Intermittent fasting may seem like the latest buzzworthy health fad that allegedly aids with weight loss, but experts say it's not all hype. In fact, many experts say the diet can be helpful in boosting longevity, maintaining blood sugar levels, and reaching a healthy weight.
And unlike some diet trends which can require a restricted calorie counting approach, registered dietitian Summer Yule, MS, RDN, said that that fasting does not involve cutting out specific types of foods or food groups, so it should not run the risk of nutrient deficiencies like some other eating strategies.
Although you may think that fasting simply requires skipping meals and upping your water intake, experts like Yule suggested that there are several forms of intermittent fasting that can work in almost any lifestyle.
To break down which forms of fasting do and do not work, we spoke to Yule and other nutritional experts about all the fasting methods to totally keep on your radar.
The 1:1 method is the least sustainable fasting method.
"The least successful variation of fasting is known as the 1:1 method or alternate day fasting," said board-certified cardiologist Dr. Luiza Petre, MD.
This type of intermittent fasting entails eating normally for one 24-hour period and then fasting for the next. You should be doing this once or twice a week.
Although this method is becoming popular to kick-start weight loss, she said it is the least sustainable of all fasting methods in the long term and has been associated with more overeating on non-fasting days.
The 5:2 fasting method is suitable for those looking for an easier approach to fasting.
"The 5:2 fasting method requires a person to fast for two non-consecutive days per week," Yule told INSIDER. On fasting days, she said a person consumes no more than 500 to 600 calories. A person might choose this type of fast because it is easier in the sense that they only have to be restrictive once or twice a week, she added.
Yule explained, however, that a major con to the 5:2 fasting method is that it might be very difficult to maintain over the long-term. "The person may feel fatigued, hungry, or irritable on the days that they are consuming so little food, and that could make the workday unpleasant," she said.
The 16:8 method of fasting is one of the easiest forms of intermittent fasting to maintain.
"The 16:8 method requires a person to eat for eight hours per day and to fast for 16 hours (which includes the time a person sleeps) per day," Yule said. This can be one of the easiest forms of intermittent fasting to maintain, she said, since a person can eat every day, and several meals and snacks can fit inside the eight-hour window. The person can also adjust the window to meet their lifestyle needs and behaviors, she added.
The warrior diet allows you to consume certain fruits and vegetables during the fasting period.
"With the warrior diet, a person may consume fruits, vegetables, and liquids with zero (or nearly zero) calories for 20 hours each day," Yule explained.
Those observing this diet are allowed to eat a large meal in the evening, she said. And although she suggested that this diet puts a little more focus on diet quality, she did acknowledge that it is not sustainable for many people over time.
Overall, intermittent fasting can be good for your gut.
"Intermittent fasting has been shown to increase bacterial diversity and favorably influence the balance of beneficial gut bacteria that has been shown to be protective against obesity and weight gain," said registered dietitian Christianna Moran, MS, RD, LDN.
Some think, however, that intermittent fasting has mixed findings.
"Recent studies have found that intermittent fasting has mixed findings and doesn't appear to offer superior metabolic or short term weight control advantages to traditional calorie restriction," said registered dietitian Vanessa Rissetto MS, RD, CDN.
Intermittent fasting can be difficult to maintain long-term.
No matter what method you choose, registered dietitian Chandler Ray, RD, said that intermittent fasting can be difficult to sustain long-term, especially for someone who enjoys eating every few hours.
If you do decide to try intermittent fasting, she recommended consulting with a dietitian first to get personalized guidance.
Fasting isn't always for everyone.
"Fasting is not recommended for pregnant women and for those with eating disorders," Yule said. "People who need to take medication with food may also have to adjust their window of eating to accommodate this need," she added.
Don't be discouraged to switch to a different fasting protocol.
"The most important advice is to find the method that works for you and stay on course, but don't be afraid to switch to a different protocol if you find your original choice doesn't fit your lifestyle," Dr. Petre suggested.
The benefits are worth the effort and with a little trial and error, results are sure to follow, she said.
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