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In his book, " Girth Control ," ...

Posted Sep 11 2008 3:30pm

In his book, “ Girth Control,” nutritionist Alan Aragon reviews some of the more popular fad diets that have been popularized in recent years. Today, I’d like to review “The Zone” diet by Dr. Barry Sears using a mix-n-match of both Alan’s thoughts and mine.

Enter the Zone

Author’s Credentials: Barry Sears, PhD, is a former MIT staffer, who holds 12 patents on intravenous cancer drug delivery systems.

Summary: 40% carbohydrate, 30% protein, 30% fat - every meal must be constructed this way in order to stick to the plan. The aim is to control insulin levels to combat body fat storage and prevent the overproduction of “bad” eicosanoids. Foods with high glycemic index are viewed as obesity agents.

Pros: It decriminalizes dietary fat, and recognizes the health benefits of monounsaturated fatty acids like those in olive oil. As much of an oxymoron as it may sound, you have to eat fat to lose fat and Sears does a fantastic job at espousing the many benefits of including more “healthy” fats into your diet. Some interesting light is shed on the autocrine, paracrine, and endocrine systems that play major roles in governing the body’s physiology. It is not strict on total carbohydrate restriction as other diets, which preserves some of the sanity of the dieter.

Cons: This plan is very difficult to follow since it involves the constant precise combining of macronutrients in a specific ratio. In a nutshell, not many people have the time (or patience) to make sure that every meals consists of 40% carb, 30% protein, 30% fat.

When someone places protein, carbohydrate, or fat requirements in terms of percentages for a diet, it doesn’t necessarily have any relevance to what that person actually needs. A diet consisting of 30% protein may be too little for one person (ingesting only 1000 kcals per day) and too high for someone else (ingesting 5000 kcals per day). Granted this is an extreme example, but hopefully you get my point.

Using the above example, someone who “needs” 150 grams of protein would only be ingesting 75 grams of protein per day on a 1000 kcal per day diet (half of what he actually needs), and 375 grams of protein per day (more than double what he needs) on a 5000 kcal per day diet (again, assuming 30% protein).

Additionally, many diets are often labeled “high carbohydrate or high fat” when a specific macronutrient is over a certain percentage. Most dieticians would be quick to label a diet consisting of 35% fat as “high fat.” However, if we were to take a 2000 kcal diet (with 35% of calories coming from fat) and add 200 grams (800 kcals) of carbohydrate to it without changing anything else (total calories are now 2800), a “high-fat” diet all of a sudden becomes a “low-fat” diet because the percentage of fat dropped from 35% to 25%, even though total grams of fat stayed the same.

Lastly, Sears overlooks many aspects of glycemic and insulinemic responses as they relate to varying physiologic states (ie: training, post-training, hypocaloric, hypercaloric, etc) that either conflict with, or do not apply to his plan.

Example: it’s been shown in numerous studies that when total calories are decreased (usually in the form of carbohydrate restriction), protein requirements do indeed go up. The Zone doesn’t take this into consideration. Conversely, when someone is hypercaloric (and hence taking in more carbs), protein requirements decrease since carbohydrates are protein “sparing.”

Conclusions: All in all, this is actually a healthy plan (granted the imposed caloric deficit is not severe), but it overlooks certain principles of glycemic response, and each meal being the same macronutrient composition makes it difficult to follow long-term.

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