A recent New York Times article describes a book that was released in Britain earlier this year and has started a new dieting craze in that part of the world. Titled “The Fast Diet”, this book describes a dieting plan that uses the idea of intermittent fasting: eating whatever you want (within reason) for 5 days of the week, then only eating two tiny meals a day during the other two. Co-author of the book Dr. Michael Mosley describes how, by following this regimen, he: lost 20 lbs., reduced his blood glucose and cholesterol levels, and reduced his body fat percentage. Many others have also claimed to have similar results, and this brings up the question of: why does this diet work so well?
Mosley mentions that the earliest ancestors of humans lived a feast-or-famine existence, gorging themselves when they had the chance and then going without until they were able to find another source of nourishment. The Fast Diet therefore is simply a return to our evolutionary roots, to the lifestyle that humans were adapted to prior to the introduction of agriculture. Additional support for this idea can be found in the fact that in times when the body does not have food to store, it turns its energies toward repair and recovery. If food came only periodically, then it makes sense that natural selection would favor individuals who put obtaining nutrients from food and storing them as a higher priority than performing comparatively insignificant repairs that could wait until later.
This idea of returning to our evolutionary roots is certainly an interesting idea, and Mosley and co. have demonstrated that their way has the potential to help improve human health in our modern society. However, there are also many other factors that play a role in how our diet affects our health. For instance, agriculture not only provided a more constant food supply but also changed the composition of what we eat. Our sugar and cholesterol rich diets have just as much, if not more, of a say in how much of how our diet affects us as the intervals in which we eat. So while The Fast Diet might be a step in the right direction, it should also be noted that there are many other factors that need to be accounted for in forming a healthy diet as well.