The benefits of intermittent fasting
Intermittent fasting is an eating pattern that cycles between periods of eating and not eating (or severely restricting calorific intake). It doesn’t specify which foods should be eaten but rather when they should be eaten.
So it’s more accurately described as an eating pattern, rather than a diet in the conventional sense.
Fasting has been a practice throughout human evolution and several studies have suggested that it can have powerful effects on your body and brain and may even help you live longer.
Ancient hunter-gatherers didn’t have supermarkets or food available year-round and somethimes they just couldn’t find anything to eat at all. As a result, we have evolved to be able to function without food for extended periods of time.
There are several different methods for intermittent fasting, but they all involve splitting the day or week into periods of eating and not eating. During the fasting periods, you eat either very little or nothing at all.
Here are the most popular methods:
The 16/8 method: also called the Leangains protocol, and popularised by Martin Berkhan, involves skipping breakfast and restricting your daily eating period to 8 hours, such as 1 - 9 p.m. Then you fast for 16 hours in between. Many people find this method the easiest because they’re asleep for most of it.
The 5:2 diet: popularised by Michael Mosley, involves eating normally 5 days of the week and restricting your calorie intake to 500-600 calories per day for 2 non-consecutive days of the week.
The 20/4 method: is a variation on 16/8, but this time restricting your daily eating period to 4 hours, such as 4pm - 8pm. Twitter CEO Jack Dorsey follows something akin to this pattern, famously eating only one meal each day in the evening.
Eat-Stop-Eat: involves fasting for 24 hours, once or twice a week, for example by not eating from dinner one day until dinner the next day. There is also a variation of this method, which involves a single 36 hour fast once per week.
A 2014 review study found that intermittent fasting can cause between 3 to 8 percent weight loss over 3 - 24 weeks, which is a significant amount, compared to most weight loss studies. According to the same research, people also lost between 4 and 7 percent of their waist circumference, indicating a significant loss of harmful abdominal fat, which affects organs like the kidney, liver and heart.
Not only does fasting reduce calorific intake, but it also increases the release of the fat-burning hormone norepinephrine (also called noradrenaline), increasing metabolic rate by between 3.6 and 14 percent.
By helping you eat fewer and burn more calories, intermittent fasting causes weight loss by changing both sides of the calorie equation, as long as you don’t compensate by eating much more during the eating periods.
I used intermittent fasting myself to reduce my weight from 14 stone 7 lbs (around 92 kgs) to 10 stone 7 lbs (around 66 kgs) over a period of about 9 months. My waist circumference reduced from 36 inches to 30 over the same period.
What other affects does fasting have on the body?
The human body has evolved to survive episodic periods of starvation but there have been some studies that suggest intermittent fasting can cause muscle loss, through breakdown of muscle tissue.
Fat is stored energy and muscle is functional tissue, so muscle loss typically happens only at extremely low levels of body fat - approximately 4 percent - which is not something most people need to worry about. At this point, there is no further body fat to be used for energy so lean tissue is then consumed to keep you alive. Fat is burned first, until there is no more fat to burn.
When you fast, several things also happen on a cellular and molecular level. During fasting, your cells also initiate important repair processes including autophagy, where cells digest and remove old and dysfunctional proteins that build up inside cells.
Autophagy (ancient Greek for "self - (auto) eating (phagein)") is a cell recycling process in which cells break down damaged or unusable cell components and generate energy as a result. Damaged cell components contribute significantly to the development of age-related diseases, so the use of aged cell components in this way keeps cells fresh and healthy. Autophagy is therefore essential for the protection against diseases and can help slow the aging process.
Several other studies have highlighted a range of other benefits of intermittent fasting, including improving insulin resistance by lowering blood sugar, which should help protect against type 2 diabetes and helping heart health by reducing “bad” LDL cholesterol and blood triglycerides. It should be noted that much of this research is in its early stages.