Inside Dr. Barry Sears’ Zone Diet

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

Even though Olympic gold medalist swimmers and one of the best triathletes in the world adopted the diet he recommends in the early 1990s, Dr. Barry Sears was cast in the mainstream as a radical and a charlatan in the nutrition world. But has he been right all along?

This story was originally published in the November/December, 2011, issue of Inside Triathlon magazine. It has been edited for web publication.

“He did not live on nuts and berries; if the furnace was hot enough, anything would burn, even Big Macs.” — “Once A Runner” by John L. Parker, Jr.

This line from my favorite work of running fiction pretty much summed up my nutritional philosophy for 15 years. I trained for everything from the 1500 meters on the track to the Ironman triathlon, and as a disciple of the high-mileage creed I pounded out 20-mile long runs even when training for the shorter-than-1-mile foot race. At peak mileage I did what triathlon legend Scott Molina used to do: two long runs per week.

The payoffs were two by my reckoning: One, I got fit as hell and two, I felt I could eat anything and everything I wanted. Looking back though, and having learned what I’ve learned the hard way in the past two years, I have to wonder: If I hadn’t treated my diet as such a nonissue would I have been faster?

“You cannot dissociate training from the diet,” said author Barry Sears, Ph.D., one of the world’s leading authorities—if not the leading authority—on hormonal response to food intake. “The two are coupled at the genetic and molecular level.”

My introduction to Sears was back in 1995 when his first (of many) books on the Zone diet hit the shelves and became a bestseller. In “The Zone,” Sears claimed that by adhering to a diet consisting of 40 percent carbohydrates, 30 percent protein and 30 percent fat, a practitioner would reap the following benefits: permanent weight loss, prevention of disease, enhanced mental productivity and peak athletic performance. Within the book Sears argued that a 40-30-30 diet, high in omega-3s, would stabilize the hormonal response to food and shift into gear a fat-burning metabolism. I recall vividly the outcry of the sports nutrition world—his book a heresy, swiftly labeled as being a high-fat, high-protein, low-carb diet that would harm rather than help. Based on the reaction of the dietitians and scientists to the Zone topic I witnessed at a sports science conference in Vancouver, British Columbia, in June of 1996—I was there as a reporter—I never cracked open the spine of a Zone book and quickly dismissed Sears as another want-to-be diet guru. Besides, I was still operating on the “if the furnace is hot enough” nutrition plan.

But three years ago my body staged a strike to a dramatic effect: In addition to limping along with 15-watt-bulb levels of energy, and increasingly aware that I was being gripped by depression (and perhaps it was already so), a sequence of physiological breakdowns occurred, including my back going out for weeks at a time and a failing right knee. Intuitively, without a doctor’s recommendation or advice from a friend, I knew my garbage diet was the problem. I then began trying a variety of things, from juice fasts to a completely vegan diet. Being vegan definitely helped me shed weight, but the low energy levels persisted, as did my injury problems, and I was losing my identity as a triathlete and runner.

In a parallel way, I was following a path once blazed by triathlon legend Mike Pigg.

“I was eating like an 18-year-old, just a complete garbage hound,” Mike Pigg told me over the phone recently. I’d asked him about the late 1980s, years when the Californian known for being the hardest working triathlete in the world struggled to nail a breakthrough at the Hawaii Ironman. “In 1989 everything was going downhill.” Pigg was plagued by diarrhea and a weak stomach, and he experienced a moment of enlightenment when he noticed how he felt after eating his customary stack of six pancakes before getting ready for a bike ride. “I felt both sleepy and hungry,” he said, the exact opposite of his intent. “This turned out to be one of the most important lessons I have learned in life. Ask yourself how you feel after you eat a meal. Does a meal make you feel stronger or weaker?” When Pigg began to listen to his body, he altered his diet so that it had more protein and healthy fats. He ditched processed sugar and reached for more fruits and vegetables. “I realized that carbs and protein were the ticket. And I’m happy to eat the good fats—avocados, butter and olive oil.” A favorite dish of his became steak, potatoes and avocado.

“I made the changes to my diet and was able to extend my career as a pro for another 10 years,” he said. Pigg remains a formidable athlete to this day, recently having earned, through a sub-eight-hour ride, the coveted belt buckle at the Leadville 100 mountain bike race.

The diet that Pigg says helped salvage his life as an athlete was in sync with the essential parameters of the Zone diet that Sears, a former staff scientist at the Massachusetts Institute of Technology, was still developing in 1989. Sears was working to answer the question: What’s the impact of food on the hormonal system and how does this affect a person’s health?

Unlike Pigg, Sears wasn’t pressured to salvage a career as a pro athlete—he was considerably more motivated by personal reasons. His father died at the age of 53 from a heart attack, as did three uncles, also in their early 50s. A biochemist with expertise in genetic expression, cancer delivery systems and the molecular mechanics of hormones, Sears knew that this was more than a coincidence. “I’m a walking genetic time bomb,” he once wrote. Sears began thinking about food at a biochemical level and developed the belief that when it comes to the expression, or non-expression, of our genes, the impact of food on the human hormonal system made food an incredibly potent drug.

“If you write one thing from this interview,” Pigg said, “Tell the readers this: Listen to what your body tells you after you eat a meal.” In Sears’ books, he says the same thing, indicating that messages, like the ones Pigg described, are hormonally driven at the molecular level, for powerful reasons, and he gives readers instructions on how to adapt meals to what is sensed—“Do you feel tired? Do you feel hungry? Do you feel full?”

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