The Problem With Fast-5
I continue to see references to Fast-5 as the most popular type of intermittent fasting, and have had people ask me why we don’t like it. To me, the worst feature of Fast-5 is that it encourages you to eat when you are not hungry. That seems a very bad lesson to learn. It is very un-natural, and must have negative consequences — though I’m not aware of it ever having been studies.
In the Fast-5 diet, you have a five hour ‘window’ during which you eat each day. If you have a large meal (i.e. supper) at the start of that time-span, you are probably just beginning to get a little appetite back five hours later. But before the five hours are up you need to eat again, knowing that you will not be able to eat for 19 more hours, so you force yourself to have another (admittedly smaller, but larger than you really want) meal.
Say you follow the exact schedule used in the book, and eat at 5:00 PM. You probably finish around 5:30 or 5:45, depending on the meal. Then, about 9:00 PM, just 3.5 hours after you finished your dinner, you think ‘Oh I better eat now, fasting starts in just another hour!’ — so you make a sandwich or other good-sized mini-meal, and eat it about 9:30, four hours after you finished dinner. You are not really hungry at all, and are just eating because it will be ‘too late’ if you wait until your appetite returns.
As I’ve stated before, that 5:00 PM to 10:00 PM eating schedule is also a poor choice, because you spend all day waiting for ‘feeding time’ and then go to sleep on a full stomach. Much better is to go to sleep just as you are getting hungry again. If your sleep hours are too late in the fast, hunger can make it hard to get to sleep, so you don’t want to go too far in that direction either. Put your sleep hours in the middle of the fast, and you will sleep away some of the most difficult hours, those when your appetite returns.
You may dream of food, but I assure you dreamed food is absolutely non-fattening. You will wake up a bit hungry, but you probably are used to that — most people are a bit hungry in the morning. That feeling will persist until the end of the fast — but it will not become a gnawing pain or severe longing, because you know it is not very long until you will eat again.
The other problem with Fast-5 is that it forces calorie restriction. That is fine if you goal is rapid weight-loss, but it is a short-term means to an end, rather than a satisfying lifestyle choice. The recommendation that you should only fast a couple days a week once you have achieved your ideal weight is not satisfactory, because it unbalances your life. Suddenly you have two days each week that you dread, because they are a break from your norm.
It is easier and more satisfying to fast 23 or 24 hours out of each 48. You are fasting less than the Fast-5 but the fasts are slightly longer, and may be more beneficial for that. I say that purely from conjecture, since nobody has studied 19 hour daily vs 23 or 24 hours of each 48 fasting. I suspect the results would be so similar that a very large study-group would be required to have any statistically meaningful results from such a study. My feeling is that the slightly longer fasts probably have slightly more beneficial effect, and that is negated by the lower frequency, so the two fasting styles even-out about the same. Give me two roughly equivalent choices, and I tend to choose the easier — and from experience Isabel and I say our 23/25 schedule is much easier than Fast-5.
