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Metabolic Flexibility: Part 5 of the Conversation by Dr. Barry Sears - CrossFit Journal

In Nutrition, Videos

December 17, 2009

Video Article

Four magic words key to the Zone Diet: “I can do that.”

Diets can be difficult, but they can be almost unbearable when they eliminate some of the foods you enjoy most. Dr. Barry Sears explains that the Zone Diet addresses this issue with flexibility that allows people to eat specific portions of their favorite foods so long as they balance protein, fat and carbohydrate intake.

Consistently moderate caloric intake with the appropriate ratio of macronutrients will allow your body to become more efficient at making chemical energy (ATP) from both fat and carbohydrates, which in turn allows high performance. This is called metabolic flexibility.

Cutting back calories has one other added benefit:

“The only proven way to live longer is to cut back calories—not cut back nutrition, but cut back calories,” Dr. Sears says.

Some people might see it as a bit of a paradox, but reduced calories with the proper macronutrient ratio will actually produce appetite suppression, which is a sure sign that the diet is dialed in right.

Video by Again Faster.

8min 17sec

Additional reading: Fast Food by Greg Glassman, published Dec. 1, 2002.

Free Download


25 Comments on “Metabolic Flexibility: Part 5 of the Conversation”


wrote …

“The only proven way to live longer is to cut back calories—not cut back nutrition, but cut back calories,” Dr. Sears says.

Eating ice cream, cheeseburgers, and beer, regardless of their ratios will not accomplish this task. Every site on caloric restriction I've been too says that because you're consuming so few calories, every single meal needs to be as nutrient dense as possible. This does not allow for cheesesburgers, ice cream, or beer. Barry Sears seems to mention this when he says don't cut back nutrtion, just calories, and at at the same time says it's ok to eat shit on his calorie restricted diet.


wrote …

I have to agree with sears on his take on calorie restricting but can not see how that can be done with ice cream and cheeseburgers


wrote …

So if you go 4-6 hours without being hungry thats your golden spot and you are eating right.

What if you can go 18 hours without feeling hungry? Do I need to change my diet so I'm hungry in that 4-6 hour window? (not that I plan on it but I think it a fair question)


wrote …

This post takes away from any legitimacy these Barry Sears journals ever could have had. I don't care if he has a PHD,anyone who thinks that optimal health and wellness can be achieved through a diet in which one regularly consumes a double cheese burger and 5 fries is naive to say the least. What about the role of genetics here? There are plenty of professional athletes who perform at high levels of performance on fast food diets (i.e Evander Holyfield). Does that make their dietary approach applicable to the rest of the less genetically gifted population? For that matter those pro athletes eating whatever the hell they feel like could undeniably look, feel, and perform better if they implemented some high quality nutrients into their diet.


wrote …

All he's saying is that eating crappy food in the correct proportions is better than nothing, and for some people (not Crossfitters) that is all they will want to do, but it will help them.

Also, anyone how this works is you eat ~6 meals a day?


wrote …

Maybe I'm just not understanding this correctly, but what I took from the video is that once in a while you can have whatever you want as long as it's in the right proportions.

He's not saying eat cheeseburgers everyday as a staple, but if you're going to have cheeseburgers make sure that you are supplementing with the proper foods.

He says during the interview that you won't be getting much food if you eat less nutrient rich foods, and that the goal is to find the right mix of foods that keeps you from feeling hungry more than every 4-6 hours.


wrote …

It seems to me that Sears argues that the large scale effects of a diet boil down to total calories and macronutrient balance. I know 3g CHO of spinach and that of ice cream look, taste, and satiate entirely differently, but the argument is that their metabolic effect is more similar than not. He allows for flexibility in food choice so long as the first two requirements are met. He says that it's difficult to give up certain foods, e.g. bread and pasta. By allowing Zoners to WAM whatever, compliance is theoretically easier. Still, hunger should slowly nudge them towards better food choices. That is, until they absolutely must have their yogurt, completing their journey on the food quality continuum. Sears is not suggesting to WAM cheeseburgers unless you absolutely must haz cheeseburger. I think the quality vs. quantity thing is getting a bit ridiculous.

Regarding the metabolic flexibility, isn't that the normal state of things unless you eat zero fat or are in ketosis? Or are the enzyme levels precisely tuned to fat and carbohydrate intake? Is this an hourly, daily, or weekly thing, because I thought there was some merit to the whole cyclic low carb thing.


wrote …

I'm really enjoying these videos. I like the fact that Dr. Sears is a realist. He would truly love for everyone in the world to eat only the highest quality foods, but he know that is simply not a reality. So what do we do for people that refuse to give up certain "bad foods"? Can we still make positive changes in their lives and diets in some manner? The answer is yes.

