Intermittent Fasting: The 5:2 Diet
Fads and trends are ubiquitous among the health and fitness industry, coming into the popular zeitgeist as quickly as they fade from the over-zealous glare of the masses. We look at intermittent fasting, a relatively recent dieting method that provides some unique benefits and may be easier to adhere to than some of the other fad diets around.
Each new 'fad', whether it's Atkins, Paleo, low-carb, Vegan, gluten free or whatever - brings with it a horde of feverishly dedicated loyalists who will (almost literally) fight to the death to defend the reputation of their chosen diet. It's like religion, but with even more fundamentalist fervour, and it's not a pretty sight.
Fortunately, there is growing awareness of a vastly simpler and more effective method of losing those unwanted pounds and improving overall health and wellbeing. The method is the intermittent fasting or starvation diet, sometimes referred to as the 5:2 diet (indicating 5 days of eating normally and 2 days of starvation, or extremely low calorie intake).
Not only that, but there is a growing body of literature to suggest that this diet might also bring with it a host of added beneficial effects such as reduced inflammation in the body, better digestive function, immune system function and the potential for a longer-lived, heathier and happier life.
What is intermittent fasting?
There are various forms of the starvation diet; taken to its logical extreme, it can be fairly accurate to its namesake, requiring the dieter to enter into a mode of, for all intents and purposes, starvation.
This involves a drastic reduction in calorie intake and can involve total fasting (excluding water) for periods of up to 24 hours at a time. However, the good news is that the more moderate version of the starvation diet, the so-called 5:2 diet, in which the dieter fasts for periods of up to 18 hours at a time, has been shown to have demonstrably similar positive effects on both weight loss and overall health.
The basic idea of the starvation diet is, as the name implies, to allocate a certain number of days each week to drastically reduce calorie intake over a given period by consuming only non-caloric liquids such as water. There are several variations of the diet; the most common approach is to select 2-3 days a week to fast for 18 hour minimum periods and only consume a maximum of 500 calories for women and 600 calories for men on fasting days.
So, for example, one might stop eating the night before an allocated fasting day at around 8.00pm, and then only consume water until 18 hours later, at 2.00pm, at which point the dieter can begin eating, so long as the 600 calorie limit is not exceeded.
What does the research say?
While there hasn't been a notable large scale study of the benefits of such a diet on the level of something like the China Study, nor have there been any definitive studies providing a clear and unquestionable link between fasting and health benefits, there have been numerous smaller studies that have revealed very likely correlations between intermittent fasting and numerous health benefits.
One such study, conducted by the Department of Nutritional Sciences and Toxicology of UC Berkeley, reviewed the effects of calorie restriction (CR) and alternate-day fasting (ADF) on both animal and human populations, with the intention of examining not only effects of ADF and CR on weight loss but also potential effects on chronic disease prevention and overall human health.
The methodology of the study was to broadly review all of the published literature to date involving animal or human studies of fasting or calorie restriction to aggregate and analyse the notion that this form of diet does contribute to risk reduction of chronic disease.
The results of the study were quite favorable in establishing a common ground of evidence that ADF and CR diets do indeed have a measurable beneficial
effect on lowering risk factors for certain diseases and helping to improve overall health. Even without the weight loss considerations (which are significant in their own right), the fact that intermittent fasting-based diets can contribute to combating chronic diseases is an important discovery in and of itself.
The measurable reduction in inflammation in the body brought on by proper adherence to a restricted calorie diet has benefits far beyond the obvious and immediate - indeed, inflammation itself has been blamed for being the precursor to a whole host of ailments and conditions for which otherwise might be considered difficult to treat and/or chronic in nature.
You might have some perfectly understandable questions relating to how an intermittent fasting based diet might affect you if you're engaged in strenuous physical activity on a regular basis, for example if you're a bodybuilder, athlete or crossfit junkie. Fortunately for you if you're considering trying this diet, the evidence points towards intermittent fasting having an overall positive effect on muscle recovery and fat loss.
A study led by Dr Krista Varady from the University of Illinois examined 32 overweight volunteers with an average age of 42 who were put on an ADF (alternate day) intermittent fasting diet for 8 weeks. At the end of the period, the volunteers had lost an average of 4kg and seen significant improvements in biomarkers related to the risks of diabetes and coronary heart disease.
Not only that, but the weight loss was primarily fat, not muscle, indicating the intermittent fasting diet may be appropriate for those even engaged in regular resistance and weight training.
So while the 5:2 diet or any of its close variants might not have the momentum of a media-fuelled hype brigade surrounding it, what's important is the evidence; and the evidence for this form of dieting far outstrips the hype. As always, however, you should do your own research and seek medical advice before embarking on any extreme diet or lifestyle change.