The following post is an excerpt from a 10,000 word critique I have written and offered to the mainstream media regarding the 5:2 diet with a view to them offering a contrasting opinion, but have been declined by all.
I have been gobsmacked that this diet has not only received a "hero's welcome" by the media masses, but has not been discredited by now; I suspect it will once all the hype and euphoria have subsided and people realise that calorie restrictive diets don't work.
The Michael Mosley August 2012 Horizon programme started a significant interest in intermittent fasting and was used as a publicity platform for his up and coming book. The BBC should not be a showcase for presenter's commercial exploits in my opinion especially when the offering is fundamentally flawed on many points. Due to word constraints, we only focus here on the calorie restrictive and clinical study duration aspects.
The option that Mosley found the most tolerable was eating 'normally' for five days and eating one quarter of 'normal' calorie intake for two days. Thus the 5:2 concept was launched on the British population and a number of copycat books appeared even before Mosley's own 5:2 book was published, as "The Fast Diet" in January 2013.
Another 5:2 diet was being researched before the Horizon programme. Michelle Harvie was the lead author on a paper published in the International Journal of Obesity in May 2011.
The study concluded after 6 months, that the intermittent energy restriction group had reduced on average from 81.5kg to 75kg. The continuous energy restriction group had reduced on average from 84.4kg to 78.7kg. Both groups lost approximately 6kg on average, equating to approximately a 7% to 8% reduction from starting weight.
That's 1kg or 2lb a month, which is modest for the level of sacrifice; starving yourself two days a week and subjecting your body to a 25% reduction in calories on a weekly basis.
Despite the poor results in this clinical trial, the diet has been published in a book called "The 2 Day Diet".
The claims on the front cover of the book boasts the words "clinically proven". The "clinically proven" refers to the article in the International Journal of Obesity. Despite the fact that weight loss overall was low and there was no difference between the intermittent diet and the continuous calorie deficit diet, because this was done as a study the authors are able to make the "clinically proven" claim.
To be more accurate, the claims should have read more like, "Clinically proven to lose you an average of a couple of pounds a month over 6 months" would be more accurate or "Clinically proven to do no better than normal dieting."
Stopping at 6 months is also interesting as all the evidence from to Keys (1945) to Garner & Wooley (1991) to Franz (2007) to Weight Watchers (2010) shows regain starting at approximately 6 months after starting a calorie deficit diet; The 5:2 diet has not been clinically proven to achieve sustained weight loss, far from it in fact.
Professor Traci Mann who appeared recently on the BBC's "The Men That Made Us Thin" programme concluded as she did with her landmark research in 2007, that calorie restriction simply does not work; Her research was the most comprehensive study of weight loss ever undertaken, looking at over 100 clinical studies of diets stretching back over 30 years.
The programme's investigative journalist (Jacques Peretti) witnessed what could turn out to be a defining moment in the diet industry when he asked the former head of finance (Richard Samber) from WeightWatchers, how can an industry that is so big be based on patent failure? and Samber replied by saying that the industry relies on failure for repeat business; a damning indictment don't you think?
In conclusion, calorie restriction does not work for most people and the 5:2 diet along with other fad diets in the media this year have been driven by a marketing engine fueled by false promises, bull**** and the disingenuous make believe-science that impresses the lay man, pleases the crowds, and disgusts the one who sees right through it.
The researchers of the clinical study which was the foundation for the 5:2 diet books, either did not know a six month study and/or calorie restriction would produce inferior results or they did know and the study was created by design to legitimize their profit motive.
We will probably never know the real story!
Clark Russell is the author of the new e-book, The Fat Loss Puzzle
Follow Clark Russell on Twitter: www.twitter.com/fatlosspuzzle