Thanks for the videos!


wrote …

That is a great point brother. I would also like to mention that if all you eat is crap on "The Zone," then you are likely to be really hungry. This diet is one of those that rewards making positive and healthy food choices and reciprocally punishes poor choices. Yeah, you can eat ice cream, but you'll be hungry, why not eat some veggies instead and fill that belly up!


wrote …

I think it is kind of funny how much of a fuss this is all causing. And unless you are just flat out an idiot, you should understand that there is probably alot more than just disagreeing on diet that went into the recent firings and deaffiliations. Pat, thanks for your comment. I don't know you, but I love your realistic outlook and down to earth persective. Notice how the "Elite" athletes that competed at the games never comment on this shit. They are the ones that need to fuel their bodies for "Elite" performance and I'm pretty sure the large majority of them do take a Paleo approach with added WAM to get to that next level, I could be wrong though. I think that too much gets made of the "Elite" part of CrossFit. I can personally tell you that out of 120 or so clients that we have here, a strict Paleo diet 100% of the time is not reasonable. Is it ideal for best results in performance, yes. But 98% of our people don't want to commit to only eating things that our ancient ancestors ate. Do I try to encourage Paleo here, yes I do. We recently did a Paleo challenge for our members and the results were incredible. Not only did people lose weight and inches from their waists, but their performance levels went through the roof. Out of those 120 or so people, about 45 of them are currently college athletes, so I exclude them from my next point, which is this-of the 70 or so "average everyday people", we have maybe 5 that even care about maybe one day competing in the games. My point is that getting people to even attempt to change their diet in a small way is a big plus. If I can get them to start to be more conscious of what they are putting in their mouths, and understand how diet directly affects performance in the gym and life, I have won, and so have they. They love CrossFit for everything it offers. We have women that couldn't do anything when they first got here and now they can almost do everything. And that is all they care about. Their concern is not being labeled as an "Elite" athlete. Let the "elite" people chase "elite" performance but for us, I feel like the Zone is perfect.


Jesse Gray wrote …

While current research shows without a doubt that a CR (calorie restricted) diet increases longevity, there is no way it can possibly good for athletic performance. I have seen people on long term CR diets, most recently, I saw the test group for the humans study on CR that was featured on 60 Minutes; and the people are all incredibly skinny and frail. Do they live much longer on average? Yes, but they all look like starving Ethiopians you can support for a dollar a day. If you want to build and support muscle mass, that's no way to do it.


wrote …

Don't short-change the message. The Zone is portion control. Its about overcoming a previous lifetime of bad food choices. When I first started, I did it on pizza and beer and it still worked. As time went by, I incorporated better and better foods and I continue to see gains.

There have to be rewards with every endeavor. Could I continue the Zone without the occasional cheeseburger and ice cream? No. The trick is not to over-do it.

If its really about eating to extract the very last ounce of performance from yourself, then go for it. But don't expect that to be everyones mantra. The bottom line is your reality. No one is going to pay me to ride my bike. I have 3 kids, a full-time job, and I like pizza, ice cream, and beer. Do I stay fit enough to do well in local races, play with my kids and keep up with my job? Yep. In spades.

Enjoy staying healthy, but don't forget to enjoy life.


wrote …

Really enjoying these videos. The questions asked are great, really expanding on the zone material that is already out there.
To: Scott Martinis, I think the number of meals can vary but for example CFJ 21 recommends 5, with meals 3 and 5 being snacks ( half sized meals )

Dr. Sears big thing is about hormonal balance, so I think he's using the cheeseburger thing as an example, not recommending it for nutrition. Who even knows whats in a McDonnalds hamburger? the more I move to quality food in zone proportions the better I feel (although I am far from 100%).

Recently gave up diet coke as well, I think the artificial sweeteners were messing with me a bit.


wrote …

Thanks for the great Zone Videos. I have had unbalanced food = performance issues my whole life, these were particularly troublesome in high school athletics. One day I would be the best on the court, the next day the worst... Wish I would have known about this back then. I now am able to better balance my food and my performance has improved. I know how I feel when I don't balance and I know why I feel that way. Since starting to "Zone" (I don't measure, I attempt to balance protein and carbs by using the block tables) I have increased my vegetable intake about 4 fold. That is a great thing in and of itself, and I do feel more stable and less tired after eating, while being able to perform better in my WODs.


replied to comment from Jesse Gray

this is not always the case I know of one guy Dr gary young that does the low CR diet and in his late 50's won a few weightlifting events and was nicely build. Also the famous Dr Bob Delmonteque in his late 80's is built better then most at any age and he does the low CR diet and writes articles for muscle and fitness magazine.


