Enter the Zone by Barry Sears10 min read

I recently tried my hand at CrossFit and the figureheads in this space often recommend the Paleo and/or Zone approaches to nutrition to maximize performance. Not knowing a whole lot about nutrition, I wanted to see what all the hype was about. There are several “Zone” books out there but this review is of the original, published in 1995 by Dr. Barry Sears. Although a bit dated, I still found it very relevant. Here is his gospel:

Dr. Sears defines the zone as being “the mysterious but very real state in which your body and mind work together at their ultimate best”; he compares it to the sport expression of feeling like you are in the zone, like you are on top of your game. The book has a lot of content, examples and technical information on nutrition which I won’t want to cover holistically but here are my main takeaways:

Dr. Sears starts by challenging the 90’s conventional nutritional wisdom used to combat the American obesity epidemic; in short, to encourage low fat, low protein diets that privilege carbohydrates as the main source of energy. The underlying logic being if you don’t eat fat, you should start losing it. Logical enough for the nutritionally illiterate, right? However, Dr. Sears retorts: “You fatten cattle by feeding them lots and lots of low-fat grain. How do you fatten humans? Same way: you feed them lots and lots of low-fat grain.” The tone was set for the book and my interest was piqued.

Whenever you read on nutrition, the three main macro-nutrients (Carbohydrates, or Carbs, Protein and Fat) always make an early appearance and this book was no different. The Tres Caballeros come up time and time again and are central to the Zone framework. Here are the points made:

Carbohydrates

Your brain mainly uses carbohydrates as an energy source, however, you have very limited storage capacity for carbs in your system (only muscles and the liver can store carbs and only the liver’s storage can be used to power the brain). All told, you can probably only store around 400-500 grams at once. Once all stores are full, excess carbs start making your blood sugar levels rise. This triggers insulin hormone release to convert these excess carbohydrates and store them as fat (which has no storage limit) to control the blood sugar rise. It also hinders the use of fat as energy when present in the bloodstream. However, not all carbs enter the bloodstream at the same rate.

The glycemic index identifies the rate at which a carbohydrate will enter the bloodstream once consumed. Eating low glycemic index carbs will promote sending energy directly to the brain as it will “bathe” in your stomach longer whereas high glycemic index carbs will be absorbed quickly, max out brain demands and be sent for storage as fat (quantity obviously also plays a role here).

Protein

As Dr. Sears puts it, “Protein is the main structural ingredient of our cells, and the enzymes that keep them running.” Each person has a protein requirement based on Lean Body Mass (LBM) and Activity Factor (formula in the book), you should aim to eat just that amount per day since higher amounts will also trigger insulin responses and get converted into fat and lower amounts will affect how the lights stay on in different parts of your body (ie. Protein will be diverted from muscle and converted into carbs to feed the brain and your muscle mass will decrease).

Fat

At this point, Dr. Sears introduces the notion of hormone axes, mentioning that hormones are involved in a balancing act of sorts, meaning there is always a Ying to each hormonal Yang. This will be important in a second. Eating fat does not make you fat. In fact, you must eat fat to lose fat.  How? If you eat the appropriate amount of protein and carbohydrates for your personal needs you will need to eat fat for the remaining calories.  Your insulin-glucagon axis (hormones that regulate blood sugar levels) will be in balance and the fat you eat (plus your body fat) will be your primary source of energy. Fat also serves to slow the entry rate of carbohydrates into the bloodstream, is the principal macro-nutrient that gives flavor to food and triggers the release of the cholecystokinin hormone in the stomach which tells your brain you are no longer hungry.

Zone Framework

After discussing the macro-nutrients, some hormonal axes and the role of eicosanoids in the body, Dr. Sears outlines his Zone nutritional framework to attain optimal levels of body function. In a nutshell:

• Find out your personal daily protein requirements (in grams) and always aim to consume exactly that amount (formulas provided in the book).
• Your protein requirements will represent a 0.75 ratio of the amount of carbohydrates you need (e.g. for each 1g of carbs you would eat 0.75g of protein)
• Additional fat is required on top of fat usually contained in your protein sources (ie. Meat) to ensure you meet your daily requirements.
• Spread your meal and macro-nutrient consumption as evenly as possible throughout the day (Sears suggests three meals of similar size and two snacks) to keep a balanced, steady furnace running.
• To make the four previous points manageable, Dr. Sears suggests breaking down your meals into “blocks” to make recipes easier. 1 block of protein is 7g, 1 block of carbs is 9g and 1 block of fat is 1.5g.  You should always eat in multiples of 3 blocks of each macro-nutrient (e.g. a 3-block meal would contain 3 blocks of protein, 3 blocks of carbs and 3 blocks of fat).  This sounds complicated but if you look up Zone recipes, they are all built in this fashion.  It also makes it easier to make a meal plan because you can plan for the appropriate number of blocks every day (ie. Divide your day in 16 blocks: three 4-block meals and two 2-block snacks).
• Never let more than 5 hours pass (except for sleep) in between meals (steady furnace…)

