewed Journal of Nutrition Annual Review in 2021.

They went on to say that these regimens “may also improve” some aspects of cardiovascular health such as blood pressure.

Korean researchers who published Systematic review and meta-analysis In a 2020 peer-reviewed journal Nutrients, I found that time-restricted eating can help some shed a few pounds and improve cardiovascular health.

Fong says people may lose weight while fasting because the body uses two different types of energy: sugar and fat.

When the body runs out of glucose (the main type of sugar in the blood), it turns to fat stores, a process known as a metabolic shift.

However, there is research — including a study published a week ago in the Journal of the American Heart Association — that suggests that intermittent fasting methods may not be better for weight loss than caloric restriction.

to study Published in the New England Journal of Medicine Last year showed that among 139 obese participants, time-restricted eating with restricted calories “was no more beneficial” than daily calorie restriction.

Other researchers who led a randomized clinical trial Results published in 2020 found that time-restricted eating did not show significantly different benefits for weight loss or cardio metabolism compared to a control group.

in another place A study published in 2017 in the peer-reviewed JAMAHowever, researchers did not find a better alternate day fasting for weight loss or maintenance compared to daily caloric restrictions.

Kirkham says more studies on intermittent fasting are needed.

“We definitely need more research to fully understand all the different parameters and their potential health effects and certainly their safety within specific populations,” said Kirkham, who recently received funding from the Canadian Diabetes Foundation for research on the impact of the intermittent fasting period on blood better. sugarcontrol.

More research is needed on the intermittent fasting approach, especially in terms of long-term effects, according to several researchers who have published studies.

If I want to give it a try, how can I get started?

Before anyone starts intermittent fasting, Aledina suggests people make sure their diet is full of essential nutrients.

“Once that’s done, you can slowly introduce intermittent fasting, starting with 12-hour fasts and building up to 14 to 15 to see how that feels,” she said.

Fasting doesn’t have to happen every day at first, she adds, as it will take time to fit it into your schedule.

Kirkham says there are also free apps that can help people keep track of their intermittent fasting.

She adds that most people adjust to a changing eating schedule after the first week. When starting out, it is important to remember that minor symptoms such as headache, feeling hungry or irritable are common.

“It may come as a shock to the system at first, but I think if you give it a try for two weeks … and if you don’t feel better, you may have got your answer,” Kirkham said.

“Like any health intervention, it is not a one-size-fits-all.”