Review: The Fast Diet

The Fast Diet claims that fasting is the surefire way of losing weight, due to our ancestors involuntarily only getting to eat most irregularly. In this review let’s look at what is up with that.

The Fast Diet In One Minute

If you ever don’t know what to do with your spare time and want to let your mischievous spirit freely roam, review diet books. Most are crap and the supply is endless. And here I go with another one.

But in order for you to not have to read through an entire text of me ridiculing a real doctor making a travesty of science, here is the Fast Diet in essence: do intermittent fasting, where five days a week you eat just about whatever you like, but the other two restrict yourself to 600 kcal.

There, I saved you money and time. Congratulate me.

Intermittent Fasting

Now, seriously, the Fast Diet (“fast” as in “fasting,” but I’m sure the double meaning was never intended) harks on the ideas of one Krista Varady, researcher at the University of Illinois, who claims to have found out that intermittent fasting is the way to go in weight loss and on the way also ensures longevity and lowers cancer risk.

This, according to Varady, is because our ancestors only had irregular access to food and our bodies have adapted to that, mainly due to a hormone called IGF-1. She and the book basically claim that intermittent fasting will lower your IGF-1 level and that is where all the goodness comes from.

The Science, Oh, The Science

Varady has done some research in the field, looking at rodents, and sure enough the effects of IGF-1 she claims to exist were there. Which is neat and nice, especially for the mice who got to live a bit longer, but it strikes me as a bit odd that most of the papers coming to the conclusion were done by her. When others took some furry-footed test subjects and went looking, they found that intermittent fasting can actually increase the level of IGF-1.

Regarding humans the research is so limited it isn’t even funny. One of the few studies here I am aware of had overweight women go through with intermittent fasting for six months, and in them the amount of IGF-1 was neither shaken nor stirred.

You catch the drift: there could be an effect, and all that is claimed about intermittent fasting might just be true, but so far the evidence is as light as your plate on one of the Fast Diet’s fast days. We need more research before anyone can claim one way or the other.

The Science Is There. Or Is It?

If that venturing into the science behind the book tired you a bit, hold on, I had to have a bit of built-up for what was to come. Because Michael Mosley, one of  the book’s authors and a medical doctor to boot, actually agrees with my criticism of the available evidence, right on page 5:

Intermittent Fasting can put us back in touch with our human selves. It is a route not only to weight loss, but also to long-term health and wellbeing. Scientists are only just beginning to discover and prove how powerful a tool it can be.

“Beginning to discover” is quite the opposite of “firmly established,” isn’t it? Then, seven pages later, we find this:

I’ve argued for years that dieting is a fool’s game, doomed to fail because of the restrictions and deprivations imposed on an otherwise happy life, but this felt immediately different. The scientific evidence was extensive and compelling, and (crucially for me) the medical community was positive.

Er, what? Does that mean that the non-existent science is compelling? And let’s not get into the “medical community was positive” part. For all we know the polled medical community consisted of Mosley’s dentist.

Hyperbole Squared

Am I too harsh with Mosley here? I don’t think so. The man is a proper, real doctor and, after all, his book claims right in the introduction to present an “evidence-based approach” to weight loss, “one that relies on science, not opinion.”

Yet not even he is sure if the science is there and to gloss over the fact he actually fills the entire book with opinion: his and his co-author Mimi Spencer’s personal, subjective, individual experiences with intermittent fasting, what it did for them and what they believe it can do for others.

Maybe gorging yourself for five days week and fasting for two is what will work for you. But you surely don’t need to buy this book to try it out.

Picture courtesy of Brett Florence.