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 Zone Diet is a dietary program that focuses on reducing diet-induced inflammation, which is known to play a key role in the development of chronic diseases and aging, per a 2021 study published in Redox Biology. As a video on Dr. Sears' website states: "This inflammation is the reason you gain weight, become sick, and age faster." Therefore, Dr. Sears proposes that the Zone Diet can reduce the levels of inflammatory hormones called eicosanoids. By doing so, it reduces the risk of chronic conditions such as diabetes and heart disease.

Furthermore, some evidence suggests that there might be some truth behind the diet's claims. According to a 2015 study published in the Journal of The American College of Nutrition that evaluated the effects of a zone-style diet in people with type 2 diabetes, modern nutrition seems to be the cause of increased inflammatory responses. Thus, reducing diet-induced inflammation offers a wide range of health benefits, including improved blood sugar control, reduced body weight, waist measurements, fat mass, and a better overall hormonal balance.

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 complete Zone Anti-Inflammatory Nutrition Program is what would get you to The Zone, and the diet is just one of three components. In fact, the diet is meant to reduce the generation of inflammation, while the remaining components are designed to enhance the resolution of current inflammatory processes.

The second and third components of the program rely on proprietary supplement blends. One focuses on providing sufficient omega-3 fatty acids, and the other on increasing your intake of polyphenols, which are known for their multiple health benefits. For instance, per a study published in the British Journal of Clinical Pharmacology, omega-3 fatty acids have powerful anti-inflammatory effects. Similarly, polyphenols seem to play a role in reducing inflammation (via Healthline).

In addition, complementing the diet with these supplements is supposed to improve your blood markers — which will, in turn, get you closer to The Zone. Per Dr. Sears, omega-3 fatty acids are the best way to get your AA/EPA ratio in range. At the same time, polyphenols will purportedly improve your HbA1c levels.

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.

The Zone diet follows a food pyramid with vegetables at the bottom, followed by fruit, low-fat protein, healthy fats, and grains and starches at the top. To make things a bit easier, the diet classifies foods as fair, best, or poor, and the Zone Food Block Guide offers a list designed to help you make the best possible food choices. Some recommended protein choices include turkey, skinless chicken, fish, egg whites, tofu, low-fat dairy, very lean meats, and plant-based meat substitutes.

When it comes to carbs, the diet emphasizes fruits and vegetables with a low GI to avoid spiking your blood sugar levels and stimulating insulin. Preferred carb sources include artichokes, asparagus, Brussels sprouts, broccoli, spinach, kale, mushrooms, cauliflower, strawberries, blueberries, raspberries, blackberries, oatmeal, and barley.

Finally, fats are encouraged in small amounts only to help curb hunger, focusing on monounsaturated fats. Some recommended fat sources are olives and olive oil, nuts and nut butters, avocados or guacamole, and tahini.

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 is not a quick fix or short-term approach to losing weight. Instead, you should look at it as a means to help you maintain wellness for as long as possible. As such, it is based on four pillars that, when put together, are supposed to get you closer to enjoying your best health. Nevertheless, note that the best way to balance the pillars is by following the diet and consuming its proprietary omega-3 fatty acids and polyphenols supplements.

According to Dr. Sears, the first pillar is to restrict calories without hunger or fatigue, meaning that you should eat the least amount of calories possible without compromising your energy levels to burn excess fat. The second pillar is to maintain an appropriate balance of inflammation in your body, because some inflammation is normal and even needed. What is not normal is when your body's inflammatory response doesn't turn off.

The third pillar is to use polyphenols to activate wellness genes, seeing that polyphenols from colorful fruits and vegetables (and supplements) help fight inflammation and aging. Lastly, the fourth pillar is to control inflammation caused by your gut's friendly bacteria, also known as your microbiota. Dr. Sears explains that a specific bacteria called Akkermansia muciniphila is key to managing gut-related inflammation, and that feeding it with fiber, omega-3 fatty acids, and polyphenols helps it multiply, thus improving your inflammatory status.

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.

Per a 2017 review published in Nutrients, the Zone Diet has a macronutrient ratio of 40% carbohydrates, 30% proteins, and 30% fats, with a mean calorie recommendation of 1,500 calories per day for men and 1,200 calories per day for women. Therefore, the Zone Diet can be classified as a low-calorie, low-carb, high-protein diet, and thus, it most likely leads to weight loss.

The review shows that a 6-month study in 30 women with overweight and obesity who were following the Zone Diet lost about 7% of their initial weight — about 6.9 kilograms. Similarly, it states that another study in 40 adults with overweight and obesity had an average weight loss of 3.2 kilograms after a year of following the diet.

However, both this review as well as another one published in the Cochrane Database of Systematic Reviews found that low-carbohydrate diets for weight loss had little or no difference in short-term and long-term weight loss outcomes compared to balanced-carbohydrate diets, which means that the main reason behind their success is due to their calorie restriction and not their carbohydrate restriction.

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.

The Zone Diet may also help you control your blood sugar levels, which, according to the CDC, is the most important thing to do to manage diabetes and prevent diabetes-related complications. In fact, the diet's guidelines of prioritizing low GI carbs, filling a third of your plate with non-starchy vegetables, eating lean proteins, choosing healthy fats, and limiting processed foods are healthy dietary habits that could even help you prevent type 2 diabetes (per Livestrong).

According to a meta-analysis published in Nutrition, diets with low GI such as the Zone Diet are more efficient in managing fasting blood sugar and glycosylated hemoglobin or HbA1c — a measure of long-term blood sugar control — compared to high-GI diets in people with type 2 diabetes.

Furthermore, a 2015 study published in the Journal of the American College of Nutrition explains that inflammation is directly associated with obesity and obesity-related complications, and that by choosing low GI foods and supplementing with omega-3 fatty acids, the Zone Diet reduced inflammation, showing real-life improvements in blood sugar control in people with type 2 diabetes.

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.

The Zone Diet claims to reduce inflammation, enhance your thinking abilities, and improve athletic performance. However, evidence shows contradictory results on the diet's effect on athletic performance.

Per a small study in eight endurance athletes published in the Journal of Strength & Conditioning Research, the Zone Diet is not a nutritional strategy that should be recommended for athletes. According to the study, the diet's calorie restriction reduced the athlete's running time to exhaustion — a measure of exercise performance. This means that when asked to run for as long as possible, their running times were lower than those on a normal diet.

Similarly, a review published in Sports Medicine states that the diet impairs athletic performance instead of improving it, and that many of the Zone Diet's alleged benefits are based on selective information. For example, the diet claims to improve oxygen delivery to exercising muscles. Yet, while the principle is theoretically correct, the little available human evidence proves otherwise.

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.