Other Interesting Points

• Think of food as medication. When you are eating, you are influencing your chemistry as much when you take medication. However, medication is usually aimed at moving a specific needle which can produce side effects because the intervention is so targeted on a specific metric. This rarely happens when you eat a balanced diet of complex foods because you are moving a whole bunch of needles in concert at a slow and steady pace.
• Think of the body as a manufacturing plant. If you feed it a steady, balanced diet, your outputs (energy levels, etc) will also be steady and balanced. If you are constantly changing recipes or adding excessive amounts of a single ingredient at one point in time, you will have very different and varied outputs based on those inputs.  Similarly, if you load a high volume of inputs and let the machine run all day before inputting raw material again, the outputs (energy levels) will be of lower quality as time moves forward as the machine starts running on fumes. This is why Dr. Sears advocates eating lots of small meals and balancing each one of those meals.
• You can’t really lose fat at more than a rate of 1-1.5 lbs per week. If you lose more weight in that amount of time you are also losing either water or muscle mass.
• The human growth hormone (secreted during high intensity anaerobic activity) is tasked with repairing muscle tissue after exercise. It takes most of its energy to do the job from fat.

Obviously, this is a lot of information to take in and following the framework religiously would be a bit extreme. However, what is the goal when looking at nutritional frameworks? Ultimately, it’s about eating better and getting better outcomes, whether they be health or performance related. I think this book serves that purpose even if you don’t want to start counting blocks for a living as there are general, practical rules given that you can easily apply to your nutrition for better outcomes.

What I liked.

• Contrary to most readers of the book, I was happy the author was not scared to go in the technical weeds and talk about different hormones, body functions, etc. to support his recommendations. The theoretical concepts presented expose a first-time nutrition reader to a whole slew of concepts that can be investigated further if needed but also allows the book to stand of its own right without oversimplifying the subject matter too much. It is a mass market book after all…
• Even if you choose not to follow the Zone methodology after reading the book, there are loads of practical things you can easily implement to have an overall better diet.
• The bibliography was laid out by chapter which gave easy leads for further reading on concepts that were of interest.
• The appendices added tremendous value by making worksheets available to put the framework in place in your own life. The author makes it as easy as possible to implement the method.
• You all know I’m a fervent believer in indexes. This index was superbly executed; it will be easy to come back to this book for a single fact and being able to find it quickly.

What Could Have Been Better

• There was LOTS of repetition throughout the book. It could most likely have been condensed into less chapters.
• The book did not address sugar and given the recent attention it is getting in the media, I would say this is one of the only aspects that reveals the book’s age.
• The sample sizes for the research presented was always very small (5-20 people). The author explains that this is because the research was self-funded but this gives skeptics all the ammo they need to dismiss the method without looking into it.

3 Favorite Passages

• “Nutritionists hate the French because they have low rates of heart disease, but they still manage to have a good time. They eat a high-fat diet, they don’t exercise, and they drink wine.” (Hilarity)
• “Calorie restriction – coupled with the correct macronutrient composition – is far more effective than any drug in the prevention or treatment of cancer” (Because now I have more reading to do… Pretty bold claim)
• “During the course of my personal odyssey into understanding the nutritional code […], I kept coming back to fundamental common sense – everything in moderation.” (We all know this already.  We just need to define what that means personally.)

Rating: 3/5

Do I think Dr. Sears has revealed the secret formula for perfect nutrition in his book? No – It would be too simple. However, the zone framework is constantly presented as such in the book and this clouds the fact that it presents a perfectly reasonable way of eating. Though, this might very well be why the book is still selling two decades later: outstanding marketing for a reasonable product.

Personal Library Worthy?  Depends. If you already have some literature on nutrition that covers the basics, allows you to make actionable, positive changes to your diet and is structured in such a way that you can pull it for 10 minutes and get immediate, practical value, then I wouldn’t add this book to your collection.  However, if you’re looking for the former, then this is a good place to start.

*Note: Should you be interested in looking at what the Zone Meal Plans look like, check out Issue 21 of the CrossFit journal. It is a great, free primer on the topic.

———————————
What are your thoughts on nutritional frameworks? Do you feel they help optimize your diet? Or are they too rigid and therefore a waste of time? Let me know in the comments.

Last Updated on December 22, 2020 by Joël Collin-Demers