Introduction
This week I thought I would take it upon myself to editorialise some of the more recent research findings on intermittent fasting. There have been many different approaches to fasting (eating less or not at all for short periods of time) suggested in scientific studies over recent years, all of which report a varying range of health benefits. Perhaps the most well-known of all of the approaches is the “5 and 2” diet of Michael Mosely fame, but there are others. And whilst there are differences in the benefits derived from each of these approaches, perhaps finding the strategy that is most feasible to us individually is of most importance initially. Some of the options are discussed below.
Article Title
‘Fasting: Starvation or Salvation’, Scott Williams, September 2016.
Background
Improved fat metabolism, greater insulin sensitivity (the opposite of diabetes), reduced body fat, improved immune function, the destruction of old and faulty cells, regeneration of new cells (even vital organ tissue such as the liver), increased growth hormone for increased repair and lean muscle tissue and improved cognitive function. These are just some of the benefits that occur when we reduce or eliminate the amount of food we eat for a short to medium time frame, known as ‘intermittent fasting’, or more indeed ‘mimicking of intermittent fasting’ (as with some you still eat, just less!). Typically these nutritional strategies will involve a day or weeks consuming only low calories such as 500 to 800 calories, compared to a typical 2000-3000 calories the average person would consume.
These strategies buck the conventional wisdom that was concerned there would be a ‘metabolic panic or protest’ from these approaches, forcing the body into ‘starvation mode’ as it lowers its basal metabolic rate in order to ensure survival. This would in turn lead to a ‘rebound effect’ with body fat increasing when eating returns to normal, commonly known as “Yo-yo dieting’.
More recent studies suggest that this only occurs after continuous complete fasting (zero calories) of 36hours or more. After this 36 hour period it is probable that there is a metabolic slow down with some of the longer fasting protocols, however this could be partly mitigated by the improvements to our physiology, listed at the beginning of this section. Permanent metabolic slowdown has also been shown when a person manages to reduce their bodyweight by 10% or more, so weight loss can definitely come at a cost.
In order to reduce the likelihood of this ‘metabolic slowdown’ the researchers for some of these protocols include quite specific menus on the low caloric days. Typically these foods would include high ratios of healthy fats, modest amounts of protein and very small amounts of carbohydrate. The carbohydrates present are very high fibre, and often included in the form of soup to provide a satiating effect.
The longer protocols (more than I day at a time) require more careful monitoring and reductions of other activities such as intense or prolonged exercise. Even though these may slow aspects of the metabolism, they may be necessary to awaken certain other metabolic pathways in order to slow or reverse the progress of certain chronic disease.
There have been published peer-reviewed studies on various formats of intermittent fasting. Below is a list of basic approaches from arguably the least extreme to the most extreme:
– Compressed eating window: Only eat between 8:30am and 6:30pm each day – normal amounts and types of food can be consumed
– Body builders cut-down diet: 18 hour non-eating window: Stop eating at 6pm the night before, do a reasonably intense workout late morning and eat a large meal at 12pm the following day
– 6 and 1 diet: The maintenance plan for the 5 & 2 diet. Eat 500 calories only per day once per week
– 5 and 2 diet: Eat 500 calories per day, 2 days per week non-consecutively
– Fasting Mimicking Diet (FMD): 5 days in a row @500 calories per day. Repeat every 3 months
– The Blood Sugar Diet: 8 weeks @ 800 calories per day.
Conclusion
We need to move beyond just thinking of the word diet = losing weight. There is now is enough quality scientific information to suggest immense health benefits from becoming a bit more structured and clever with our nutrition, with deliberate and well-timed strategies. Let’s face it, most of us will never starve and 62% of Australians are overweight or obese and it’s going to cost our economy big-time in coming years.
Unless you are directly managing a chronic disease with a specific purpose most people would be best to use the shorter easier protocols on a more regular basis. Once you have mastered this approach there is some evidence that a longer stint, perhaps up to 5 days of 500 calories in order to benefit from the deeper regenerative effects between 2 and 4 times per year. But you’ll need to pick your times to do this carefully as you need to reduce other stressors such as exercise and life stress fairly significantly.
Be very clever and selective with your food on low calorie days, include: high fluid, high fibre, high fats, a bit of protein, zero starchy carbohydrate. This also seems to be quite good for creating good nutritional habits generally, giving your digestive system a chance to repair and allowing the stomach to shrink slightly so that you know when enough eating is enough.
If you have a chronic health disease you must consult your doctor before undertaking an intermittent fasting strategy to determine which is most suitable for you. You are also advised to check the complete protocol for each version of this nutritional strategy.