Putting Alternate-Day Intermittent Fasting to the Test 

Does strict, day-to-day caloric restriction lead to slowed metabolism during weight loss or does fasting every other day offer better compliance and results? These are examples of intermittent fasting regimens that could have been a natural part of our ancestors’ diets for centuries.
Intermittent fasting is viewed as a way to stress the body in a positive way, mirroring the concept of hormesis in biology where “what doesn’t kill you makes you stronger.” However, despite its root in legitimate science, the intermittent fasting craze might have been exaggerated, and its risks downplayed putting science behind marketing.
Although religious fasting, such as Ramadan or Yom Kippur, has been studied widely, alternate-day fasting, where eating is done every other day, has also gained attention. The hope is that alternate-day fasting helps one to experience certain benefits of taking a break from eating without the risks of prolonged fasting. Though it is important to note that fasting every other day may become difficult for some individuals.
It is reported that mice that are fasted every other day don’t lose weight. Instead, they just eat about twice the amount of food in one feast on their fasting day. However, humans don’t react the same way. A study that involved lean men and women found that fasting for 36 hours led to an average increase of 20% in calorie intake post-fasting, leaving fasters with a large calorie deficit.
Research indicates that some individuals appear to eat less or nothing at all on the day after a day-long mini-fast. Participants in an eight-week study reported feeling very little hunger after being restricted to about 500 calories every other day. This approach helped them lose an average of about a dozen pounds during the study period. A similar study with a control group found that the weight-loss outcome did not change when individuals were prescribed 500 calories on their fasting days whether it was divided up throughout the day or in a single meal.
Finally, a study found that participants lost an average of 13 pounds and two inches off their waist by feasting on unlimited above-ground vegetables on fasting days rather than being restricted to a set number of calories.
Overall, studies show that alternate-day fasting regimens result in a significant reduction in body fat and have shown about a 4% to 8% drop in body weight after 3 to 12 weeks.