What is intermittent fasting?
Intermittent fasting is an eating plan that switches between fasting and eating on a regular schedule. While traditional diets specify what you should eat, intermittent fasting focuses on when you should eat instead. This may mean fasting for a certain number of hours each day.
“There are many variations of intermittent fasting but in each version food intake is restricted for a period of time and then you can eat in a non-restricted way for the remaining period of time,” says Chloe Hall, dietitian and spokesperson for the British Dietetic Association.
A popular version of intermittent fasting is the 5:2 diet. Dieters are recommended to consume a normal number of calories for five days a week (about 2,000 for women and 2,500 for men), but to eat just 25% of their usual calorie intake for two, non-consecutive days. This is around 500 calories for women and 600 for men. Crucially, there are no restrictions on the types of food you can eat.
Another regime, called the 16/8 method, involves restricting your eating to an eight-hour period before fasting for the 16 hours in between.
What are the benefits of intermittent fasting?
Fasting has long been associated with religious rituals, and some researchers argue that our bodies have evolved to be able to go without food for many hours or even days. When humans were hunter gatherers, going for long periods without eating was common.
In recent years, however, intermittent fasting has become a popular way to manage weight. Today, there is a growing body of evidence suggesting that specific types of intermittent fasting diets may be beneficial for certain people, including those with obesity and those at high risk of developing type 2 diabetes.
After hours without food, the body uses up its sugar stores and begins to start burning fat. This is sometimes referred to as metabolic switching. Intermittent fasting extends the period when your body has burned through the calories consumed during your last meal and begins spending fat.
“Some studies have shown that as well as weight loss, intermittent fasting may help improve cholesterol levels,” says Hall.
One study found that intermittent fasting increased insulin sensitivity and reduced obesity. A separate 2019 paper found that eating during a six-hour period and fasting for 18 hours can trigger a metabolic switch. This resulted in …….