The Zone Diet versus Popular Diets
Zone Diet versus the Mediterranean diet
As I pointed out in my book, The Mediterranean Zone, there is no real definition of a Mediterranean diet. There are some 16 different countries that line the Mediterranean Sea and the cuisine is very different in each country. (For example, only in Italy do people eat a lot of pasta.) However, all the diets of this region put an emphasis on fruits and vegetables, just like the Zone Diet. Also, fish and chicken are the primary sources of lean protein which is similar to the Zone Diet and at consumption levels similar to the Zone Diet. Finally, olive oil and nuts are the primary sources of fat just like the Zone Diet.
The major difference between the Zone Diet and the Mediterranean diet is the reduced intake of grains (breads and pasta) and starches (potatoes and rice) with a corresponding increase in non-starchy vegetables and fruits. That one seemingly small dietary difference has significant hormonal implications. By replacing the grains and starches found in the Mediterranean diet with even more vegetables and fruits, the Zone Diet represents the evolution of the Mediterranean diet with fewer calories, more fermentable fiber, and more polyphenols and with far better blood glucose control. While the Mediterranean diet is a good (even if totally undefined) diet, the Zone Diet represents a hormonally superior choice with a high degree of dietary definition that results in the reduction of insulin resistance and cellular inflammation.
What about the studies that “prove” the Mediterranean diet is the best diet? The most quoted study (Prevention with the Mediterranean Diet or PREDIMED) was designed so show that changing the diet of individuals (primarily located in the Spain) to a more Mediterranean diet could be useful in preventing cardiovascular disease. Initially all the subjects were eating a relatively high-fat diet. The subjects were then divided into three groups. One group was given free nuts and regular intensive counseling on how to incorporate the principles of the Mediterranean diet (more fruits and vegetables) into their daily diet. The second group was given free olive oil and intensive regular counseling on how to incorporate the principles of the Mediterranean diet (more fruit and vegetables) into their daily diet. The third group (the control group) was given nothing outside the advice to consume less fat.
You are probably thinking to yourself, that’s not a very good study. You are right, yet the PREDIMED study was published in the New England Journal of Medicine in 2013 and was considered the most important dietary trial in the last decade. Of course, you would never realize this design flaw by simply reading the article. You must go to the supplemental material embedded only in the electronic files of the New England Journal of Medicine. Here is what it stated:
“The initial dietary protocol for the Control group started with the delivery of a leaflet summarizing the recommendations to a follow a low-fat diet and scheduled one yearly visit. In October 2006, three years into the trial, we realized that such a low-grade intervention might potentially be a weakness of the trial and amended the protocol to include quarterly individual and group sessions with delivery of food descriptions, shopping lists, meal plans, and recipes (adapted to the low-fat diet) in such a way that the intensity of the intervention was similar to that of the Mediterranean diet groups, except for the provision of supplemental food for free.”
In essence, the PREDIMED study was not very well designed. This reason why is the control group never changed their diet to a low-fat diet. Yet this terribly designed and executed study has generated more than 200 additional papers on the “superiority” of the Mediterranean diet. In fact, this trial demonstrated two things. First, if you give people free food, they will eat it and second, it is hard for people to change their diet without giving them free food. The original study was retracted in 2018 and republished with amended results acknowledging that they should have done a more controlled study even though the data were relatively similar to the first trial.
I personally spend a lot of time in Italy and Spain and I always have the same meal for lunch and dinner: grilled vegetables as my appetizer, grilled fish with more grilled vegetables as my entrée, and fresh fruit for dessert. It works every time. Of course, I add olive oil to my meals. I guess you would call my diet in Italy and Spain the Zone Diet Mediterranean style.
Zone Diet versus Ketogenic Diets
What about ketogenic diets? A ketogenic diet is a high-fat, very low-carbohydrate diet designed to generate ketosis. Ketosis is a condition in which the liver becomes deficient in stored carbohydrates and therefore can’t completely convert fat into carbon dioxide and water to produce ATP. This deficiency of stored carbohydrates in the liver produced by following a ketogenic diet also means that there is no way to stabilize blood sugar levels between meals. Furthermore, instead of a normal clean oxidation of the fatty acids to carbon dioxide and water for the generation of ATP, you now get metabolic by-products termed ketone bodies circulating in the blood that the body tries to reduce by increased urination. The Zone Diet, on the other hand, is a protein-adequate, carbohydrate-moderate, low-fat diet that prevents ketosis.
Ketogenic diets were first made popular by Robert Atkins in 1970s, and they rise and fall in popularity with each new generation. With the resurgence of ketogenic diets in the early part of this century, I published a carefully controlled head-to-head clinical comparison of the Zone Diet and a ketogenic diet in 2006. Using overweight and obese subjects, each group ate meals prepared for them and consumed the same number of calories (about 1,500 calories per day) and the same levels of protein at each meal. The only variable was the fat-to-carbohydrate ratio at each meal. The results? The subjects following the Zone Diet lost more weight and body fat than the subjects following the ketogenic diet meaning there was “no metabolic advantage” to the ketogenic diet. In fact, those who followed the ketogenic diet saw their levels of cellular inflammation (as measured by the AA/EPA ratio) double in six weeks. Additional analysis demonstrated that those following the ketogenic diet had higher levels of fatigue when performing mild exercise and they lost calcium most likely from their bones. These are not strong selling points for a ketogenic diet.
