Dietitians sound off about eating Zone blocks, and whether this could be your secret to weight loss and health success.

By Karla Walsh
December 11, 2019

For the past 25 years, millions of people (including Jennifer AnistonSandra Bullock, and many, many more) have signed on to follow the Zone Diet, created by Barry Sears, Ph.D. It promises decreased inflammation, little to no hunger, and optimal wellness...but does following the Zone diet really deliver results on the scale and promote overall health and longevity?

What Is the Zone Diet?

"The Zone Diet is designed to control diet-induced inflammation, which Sears believes is the reason we gain weight, grow sick, and age faster," says Lauren Harris-Pincus, M.S., R.D.N., founder of NutritionStarringYOU.com and author of The Protein-Packed Breakfast Club. (Check out 15 anti-inflammatory foods you should be eating regularly.)

Once you're "in the Zone," you have limited that hormone-triggered inflammation that Sears swears is the cause of weight gain and premature aging. A combo of high insulin (which has been linked to weight gain and certain cancers) and high omega-6 fatty acids in the body are two culprits that can lead to inflammation, and later, obesity, according to Sears. While you do need some omega-6s, excess levels may lead to higher heart disease risk.

Supposed Benefits of the Zone Diet

There are three physiological markers Sears says you can look to determine if you've reached "the Zone."

  • Your triglyceride to HDL cholesterol ratio is less than 1.

  • Your AA to EPA (arachidonic acid / eicosapentaenoic acid) ratio, a marker of cellular inflammation that relates to omega-3 fatty acids in the body is 1.5 to 3.

  • Your Hemoglobin A1c level (aka blood sugar) is around 5 percent.

The Zone Diet promises that when you're in the Zone, you think quicker, perform better physically, avoid illnesses, and shed pounds at "the fastest possible rate," according to their website. The theory Sears put out is that inflammation throws off hormonal communication within cells, hampering efficiency, and therefore performance.

What You Can Eat On the Zone Diet and How Much

Carbs, protein, and fat are all allowed on the zone diet, but in very specific ratios.

"You eat 40 percent carbs, 30 percent protein, and 30 percent fat at each meal and snack," explains Julie Upton, M.S., R.D., a San Francisco-based registered dietitian and co-founder of the nutrition news company Appetite for Health. "It requires you to track what you're eating and aim for balance at each meal." (Related: Your Complete Guide to the 'IIFYM' Or Macro Diet)

Sears points to a few medical studies that demonstrate a general trend toward weight loss, fat loss, and less cellular inflammation with this 40/30/30 ratio.

Each macro is translated into Zone Diet "blocks", which are meant to make tracking simpler but can take some time to get used to, says Harris-Pincus. Your total allowance of Zone Diet blocks will vary based on your results with the Zone Diet Body Fat Calculator, which helps estimate how much energy your body requires based on size and activity. You can download a Zone Food Block Guide online, which breaks down the blocks per food even more. They roughly translate to:

  • 1 Zone Diet block of protein = 7 grams of protein

  • 1 Zone Diet block of fat = 1.5 grams of fat

  • 1 Zone Diet block of carbs = 9 grams of carbs

No foods are completely off-limits, but many common ingredients are given a general ranking of "best" (Brussels sprouts, egg whites/substitute, salmon), "fair" (cheese, whole eggs, potatoes), and "poor" (bacon, rice, ice cream). Zone Diet followers are supposed to limit carbohydrates that are high on the glycemic index, which is an indicator of how quickly carbs are digested and therefore how quickly blood sugar can spike and fall, as well as sources of saturated fat. (Related: Is Butter Healthy? The Truth About Saturated Fat)

Lastly, Sears suggests eating at least every five hours on the Zone Diet to balance fuel throughout the day and avoid highs and lows in your energy.

Problems with the Zone Diet

Any diet that has a list of "unfavorable" foods is a hard pass for me, says Jenna A. Werner, R.D., creator of Happy Slim Healthy. "I don't believe in assigning foods with labels such as good and bad—that gives food control over us. The idea of telling someone 'no' creates a sense of restriction, and study after study shows us that restriction leads to binging. Instead, I believe in educating people on how to eat, how to include foods that are important to them into their lives, while educating them on how to prioritize whole and nutritious foods." (Related: We Seriously Need to Stop Thinking of Foods As 'Good' and 'Bad')

Harris-Pincus agrees, saying "any diet that discourages several kinds of fruit gives me pause. Prunes—which are excellent for bone health—plus bananas, cantaloupe, watermelon, mangoes, pineapple, figs, honeydew, limes, and cranberries all rate as 'poor' on the Zone Diet."

The portion size of some Zone Diet blocks (see the Zone Diet Grocery Guide for some examples) seems unrealistic to Harris-Pincus too.

"Three cashews?" she asks. "One and on-third teaspoons of olive oil? How does one measure that exactly? I also question any diet that sells supplements to accompany the plan, especially when they are pricey. The Zone Diet offers omega-3 and polyphenol supplements. There are also protein powders and snack bars, which are highly processed and contain more sugar than some other competitor products." (For example, a 220-calorie ZoneRx Chocolate Crispy Nutrition Bar has 15 grams of sugar—just shy of 4 teaspoons.)

The branded foods don't come cheap either: A one-pound box of that Zone "PastaRx" Fusilli pasta, made with durum wheat, wheat protein, dried egg whites, and more, will cost you $16. (Compare that to $1.49 for a same-sized box of Whole Foods Market's 365 Everyday Value Organic Fusilli on amazon.com.)

While Werner appreciates the focus on whole foods, fruits and veggies, lean proteins, and healthy fats, she's not quite so sure about the caloric breakdown of the Zone Diet.

"Women are allowed roughly 1,200 calories per day," she says. "This is inadequate to support most peoples' needs and creates a caloric deficit that is simply way too large to be sustainable or healthy." (Related: How Many Calories are You *Really* Eating?)

So, Is the Zone Diet Healthy?

"I think it's nutritionally sound for the most part compared to other trendy diets," says Harris-Pincus. Plus, decreasing inflammation and aiming to fill your plate with lean protein, veggies, and healthy fats are both solid health concepts.

"There are certain principles of this program that you can certainly carry with you for your entire life," adds Werner. But "ask yourself before starting this program, 'can I do this forever? Does this make me happy? Can I do this on vacation? Can I do this on Thanksgiving? Any holiday? Every holiday? Every day?'," she asks.

If you find that a strict diet makes you skip dinners out with friends or feel rigid when a dinner party doesn't perfectly fit the Zone Diet breakdown exactly, seek out other options that are easier to stick to and require less tracking (such as the low-stress, heart-healthy Mediterranean Diet plan). Or "work with a dietitian to design a custom nutrition program that will teach you how to feed yourself in every scenario—and enjoy it too," says Werner.

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