The Truth About The Zone Diet

The Zone Diet was developed in 1995 by Dr. Sears, a self-proclaimed anti-inflammatory nutrition pioneer and Nobel Prize in Medicine. While fad diets come and go, the Zone Diet claims to be more than that, and has remained relevant over time. In fact, since Dr. Sears' first book, the 1995 New York Times bestseller "The Zone," he has continued to publish Zone-related books up until 2019.

According to the diet's website, the Zone Diet is a "lifelong dietary program" crafted to help reduce inflammation in the body caused by poor dietary choices. By doing so, it claims to help you lose excess weight at the quickest possible rate, maintain long-term wellness, slow the rate of aging, and boost physical and mental performance — meaning that it'll help you improve your athletic potential and think faster — all while making the least effort.

In essence, the Zone Diet is a low-calorie, low-carb, high-protein diet with its own food pyramid that tells you what foods to eat and avoid and how much to eat. While some may find it restrictive or difficult to follow, others swear by its success. But is it truly as groundbreaking as it claims, or is it just another well-marketed fad?

The diet's name references its ultimate goal, which is to get you to "The Zone." As explained by Dr. Sears, The Zone is an ever-changing physiological state — meaning that it is linked to how your body functions. It is also highly influenced by your food choices, and being in The Zone is how you reduce inflammation and allow your body to heal, repair inflammatory damage, and slow down aging. According to the diet's founder, The Zone can be measured by three blood markers: the arachidonic acid (AA) to eicosapentaenoic acid (EPA) ratio or AA/EPA ratio, glycosylated hemoglobin or HbA1c test, and the triglyceride (TG) to high-density lipoprotein (HDL) cholesterol ratio.

The AA/EPA ratio measures inflammation. If the ratio is balanced or within a 1.5–3 range, then your ability to control pro-inflammatory hormones is optimal. The HbA1c test measures your long-term blood sugar control and the activation of the enzyme AMPK. This marker tells you about your ability to repair damaged tissue, and is inhibited by high blood sugar levels. Thus, your HbA1c's ideal score would be under 5%.

Lastly, the TG/HDL ratio measures insulin resistance, which is linked with increased body fat. Ideally, your TG/HDL ratio values should be under 1. If all three are within the proposed ideal values, you're in The Zone. Otherwise, you might be in an unhealthy pro-inflammatory state. While dietary changes show almost immediate improvements, getting to The Zone can take up to three months.

The Zone Diet states that restricting grains and starches and prioritizing fruits, veggies, and proteins is how you improve your hormones and reduce inflammation. Additionally, the diet calls for meals and snacks with the right balance of macronutrients — that is, carbs, proteins, and fats — and uses a portion control system called Zone Food Blocks, which claims to be the most precise way to get you to The Zone.

The diet assigns one block to each macronutrient, and according to the diet's Zone Food Block Guide, you need to consume a 1:1:1 ratio of protein, carb, and fat blocks per meal. For reference, one block of protein equals seven grams of the nutrient. In contrast, a block of carbs equals nine grams, and a block of fats equals one and a half grams if consuming an animal protein or three grams if consuming a plant-based protein. The diet also offers a Body Fat Calculator, which gives you a personalized recommendation on how many blocks to eat per day — though women typically consume 11 blocks and men consume 14 blocks.

However, another (much simpler) way to follow the diet is to fill one-third of your plate with proteins, and the rest with colorful vegetables and little fruit, prioritizing those with a low glycemic index (GI) — the ones that won't cause your blood sugar levels to spike. Finally, you could add a few healthy fats to your meal, like olive oil and avocado.

Since the diet aims to limit the impact of foods on insulin levels to reduce inflammation, it restricts certain types of carbs. In fact, the Zone Food Block Guide recommends consuming condiment-sized amounts of grains and starches or even eliminating them altogether.

