Intermittent fasting: right for you or not?

Among thousands of weight-loss methods, intermittent fasting is one of the most popular diet trends, with many celebrities talking about their success with the diet. Gettyimagesbank

By Bahk Eun-ji

Among thousands of weight-loss methods, intermittent fasting is now emerging one of the most popular diet trends here, with many celebrities reporting their own successes with the method.

What is intermittent fasting?

Intermittent fasting, also known as intermittent energy, is an eating pattern with a cycle of fasting and non-fasting over a defined period. It is mainly about when you eat, not about what you eat.

The method was introduced for the first time in Korea in BBC documentary “Eat, Fast and Live Longer” in 2012, and became popular here in recent months with a documentary on SBS introducing the method at the end of last year.

There are different intermittent fasting methods, all of which split the day or week into eating and fasting periods. Two of the more popular fasting patterns for Koreans are the 5:2 and 16:8 methods.

The 5:2 method means eating normally for five days and then fasting or eating very little for two days, and then repeating the cycle. The 16:8 method means eating for 8 hours of the day and then fasting for the remaining 16 hours.

Books about intermittent fasting are displayed at Kyobo Book Centre in Gwanghwamun, central Seoul. Korea Times file

Most people already fast every day while they are sleeping, so intermittent fasting can be simpler than other slimming methods as people can do it by extending the fasting period a little longer by skipping breakfast and eating their first meal at noon. If a person's last meal is finished at 8 p.m., fasting for 16 hours until noon the next day is not that difficult.

Unlike a common dietary plan that restricts calories, intermittent fasting does not specify which food a person should eat or avoid.

How does it work?

The key point of this fast is to reduce the total amount of caloric intake by restricting eating times. It may drive weight loss by lowering levels of insulin, a hormone that allows cells to take in glucose, convert it into fat and store it for future use.

Insulin levels drop when a person is not consuming food, so during the period of fasting, it is possible that decreased insulin levels cause cells to release their stored glucose as energy. When a body repeats this process regularly with intermittent fasting, it may lead to weight loss. The fasting leads to the consumption of fewer calories overall, which also contributes to weight loss.

There is no substantial evidence for this method, but some studies support the effectiveness of this weight-loss practice. In journal “Molecular and Cellular Endocrinology,” released in 2015, researchers reviewed 40 different studies on intermittent fasting and concluded it is effective in reducing body weight.

Disadvantages

However, experts have said there are certain advantages and disadvantages of this method just like any other diet plan. Though fasting is safe for most healthy, well-nourished people, it may not be appropriate for individuals who have medical problems.

“Intermittent fasting is more like a timed approach to eating, than a simple dietary plan. It may have some benefits for your health, including weight loss, but it's not suitable for everyone,” said Cheong Nak-yong, a physician who has been running a nutrition and weight loss clinic for 12 years in Seoul.

Cheong said intermittent fasting can be hazardous especially for people with diabetes as the fast may lead to imbalance between nutrition and hormones.

“Insulin should go up in the body three times a day at regular intervals, but if a person skips a meal or has irregular eating patterns, chances of them falling into hypoglycemia are high,” Cheong said.

Although fad diets often promise dramatic short-term weight loss, most do not result in long-term success because they promote unhealthy eating habits, he said.

“It is difficult for most people to maintain any diet that drastically restricts their food choices or requires them to eat unusual food or very little food every day. Therefore, people who lose weight through such a fashionable diet usually gain back more weight than they lost,” Cheong said.

Prof. Shin Hyun-yong of Myongji Hospital said fasting is clearly effective for weight loss in the short run, but it's not the only way.

“If you control the food you eat carefully, losing three to four kilograms is not that difficult,” Shin said. “Therefore, the key point of intermittent fasting is to change your habits and stop eating too much carbohydrates and fats.”