What Is Intermittent Fasting and How Effective Is It?

For those tired of never-ending diet stories, 'intermittent fasting' has arrived as one of the most popular diets of recent times. Prof. Dr. Y. Birol Saygı, Head of the Gastronomy and Culinary Arts Department at Beykoz University, says: "It is known that people tend to stick more faithfully to the intermittent fasting diet. However, don't expect quick results with this diet. While intermittent fasting, people tend to lose weight quite slowly. Still, when it comes to weight loss, slow and steady is more successful in the long run."
 
In religious literature, "fasting" is known as a form of worship that does not permit eating during a certain period of time. Medical experts agree that this practice, found in many religions from Islam and Christianity to Judaism and Buddhism, contributes to human health in addition to its individual and social benefits. Today's health-conscious individuals, in search of healthy weight loss, have now drawn inspiration from the benefits of fasting to create the 'intermittent fasting diet.' 

What is the intermittent fasting diet?

Intermittent fasting restricts when or how much a person eats — sometimes both. Time-restricted eating involves eating only within a specific time window, typically eight hours, within a single day. For example, a person who eats only from 9 a.m. to 5 p.m. fasts for the remaining 16 hours. Birol Saygı notes that there are different approaches to intermittent fasting, with the most popular version being the 5:2 diet. Saygı explains this dietary approach as follows: "Alternate-day and full-day fasting don't actually involve strict fasting. Instead, you choose two or more days per week to significantly reduce your food intake, limiting yourself to just 400 to 600 calories per day. On the other days of the week, you follow your normal eating pattern. In the popular 5:2 version, you eat normally for five days and then restrict your calories on two non-consecutive days. With alternate-day fasting, you follow a calorie-restricted diet every other day."

Speak with an expert

So, can everyone try this new diet? Saygı offers the following warning: "Before trying the intermittent fasting diet, you should speak with your doctor or a nutrition specialist. Skipping meals and severely restricting calories can be dangerous for people with certain conditions such as diabetes. Some people taking medication for blood pressure or heart disease may be more susceptible to sodium, potassium, and other mineral imbalances during longer-than-normal fasting periods."
 

 Choose healthy foods

According to Saygı, some nutrition specialists are concerned that keto diets — which typically contain high amounts of meat and eggs — may put a strain on the heart. For this reason, the intermittent fasting diet should include foods rich in nutrients known to reduce the risk of heart disease, such as whole grains, nuts, legumes, fruits, and vegetables. That said, intermittent fasting diets typically do not specify which foods you should eat. Emphasizing that this concerns some nutrition specialists, Saygı says: "For example, eating hamburgers and fries five days a week and then having a single breakfast sandwich on your low-calorie day is not healthy. However, easing into changes with any diet is generally a good idea. You can start intermittent fasting by trying the 5:2 diet or time-restricted eating. Once you begin losing weight, gradually choosing healthier foods is very important."
 
Lose weight slowly but healthily

Professor Saygı, who notes that rapid weight loss should not be expected with the intermittent fasting diet, describes the positive side of the diet as follows: "People who try full or alternate-day fasting quickly become aware of how many calories are in certain foods. This helps them choose foods that are more filling but lower in calories. However, since they are not constantly counting calories, the diet is easier to sustain."

It has an evolutionary advantage

Saygı, who says that overweight or obese individuals can also try intermittent fasting, believes that this diet is compatible with the human evolutionary process. "Humans evolved in sync with the day-night cycle. Our metabolism adapted to function best during daytime eating and nighttime sleep periods. Numerous studies reveal that eating at night is closely linked to weight gain and diabetes. In fact, men who snack at midnight are known to have a higher risk of heart attack," says Saygı, going on to explain that periodic fasting triggers the fat-burning process: "Periodic fasting triggers the fat-burning process that occurs in a low-carbohydrate or keto diet. 'Keto' is short for 'ketosis,' the metabolic process that kicks in when your body runs out of glucose (the preferred energy source) and begins burning stored fat. The keto diet keeps you in ketosis for much longer because you avoid carbohydrates that supply glucose. This way, fat becomes the preferred fuel source."