“CAVEMAN FASTING DIET MAY LEAVE WOMEN DIABETIC” says an article published in the Daily Express on 29th January 2013!
This of course relates to the 5:2 fasting fad, where dieters are told they should seriously restrict calories for 2 days a week and then enjoy whatever they like for the other 5 days. In November 2012, The New Scientist Magazine raised some concerns about this diet, so maybe it should come as no surprise that some are now reporting adverse effects from this latest craze. The New Scientist pointed out that the research behind the fasting diet was undertaken on rats and mice – for whom it worked well. BUT it didn’t work in research involving primates – humans are of course top of the primate tree. So I guess the question that might reasonably posed to fans of the 5:2 fasting approach is “Are you man or mouse?”
The point raised in the Express report is that while the diet seems to work for men, women are potentially risking serious health issues, including diabetes. And it all comes down to one of the fundamental tenets of my favoured nutritional approach: body composition! The article explains the dilemma as follows:
Men have a higher percentage of muscle, which gives them a faster metabolism than women. This is because muscle actively burns calories, while body fat is a store of calories. If a man and woman of comparable size, therefore, restrict their dietary intake to 800 calories a day, the man will inevitably lose more weight than the woman.
The fact that men generally carry more muscle mass than women also seems to protect them from some of the downsides of the diet. This is explained as follows:
The average adult turns over 300 grams of protein a day. Eighty per cent of that is recycled, broken down and reused; a bit like Lego bricks. After after a certain period of time these proteins become worn out, can no longer be used again in the body’s natural recycling processes, and are effectively lost to the body. What we cannot salvage, we need to replace. That replacement must come via the diet.
Protein is non-negotiable, and unlike other micronutrients you need it every day. What this means is that the body has no way to store excess amino acids – the building blocks of proteins – so essentially we need to consume a range of amino acids every day to provide the body with these essential “Lego bricks”. If the amino acids are not available from the diet then the body begins to sacrifice its own muscle to release the necessary proteins and amino acids for the purposes of this recycling process.
Of course, once you start skipping meals you will compromise your intake. Because men have a higher reserve of muscle they can call on it for protein during fasting days. Women, however, soon begin to lose too much muscle and adversely affect their body composition to a much greater degree than men.
Here we have it again – it simply isn’t true that you can eat what you want and lose weight healthily. What we eat affects our bodies in so many ways – we need nutrients based on our own unique body and lifestyle to make sure we eat all the things needed to sustain, maintain, repair our body. Any diet that fails to protect, or even promote, your body composition is quite simply flawed – it may lead to weight loss, but there’s every chance that you are sacrificing healthy lean tissues and holding on to body fat.