Compared to all other high-carbohydrate diets under less controlled clinical conditions, the ketogenic diets do show more initial weight loss, but after one year there are no differences in terms of weight loss between the two types of diets. Furthermore, a very recent study under metabolic ward conditions in which all food consumed is tightly controlled demonstrated that a ketogenic diet actually generates less fat loss than a high-carbohydrate diet. More ominously, in animal studies conducted at Yale Medical School in 2010 it was demonstrated that while a ketogenic diet did reduce body total body weight and serum insulin levels, there was a significant increase of insulin resistance in the liver. This is usually the first step toward developing type 2 diabetes.
Zone Diet versus Longevity Diets
We also hear a lot of talk about areas in the world that people seem to have greater longevity and a longer healthspan. Unfortunately, most of these regions also have poorly documented birth and medical records meaning the stated ages of those being interviewed may be somewhat suspect. The only region of reported longevity that does have legitimate birth and medical records is the island of Okinawa. So, how does the Zone Diet stack up against the Okinawan diet?
There are several similarities between the two diets. First both diets tend to be calorie-restricted with the typical Okinawan diet providing about 1,800 calories per day. The Okinawans also eat significant amounts of fish, eat little rice (it’s hard to grow rice on a volcanic island), and consume more pork and tofu that other Asian populations. The carbohydrate content of the Okinawan diet comes primarily from a purple potato unique to Okinawa, which is exceptionally rich in polyphenols (that’s why it is purple). While the Okinawan diet contains fewer non-starchy vegetables than the Zone Diet, it is a calorie-restricted diet rich in omega-3 fatty acids and polyphenols making it similar to the Zone Pro-Resolution Nutrition system. Okinawa also has the highest percentage of centenarians per capita in the world as well as having the longest healthspan on the planet. This might suggest that following the Zone Diet would potentially generate the same results.
Zone Diet versus Intermittent Fasting
It’s clear that calorie-restriction can have significant health benefits. Can those benefits be enhanced or easier to obtain by adding the concept of intermittent fasting? Intermittent fasting is based on the idea that continuous calorie restriction is too hard to follow on a long-term basis. So maybe you can just do it for a couple of days with mini-fasts, knowing you can overeat the next day. In one version of intermittent fasting, you eat normally (of course this is what probably caused the weight gain in the first place) for five days and then do a limited fast of about 500 calories per day for two days. This is known as either the 5:2 diet or the Fast diet. Another version has you alternating partial-fasting days (25 percent of your normal calorie diet) with a mini-feast (125 percent of your normal calorie intake) days as reward days resulting in an overall diet consisting of 75 percent of your normal calorie intake instead of following a constantly calorie restricted diet providing 75 percent of your normal calorie intake every day. Regardless of the approach, recently published long-term studies have demonstrated no benefits of intermittent fasting compared to consuming the same number of restricted calories day in and day out. Furthermore, there is no difference in weight loss. However, the subjects were less compliant on the intermediate fasting diet—probably because they were hungrier on their mini-fasting days. The same lack of differences between consistent calorie restriction (like the Zone Diet) and intermittent fasting is also found in a recent long-term study with type 2 diabetics.
On the other hand, on the Zone Diet you are never hungry or mentally fatigued because of consistent hormonal control you can easily follow for a lifetime.
Zone Diet versus Paleolithic Diets
As I stated in my first book, The Zone, the Zone Diet was developed based on a short article describing the potential composition of Paleolithic diets published in the New England Journal of Medicine in 1985. I am very big on the idea of attribution. That’s why I included an entire chapter in The Zone (it’s Chapter 9: Evolution and The Zone) outlining the origin of what eventually became the Zone Diet.
In 2010, various academic scientists including Boyd Eaton, one of the authors of the 1985 New England Journal of Medicine article published the most up-to-date data on the best analysis of the macronutrient composition of the Paleolithic diet some 15,000 years ago. Their estimates were that it consisted of 39-40 per cent low-glycemic load carbohydrates (i.e., vegetables and fruits), 25-29 percent low-fat protein, and 31-39 percent fat. That’s close enough for me to the average macronutrient composition of the Zone Diet (40 percent low-glycemic load carbohydrates, 30 percent low-fat protein, and 30 percent fat). Moreover, it is clear that based on those macronutrient percentages that neither the Zone Diet or a real Paleolithic diet are ketogenic diets.
There are two primary differences between a paleo diet and the Zone Diet. The first difference is that the Zone Diet starts with your calculated protein requirements that are unique to you. Since the absolute levels of protein consumption is left unstated in paleo diets, this potentially could lead to the potential overconsumption of protein as well as consumption of excess calories. The second difference is that wheat, legumes, dairy, and as well as alcohol are not to be consumed on the Paleo diet because they didn’t exist 15,000 years ago. As I described in the previous chapter, the absolute elimination of wheat, legumes (as well as lectins) and dairy protein may not stand up to closer examination. Relative to alcohol, I always caution moderation to the extreme because of alcohol’s effects on developing a leaky gut as well as a leaky brain. However, I personally agreed with the recent study in Lancet that the ideal consumption of alcohol is probably zero. Other than those differences, the Paleo diet and the Zone Diet are like two peas in a pod (even though peas are legumes).