However, by doing so, the diet removes important dietary fiber sources that provide numerous health benefits. A 2015 review published in Clinical Diabetes states that high intakes of whole grains and legumes are associated with significantly lower diabetes and heart disease risks.

Foods to avoid in the Zone Diet are those labeled as poor on the list. Non-recommended carb sources include grains and starches such as bread, pasta, breakfast cereals, potatoes, tortillas, crackers, granola, and rice, and selected fruits and vegetables like bananas, dried fruit and fruit juices, corn, and peas. Added sugars like jams, sodas, sweets, and sauces should also be eliminated. Similarly, the diet restricts unhealthy fats, such as saturated and trans fats.

The Zone Diet has six basic and simple rules or tips to get you in The Zone within 24 hours, as stated on the diet's website.

Rule number one is to have one zone meal or snack no more than one hour after waking up. After that, each zone meal should curve your hunger for up to six hours, and each zone snack for about two hours. Rule number two is to eat your protein first at every meal, regardless if it's a meal or a snack. Rule number three is related to rule number one. Since each zone meal is designed to keep you feeling full for two or six hours, you should eat small frequent meals throughout the day, whether you're hungry or not. In fact, it claims that the best time to eat is when you're not hungry, as lack of hunger is a so-claimed sign that you're in The Zone.

Rule number four promotes the intake their omega-3 fatty acids and polyphenols supplements, and rules number five and six encourage you to drink at least eight glasses of water per day and keep the effort going, respectively.

According to the Centers for Disease Control and Prevention (CDC), heart disease is the leading cause of death in the United States, with coronary artery disease (CAD) being the most common type, affecting over 20 million adults. The CDC also states that following healthy dietary habits such as eating plenty of fresh fruits and vegetables and limiting your intake of sweets, alcohol, and unhealthy fats — as suggested in the Zone Diet — may help prevent heart disease.

Among popularly healthy dietary patterns, the Mediterranean Diet is one known for its beneficial effects on heart health. Per a 2019 study published in the Cochrane Database of Systematic Reviews, the Mediterranean Diet is associated with increased lifespan, improved quality of life, and reduced complications and deaths from heart disease, cancer, and other chronic conditions. It is also linked to beneficial effects on heart disease's risk factors, such as high blood pressure.

But how does this all link to the Zone Diet? Well, as it happens, the Zone and Mediterranean Diets share multiple similarities. As explained by Dr. Sears, both diets emphasize fruits and vegetables, prioritize lean proteins such as chicken and fish, and rely on olive oil and nuts as their primary sources of fats. As such, the Zone Diet may also benefit your heart health.

There are a couple of reasons why following the Zone Diet can be hard in the long run. First, as stated in a study published in the Journal of the American Dietetic Association, dietary patterns such as the Zone Diet, which limit carbohydrate intake and are very restricted in calories, can be very difficult to adhere to — meaning that people are less likely to follow its recommendations or stick to it, and thus won't achieve their goals.

Second, the diet's food block method is a complicated way to measure your protein, carb, and fat intake, especially when you're not in charge of cooking your meals, which makes eating out quite challenging. In addition, tracking your food intake to ensure you're consuming the right amount of nutrients adds difficulty to the diet, which decreases the likelihood of committing to it in the long term.

Despite affirming to improve your overall health and slow down aging, there are some who suggest that the Zone Diet is based on unsubstantiated claims. On the one hand, a Sports Medicine review points out that proponents of the diet conveniently ignore contradictory data regarding its purported effects on improving hormonal balance.

On the same note, another review published in the Journal of the American College of Nutrition suggests that there are scientific contradictions in the diet's hypothesis that should make you question its efficacy. For instance, it explains that the diet oversimplifies how some nutrients affect your hormonal balance (and thus, inflammation). It also proposes that the notion that carbs are to blame for most chronic diseases fuels carbophobia — or the unfounded fear of eating carbs — a form of nutrition misinformation that has been difficult to combat throughout the years, despite what scientific evidence says.