You’ve probably heard of people doing ‘intermittent fasting’.
Some follow the popular 5:2 diet, while others might only eat within a specific window of the day.
Regardless of the method, essentially it all comes down to timing when you eat and monitoring calorie intake within those times.
What is intermittent fasting?
“Intermittent fasting is a general term used to describe a variety of approaches that change the normal timing of eating throughout a day, with short-term fasts used to improve overall health,” Dietitian Robbie Clark told Mamamia.
“In other words, the one consistent theme of intermittent fasting is that individuals periodically fast for a longer duration than the typical overnight fast that occurs while you sleep.”
The overall health benefits Clark refers to go way beyond weight loss (more on those later) but of course fat loss can be a result for those who are overweight. First, let’s take a little science lesson in what happens when we eat.
“When we eat, we ingest more food energy than our body can immediately use. As a result, this energy is stored away for later use,” Clark said.
“Enter the hormone, insulin. Insulin is the key hormone involved in the storage of food energy. To put it simply, insulin rises when we eat, helping to store the excess energy, known as glycogen, in the liver. There is, however, limited storage space, and once that is reached, the liver starts to turn the excess glucose into fat.”
Through fasting the process is essentially reversed, whereby the body calls on the excess energy stored as fat to use as the energy it needs to function.
“When we fast, insulin levels fall, signalling the body to start burning stored energy, since no mfore is coming through food. Blood glucose also falls, so the body must now pull glucose out of storage to burn for energy,” Clark said.
Intermittent fasting, also referred to as periodic fasting, works on the stop-start premise so as not to slow the metabolism down in a detrimental way, which can occur with long, extended periods of not eating.
How is intermittent fasting done?
There are a few different approaches to intermittent fasting. Below, Clark outlines some of different types:
The 5:2 Diet
This is one of the most popular intermittent fasting plans. The diet allows you to follow a ‘normal’ healthy pattern of eating for five days followed by two ‘fasting’ days. On fasting days, energy intake is restricted to around 500 calories for women and 600 calories for men, per day.
Fasting days can be consecutive or split over the week. The daily calorie allowance can be eaten over various combinations of one, two, or three meals plus snacks, depending on personal and practical preferences.
There are also variations of the 5:2 Diet, including 6:1 (restricting only one day per week), 4:3 (restricting three days per week) or ADF (alternate day fasting).
This method recommends you fast for 16 hours a day and limit your eating to an eight-hour window. Most often, this simply involves skipping breakfast and eat between the hours of 12-8pm.