Fast Diet

An Intriguing New Way to Reboot Your Metabolism

I had just been studying Dr. Robert Naviaux’s information on summer metabolism and winter metabolism and was fascinated by the possibility that seasonal fasting might be a viable way to improve metabolism—-meaning, losing weight, reversing a tendency to pre-diabetes, lowering blood pressure, and decreasing inflammation—-all of which are important concerns for many of our patients.

Basically, Dr. Naviaux reviews the biochemistry of metabolism and notes that for millennia, humans have had more to eat in the summer, and much less in the winter. Over time, our internal chemistry has evolved to incorporate the presence or absence of food into our basic metabolism.

To be more specific, in the summer, a time of plenty, the master fuel sensor in the cell is mTOR (mammalian target of rapamycin) which facilitates protein synthesis and growth. In winter, a time of caloric restriction when resources stored in summer and fall had to be used with greater efficiency, the master fuel sensor is AMPK (AMP activated protein kinase). More important than these acronyms is the concept that we are designed to metabolize differently in winter than summer. Basically, after pigging out in summer, our chemistry shifted in winter to support regeneration, breaking down damaged proteins and lipids and refreshing our basic building blocks of nutrients.

After centuries of living in this way, our recent life-style allows us to eat whatever we want, whenever we want it, in what is now an “endless summer” of metabolism—–so that we no longer regenerate, or take the time to rework our metabolism, and we continue the constant growth cycle of summer with no relief. It should come as no surprise that we have become a nation of overweight individuals.

So, I was contemplating the idea of incorporating some form of fasting, or eating less, into both my own health and that of my patients, when our own Mara Jennings brought to our attention the recent work of Dr. Michael Mosley, a British journalist/physician, who produced a documentary on exactly this subject. His video, “Eat, Fast and Live Longer” is easily accessed on the internet at

and worth viewing. Fascinated by it, I bought a copy of his easily read, short volume, “The FastDiet” by Dr. Michael Mosley and Mimi Spencer and the excellent “The FastDiet Cookbook” by Mimi Spencer with Dr. Sarah Schenker and devoured them both (literally).

While weight loss is certainly important here, Dr. Mosley’s main concern is that of restoring metabolism back to normal. Using his own body measurements, he was able to show profound improvement in blood sugar levels (he had been pre-diabetic) and blood pressure and cholesterol levels by doing this process of modified fasting two days a week which he calls the “5 Day-2 Day Diet.” While technically correct, the word “fasting” is intimidating for most of us, so please do not let this language prevent you from opening up to the possibility of considering this way of eating.

This is not fasting in the strict sense at all……it is actually a very modified

way of eating in which for two days a week, not sequential, you would eat

less (500 calories a day for women and 600 for men) and the other 5 days a week, you would eat whatever you like. It was designed, by Dr. Mosley, to be quite do-able. He recognized that unless a diet is fairly easily mastered and is minimally unpleasant, no one will do it. This diet can be done and my wife and I can attest to its value and do-ability.

With my interest in seasonal eating, when I learned of this diet 5 weeks ago, we jumped in with both feet, thinking that winter was just upon us and what better time to test out these ideas than now? Better yet, with Holiday Season approaching, what better test for its success than to see if we could avoid the usual 5+ pounds we put on between Thanksgiving and Christmas.

While this report is preliminary (we have only been doing this for 5 weeks now), my wife and I have both lost 5 pounds each (despite our usual Holiday eating indulgences). I measured a wide array of my own chemistry prior to setting out on this diet and plan to repeat these tests at the end of February so I can get a better handle on how well this works over the longer haul. On the modified food consumption days (I dislike the word “fasting” as it reminds me of Rosh Hashona in which no food or liquid is consumed at all) we drink lots of liquids. Breakfast consist of eggs, a pancake of oat bran and yogurt and egg white, and coffee; lunch is a salad, and dinner includes a salad, vegetables and small amount of protein. Both the book and cookbook are full of ideas that clarify what you can eat that will allow you to comply with this diet and those suggestions are much more palatable than I would have thought. While I admit to occasional feelings of hunger, they do not last, and respond to drinking a cup of miso soup (20-30 calories) or celery with humus or a glass of greens made up in our new Vitamix.

We are very impressed with these initial results and both the science and practicality of this makes me think that this may well be a way to eat (not just diet) for quite some time to come. While I am not aware of any research in this area, I suspect that during summer I will be able to do less of this modified eating so that I can get my body into synch with its more natural metabolic patterns. Dr. Mosely comments that once you have achieved your target weight once a week is adequate for maintenance.

For those of you who wish to pursue this (under medical supervision of course), please give us feedback at this site on your progress.

Happy rebooting!