Zone Diet Review: Barry Sears' 40/30/30 Diet - Diet Reviews

Zone Diet Review: Barry Sears’ 40/30/30 Diet

The Zone Diet, the popular diet by Barry Sears, is also commonly referred to as the 40/30/30 diet. “40/30/30” refers to the proportion of each food group in the diet. In this case, 40% of daily caloric intake comes from carbohydrates, 30% comes from protein, and 30% from friendly fats.

The Zone Diet is all about getting into that mysterious place Sears calls “the zone.”

What the heck is “The Zone?”

According to Sears, this is the place where athletes perform better, where mental focus is enhanced, and life is generally a better place. Getting there is a simple matter of changing your eating patterns to reflect the 40/30/30 ratio, which, Sears argues, is the best way to stabilize blood sugar, promote general well-being, and encourage weight loss.

Yeah, yeah. But why 40/30/30?

What’s the rational behind this ratio of macronutrients?

Balancing Hormones

The whole point of this 40/30/30 ratio is to balance two main metabolic hormones – insulin, which promotes the storing of excess calories as fat, and glucagon, which promotes the burning of fat. Sears also claims The Zone diet also promotes a positive balance of the body’s microhormones (called eicosanoids), although he does not present any clinical evidence to validate this statement.

As a weight loss book, “Enter the Zone”, isn’t too bad a read. Unfortunately Sears ventures off track enough during his discussion of eiconsanoids to give even the most dedicated of dieters a severe case of boredom.

Chapter 7: Boundaries of the Zone

intermittent fastingIf you’re going to give this diet a shot, it’s essential you read and understand chapter 7 – “Boundaries of The Zone.” In this chapter Sears maps out the entrance points to “The Zone.” It’s crucial that you know this “40/30/30 ratio” is only the mid-point of this entrance-way.

You will have to adjust your carbohydrate intake according to your personal sensitivity to them in order to find your personal entrance to the “zone”.

The main problem for the average dieter will be finding this sweet spot (i.e. your unique entrance point to “the zone”).

This is crucial to the entire plan — if you don’t find it, you won’t lose weight. And if you’re hypoglycemic or hyperinsulinemic or have problems with blood sugar it’s likely that 40% of total daily calories from carbs is too much!

If this is the case, I recommend you start with a smaller percentage of daily caloric intake from carbs, and increase them only if you can.

The Zone Diet: Pros and Cons

Let’s outline some pros and cons of this diet…

The Zone Diet “Pros”:

  • Since you are not significantly restricting any one food source in Sears’ diet, you are never totally deprived of the foods you love.
  • If you successfully find your entrance to “The Zone” you will experience slow, gradual, and permanent weight loss.
  • The main purpose of this diet plan, that of balancing insulin and glucagon, is fundamentally correct!

The Zone Diet “Cons”:

  • The 40/30/30 macronutrient ratio represents the “mid point” to the entrance way of the mysterious place of which Sears speaks. You have to play around (by adjusting carbohydrate intake), find your own entrance way. This can be tricky.
  • The daily caloric intake for this diet is determined by your protein requirements – which can lead to incredibly low daily caloric intake – much too low!
  • Claiming the 40/30/30 zone ratio creates a positive eicosanoid balance isn’t a bad theory, but it’s a largely unproven one.

All in all, I’d have to say Barry Sears’ diet is probably worthwhile buying and trying – if, and only if, you can read it from cover to cover, and can commit to some “messing around” getting your macronutrient ratio correct.

Author: Paul

Paul Crane is the founder of His passions include supplements, working out, motorcycles, guitars... and of course, his German Shepherd dogs.


  1. Nice post. It’s all about keeping that insulin-glucagon teeter-totter in check and eating a balanced diet. The body knows of only 3 food groups and functions best with the proper amount of each (protein, fat and carbs).

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  2. I have been on this diet for a year now. I’ve lost 95lbs. and there’s no turning back. I love the way it makes me feel. It is a bit tricky though. I’ve had to recalculate my ratio, and can’t find my perfect spot.



    Editor’s comments: This is an individual thing; something you just have to play with until you find it.

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  3. Sears has a point with the macronutrient ratios, and it is important if you are active and or you are recovering from a major physical trauma like surgery. I suspect that it may also be important for those who deal with chronic pain (like myself) but there I have not found a good scientific body of evidence to help with this conclusion. Working with your macronutrient ratios (carbs, protiens, fat) will help in numerous areas. It will help balance blood sugar levels, keep you satisfied after a meal and stabilizes moods as well (to a degree). Weight loss is a science and by following a good plan, you can loose the weight and keep it off for good.

    I stuck with a plan similar to Sear and I restricted my basic caloric intake and I lost a lot of weight. The end result was 150lbs at 5’8″ with my abbs showing. Today I am up to 210# and I need to loose about 40 lbs. When I stoped my program, I started eating more calories and the weight came back on. I am geting back to a plan like Sears again and I have not yet begun to loose weight (I am not counting calories yet), however I want to loose slowly this time (1/2 a lb per week) so I can keep my energy levels up and not feel deprived.

    good luck to everyone who following a good plan and is learning to stick with it.

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  4. I found this a good, balanced review.

    I lost 60 pounds on this diet. The key here is not the caloric intake. Use that as a starting point. Figure the GRAMS of protein, carbs, and fat needed to supply the 30/30/40 ratio of the desired caloric intake. Remember that fat delivers more calories per gram than protein and carbohydrates. Then split up the totals into three or four meal.

    It takes a bit of time to get the numbers worked out, but once you have them, stick to them.

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    • Are there nutritionist that can help you plan a 40-30-30 plan?

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      • Can you remove my last name?

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      • Almost anyone should… this is just a ratio of macronutrients (i.e., fats, proteins, carbs).

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