Every Different Way To Do Intermittent Fasting Explained

Intermittent fasting is a time-based feeding protocol that cycles between periods of fasting and eating. It can be helpful for weight loss, as a 2019 study in Current Obesity Reports revealed. Other research has also shown that intermittent fasting has benefits like "increased stress resistance, increased longevity, and a decreased incidence of diseases, including cancer and obesity" (via New England Journal of Medicine).

"Time without food allows the body to reset, leading to decreased insulin, blood sugar levels, and catabolism  — the breakdown of stored energy." Nicole Grant, registered dietitian and resident dietitian for Zero Fasting, told Health Digest. It's important to keep insulin levels on the lower side; if insulin levels are too high, it can lead to organ damage, decreased natural insulin production, and even type 2 diabetes (via Healthline). "The amount of insulin circulating in our blood lowers between meals," Dr. Melanie Boehmer, outpatient dietitian at Lenox Hill Hospital in New York, explained to Health Digest. "If you think about it, it makes sense that fasting for a period may decrease the amount of insulin release."

Nevertheless, each intermittent fasting program has its pros and cons. "It's more important to look at the diet overall, including total calories, macronutrients, and the foods you are eating," Dr. Gretchen San Miguel, medical director for Medi-Weightloss Corporate, told Health Digest. Let's take a look at the different types.

All time-restricted eating can reduce overall caloric intake, which in turn, creates a calorie deficit and allows for weight loss. However, a 2021 study published in Nutrition & Diabetes has shown that the 14:10 method provides optimal weight loss, especially when a person finishes eating in the early evening and then fasts for 14 hours.

"This [14:10 method] is an easier entry point to those interested in the incorporation of a time-based feeding protocol as the 10-hour window is a bit better for people to adhere to," Dr. Melanie Boehmer, outpatient dietitian at Lenox Hill Hospital, told Health Digest. And at least one earlier study, which was published in Cell Metabolism, has shown that 14:10 plan led not only to weight loss, but "healthier body composition, lower blood pressure, and decreased levels of cardiovascular disease-promoting lipids."

Dr. Pam Taub, a cardiologist at the University of California, San Diego's School of Medicine and one of the study's authors, told NPR, "When you go into a fasting state, you start to deplete the glucose stores in your body and you start to use fat as your energy source." This process is called ketosis, and it "can lead to a good amount of weight loss," Satchidananda Panda, another study author explained.

The Warrior Diet, or the 20:4 method, is an intermittent fasting protocol developed by Ori Hofmekler and summarized in his book of the same name. This method includes eating plant-based foods and eliminating unhealthy foods. "The goal is to reduce flours and processed sugars, and replace them with fresh raw fruits and vegetables," Dr. Allen Conrad, a Pennsylvania-based chiropractor and certified strength and conditioning specialist, told Health Digest. Popularized by Hofmekler, this diet also calls for restricting your eating window to four hours, and fasting for 20 hours. "By fasting during the day, the goal is to help eliminate the dependence on processed foods that are a staple of the average American diet," said Conrad.

"In these longer fasts, mTOR [a type of protein] is also suppressed, which allows for autophagy — the process that many of the longevity benefits of fasting are attributed to," Nicole Grant, registered dietitian and resident dietitian for Zero Fasting, explained to Health Digest. Nevertheless, reducing your eating window to only four hours a day can be problematic when nutritional needs aren't factored into consideration (via Health). As with any diet, consult your doctor to see if this type of fasting is appropriate for you.

The 5:2 diet, aka The Fast Diet, has you eating "normally" for five days a week (with little thought to calorie control) then limiting calories to 500 or 600 the other two days (via WebMD). This method of intermittent fasting was made popular by Michael Mosley, a producer for the BBC and author of The Fast Diet. Those that subscribe to the protocol appreciate not feeling deprived on fasting days, as a greater amount of food is coming their way soon enough. Also, once a weight loss goal is met, an individual can reduce the fasting days from two to one. A more extreme version of the 5:2 concept is the Eat Stop Eat diet, which calls for two non-consecutive days of total abstinence from food (via Healthline).

Of course, if you overeat five days a week, you'll likely not achieve weight loss from either program. However, a 2020 study in Clinical Nutrition revealed that a 5:2 diet — described as "a high protein, moderate fat, [and] low carbohydrate diet" — is considered a safe way to lose weight. That said, if you have diabetes, this could be a harmful program to follow, as your blood sugar level might drop to dangerous levels (via Healthline). Please consult your doctor.