wrote …

I appreciate the commentary from people all over the spectrum on this issue. One thing I am struggling with a bit is performance vs. longevity. I know that eating crap never helped anyone, and Zone and or Paleo has contributed to really impressive results. My question is whether people think eating alot of meat (20+ oz a day) is inherently taxing to the body over the very long term. The basis for this question is that the longest living cultures seem to have a few things in common, low intake of sugar / highly processed foods and low or no intake of meat. For me eating meat seems to improve my recovery and I don't personally see any harm (assuming your sourcing quality grass fed, humane yada yada...). Aside from the ethics of eating meat does anyone have any thoughts regarding the long term stress of taking in a lot of meat. In Traditional Chinese Medicine its contraindicated to eat more the 24oz (much less depending on what you read) and they often refer to people who are well built and muscularly defined later in life as depleting their qi or essential energy. To me it seems if your moving around well, your blood levels look good and your enjoying a high quality of life its all good. That said I'm interested in peoples thoughts. Thanks.


replied to comment from Martin Adler

I do not eat meat my self for longevity reasons. I found this site about vegan bodybuilding and it looks like there are many weight lifters getting great results on the vegan diet. they have a book coming out in January called "Vegan bodybuilding & fitness: the complete guild to building your body on a plant-based diet" you can find out about that book and many other facts about vegan fitness/bodybuilding at the following link for those that may not want to eat meat :


Good point Sean, there are of course exceptions but I would be very surprised if those guys followed a CR diet while trying to build muscle. There are actually lots of body builder types who use CR diets in their leaning out phase after they've put on muscle so they look all ripped up for shows/photo shoots. Building mass though, particularly muscle mass requires a lot of fuel and anyone who has ever had experience weight training will tell you that if you want to get stronger, you need to eat a lot of food.

P.S. I looked into Dr. Bob Delmonteque and while he is a very fit looking 84 year old, he does not regularly use a CR diet, only when leaning out and he also is a huge advocate of HRT or Hormone Replacement Therapy and HGH.

Dr. Gary Young was even more interesting, if you Google his naem, the first site to come up is his personal site which has a paid ranking, the first regular ranked site is from a site that reports quack/fraud Dr's and "Dr" Young has a pretty serious rap sheet. I would seriously question any advice coming from him. He appears to be at best some kind of new age snake oil salesman who has been run out of several states and even Mexico for perpetrating medical fraud.
Link to Dr. Young


wrote …

Sean + Jesse,
Thanks for the input. I know that site well. Back in college I was super into rock climbing and spent some time on a vegan diet during which my climbing improved dramatically as I leaned but then I found my power waning. It seemed to work ok when I mixed in fish and eggs. I do question the amount of tofu that some of the vegan body builders eat but I think being happy with your body and your lifestyle is health promoting in itself so there's a balance there. I am impressed with Brendan Brazier a vegan triathlete he coinvented a meal replacement / recovery shake for vegans called Vega (nutrition info: ) its not paleo but its remarkably straight forward in its ingredients. Ive never heard of anyone working out alot eating no meat and no grains either, it seems like people lean more on one or the other in many of these diets. As I said I am back on the meat boat but I think there's a value in all of this experimentation going on within crossfit and outside of crossfit.

Jesse - Having spent some time in Mexico and seen people get all sorts of things they should not have been prescribed I would be super wary of anyone who was run out of Mexico for any Mal Practice. That's like being kicked out of the mob for being aggressive.


wrote …

So many people seem to put down the vegan diet I'm just saying there are people doing bodybuilding/fitness that seem to make it work. With more and more vegan protein powders etc coming out I feel that going vegan will soon be on par with any other diet for building muscle and longevity. My self I take Sun warrior raw rice protein and fine it works for me. I also tried vega once and it's good stuff but not cheap by any means. What about paleo or zone with out the meat would they still work if you replaced the meat with plant based protein, powders etc?


Martin, I'd consider putting this question to the mighty Robb Wolf (.com)

Sean, protein isn't protein isn't protein. My understanding is that you're still missing out on some potent goodies. If you're not vegan I guess there's plenty of room for eggs and cottage cheese to sneak in, but only you can weigh personal, ethics choices against health/performance.

You're right that there are a bunch of people doing very well on fleshless diets. Could they do better on meat? Maybe? Is it worth it to them? Clearly not. Chip Conrad at is one such dude, with CrossFitesque leanings.


Haha, I totally agree, I was posting that stuff to show that the Dr's the other guy was talking about may not be all that credible! As for being vegan, it certainly makes sense that you could be successful as long as your intake of all three macro nutrients was adequate, particularly your protein. I know soy has had a bad rap recently but from what I've read, most of the issues seem pretty overblown.


replied to comment from Jay Guindon

I think he just wants to get across that people need to have a comfort zone. So when they change their diet little by little it will work for them in the long run. I am have been trying to get people to live healthier and throwing them into the zone most of the time dosen't work. But if I try to limit the crap now and slowly change the way they eat I think it will get long term results. Long term would be healthier food lower crap calories and live longer. That's my take on it anyway.


wrote …

5 fries


wrote …

I didnt get the impression that they ended the conversation, is there more after Part5?

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