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Inside Dr. Barry Sears’ Zone Diet

  • By T.J. Murphy
  • Published Jun 14, 2013
  • Updated Oct 7, 2013 at 8:55 PM UTC
Photo: Adam Hunger


The path to developing the Zone diet began when Sears reviewed biochemistry research performed by Sune K. Bergström, Bengt I. Samuelsson and John R. Vane—research that earned the Nobel Prize for Medicine in 1982. The subject was eicosanoids, molecules that control hormones and are produced in every living cell in the body, and, as Sears describes them, are “the molecular glue that holds the human body together. Think of them as the biological Internet.” Eicosanoids were discovered in 1936, and the lab technology of the 1970s enabled an understanding of the effects of eicosanoids on both cellular inflammation and immunity.

Sears says that a basic understanding of how manipulating eicosanoids can change cellular inflammation levels can be seen with aspirin. The pain that makes you want to pop an aspirin is rooted in a traumatic engagement at the cellular level. For example, if you wake up from a nap with a headache because you slept wrong, the trauma releases prostaglandins, a type of eicosanoids, resulting in pain. Aspirin puts a stop to the pain by inhibiting cyclooxygenase, the enzyme that generates prostaglandins. With that the cellular inflammation decreases and the headache goes away.

The cycle of acute inflammation and the body’s anti-inflammatory response is how an injury gets healed and how we, as athletes, stimulate a response through hard training and ultimately get stronger and improve performance through recovery. Chronic inflammation, however, is considered a root cause for diseases as serious as diabetes and cancer.

For Sears, the role eicosanoids play in increasing or decreasing cellular inflammation was the target. And since certain fatty acids were the building blocks of eicosanoids, Sears sought to encourage production of good eicosanoids (anti-inflammatory, built with omega-3 fatty acids) against the bad eicosanoids (pro-inflammatory, built with omega-6 fatty acids). Sears envisioned that fish oil, loaded with omega-3s, could help produce a positive outcome in this equation. By eating fish or supplementing with fish oil, he reasoned, a person can increase the amount of good fatty acid intake and increase the amount of production of good eicosanoids, and thus fortify the body’s anti-inflammatory responses. Initial results showed Sears he was on the right track in his quest to control inflammation, but ultimately Sears’ research pointed to diet.

Sears recounted the story for me. “In 1988,” he said, “while I was working with the Stanford swim team coaches Richard Quick and Skip Kenney, we were getting good results with the fatty acid intake experiments in Japan, but when they returned to the United States their performance was crap. The thing that had changed was their diet: In the U.S. they were eating dorm food. I went into the bowels of the MIT library and found the data that showed us what was going on: If you have high levels of insulin, you’ll drive the anti-inflammatory eicosanoids into becoming inflammatory. So unless I controlled the diet I would not be able to control inflammation.” Sears said that it was in the following year that he developed the specific 40-30-30 diet necessary to complement the power of omega-3 fatty acids. It was a diet that sparked an ideal hormonal response to food—one that released a combination of insulin, a hormone stimulated by carbohydrates, and glucagon, a hormone stimulated by protein—to a neutral conclusion.

Sears conducted his initial tests on a range of athletes, from the Stanford swimmers to the Pittsburgh Steelers (under Sears’ nutritional supervision, Stanford swimmers won eight gold medals in the 1992 Barcelona Olympics). Throughout the past 20 years, Sears has since campaigned hard on the dangers of a high-carbohydrate diet, making the case that scarfing too much sugar, particularly from processed foods and grains, leads to chronically high levels of blood sugar and weight gain—precursors to adult-onset diabetes and obesity.

When Sears’ books started coming out in 1995, he was crucified because high-carbohydrate diets (generally recommending 10 percent of calories coming from fats, 15 percent from protein and 75 percent from carbs) still had a hold on the sports nutrition community and, as a matter of fact, the medical community, from the American Heart Association to the U.S. Surgeon General to the makers of the Food Guide Pyramid. They collectively trumpeted that to fight obesity you had to minimize or eradicate fat from the diet.

But Sears argued that a high-carb/low-fat diet left you feeling unsatiated and lethargic. Pigg’s anecdote about eating a stack of pancakes and finding himself both tired and hungry is an example of what Sears said was the body’s hormonal system working against you.

But Sears wasn’t given much of a chance to present his case. Since the medical establishment was so firmly entrenched in the idea of a high-carb/low-fat/low-protein diet, mainstream journalists were armed with quotes and documentation to paint Sears as a greedy snake oil salesman, as Jessica Seigel did in a 1997 story for Los Angeles Magazine. “Sears claims that his diet, which calls for roughly twice the fat and protein recommended by the USDA, regulates the body’s supply of insulin,” she wrote. “According to Sears, reducing levels of this crucial hormone makes the body burn fat faster and eliminates destructive food cravings. Medical research, though, has not linked insulin levels to weight gain in healthy people, and increasingly confirms that eating fat makes people fatter.”

That was then.

In the past decade a growing number of voices in the medical community have begun to support what Sears has been saying all along. One, that weight gain or loss is not simply a matter of calories in versus calories out, and that how food affects our hormones can have huge consequences on health and, ultimately, the economy of our nation.

This may have started on July 7, 2002, when the New York Times published an article, “What if It’s All Been a Big Fat Lie?” by nutrition journalist Gary Taubes. “If the members of the American medical establishment were to have a collective find-yourself-standing-naked-in-Times-Square-type nightmare, this might be it. … They find that their very own dietary recommendations—eat less fat and more carbohydrates—are the cause of the rampaging epidemic of obesity in America.” In the story, Taubes reported how a “subtle shift” had been taking place and established researchers based in places like the Harvard School of Public Health were having to acknowledge that despite lower cholesterol levels and a decline in smoking, heart disease had not declined with them. “That is very disconcerting,” Walter Willett, the chairman of the department of nutrition at the Harvard School of Public Health, told Taubes. “It suggests something bad is happening.” Taubes detailed how a hypothesis was growing that a high-carb, fat-free diet was “counter-productive,” making people “hungrier and then heavier.” The epidemic rages on: A study conducted at Johns Hopkins and published this summer suggested that if current trends continue, 86 percent of the American population will register as obese in the year 2030. And they will all be more prone to Type-2 diabetes, a situation that Sears has predicted will ravage the U.S. economy.

My personal experience with a high-carb, low-fat diet—my six months eating a vegan diet in which I paid little attention to the amount of protein and fat I was taking in—produced unwanted results. Despite running 50 miles a week at the time, a blood workup showed signs that I was becoming dangerously insulin-resistant. Or, in other words, pre-diabetic. Because my diet was constantly prompting a spike in insulin levels—insulin being a hormone that prompts the body to either use glucose for energy or store excess glucose in the liver and muscles—I was exhausting the system and a backlog of glucose was piling up in my blood, further taxing my hormonal system and creating a state known as hyperinsulinemia. Since it’s when insulin levels go down that the body starts tapping into stored body fat as energy, I had also enabled a fat-trapping mechanism within and I was recording a weight much higher than I should have been.

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