Among the questions I get from MDA readers are those that ask about timely diet trends – you know, the latest regimens highlighted in the media or promoted by high profile stars and athletes. Some are bookstore blockbuster plans like The Zone, while others are the latest celebrity diet du jour. As my wife and – well, everyone who knows me – can tell you, I’m always up for talking, debating, deconstructing, and fully dissecting any version or concept of diet under the sun. (Thankfully, my wife at least finds it endearing after all these years.) But it’s a treat when a diet trend comes up I can actually find common ground with. Take this question from reader Jim.

Dear Mark,

I saw something this week about a “feast or famine” diet. From what I get, people alternate eating a small amount and eating as much as they want. I’m still kind of a newbie and wondered what you thought of it. Thanks! Love the PB!

The feast or famine diet (also called alternate day fasting) isn’t really a new idea (even discounting Grok’s experience), but it got recent press after the American Journal of Clinical Nutrition published results of a small study this fall. Researchers at the University of Illinois Chicago designed an alternate day regimen that restricted food on “famine” days to 25% of estimated energy needs. Sixteen obese participants went through a 10-week program: a 2-week control period, 4-week alternating day 25%/”controlled intake” period, and 4-week alternating day 25%/”self-selected intake” (albeit with diet counseling) period. The results? (Can you guess, IFers?) Subjects lost weight consistently in both 4 week periods and showed improvement in key blood markers (total cholesterol, LDL, triglycerides and systolic blood pressure).

A few years ago a neuroscientist named Mark Mattson published study results supporting the same famine-feast regimen. In commentary for The Lancet, he questioned the conventional wisdom that supported “grazing” for calories throughout the day, citing humans’ evolutionary development within an intermittent fasting existence. Mattson, a central researcher in calorie restriction and intermittent fasting, has produced research demonstrating the benefits of both practices, benefits which include enhanced memory, reduction in neurological oxidative stress (with associated risk of neurological conditions like Parkinson’s and Alzheimer’s), neuron resilience, and an improved regulation of glucose and insulin levels.

As an intermittent fasting routine, the feast-famine diet promises to upregulate metabolic systems while decreasing the overall caloric intake and oxidative stress associated with food intake and digestion. In the Primal Blueprint model, I highly recommend it. As Mattson and other researchers have noted, our systems evolved to expect periods of scarcity. We weren’t designed for the constant eating (and associated physiological stress), couched as healthy “grazing,” that we’re told to practice today. Dr. William Davis of the Heart Scan Blog, a blogroll friend of mine, did a great sequence a few weeks ago on grazing, fasting and postprandial patterns. As he emphasizes, the postprandial (aka “after eating”) period is the most damaging for artery plaque buildup. In our society, we’re encouraged to be starting the next meal before the previous one has even been fully absorbed. Our systems rarely, if ever, have the chance to return to zero. Fasting allows for that resetting.

The common criticisms of the feast or famine routine (or any form of fasting) revolve around images of all-out gorging. Apparently, too many experts believe that anyone who fasts for even 24 hours will be found in a gluttonous mountain of pizza boxes and Snickers wrappers at the end of restriction time. There are people who might go this route, but I’ll bet you a nickel they won’t continue the alternating day routine. The practice takes a certain amount of discipline, yes. But it also takes energy. Gorging yourself on the worst foods will leave you so sluggish and miserable the next day that you’ll likely drop the program. That said, if you return to a diet (say, the PB) that keeps your glucose and insulin pretty steady, you’ll feel the best benefits of the fasting routine (lightness, focus, energy) instead of the carb hangover.

Finally, I want to stress that if you’re interested in the benefits of a feast-famine routine, you don’t need to commit to an alternating day diet. Nearly any form or degree of intermittent fasting provides benefit. Do what feels manageable in the beginning. Skip breakfast one day. Reduce your calories by half for a day. Every IFer I know (myself included) developed – and advanced – their routines over time and manage it with ease now.

As always, thanks for your questions and comments, and keep ‘em coming!

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