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Sticking It to Diets: An Interview with Matt Fitzgerald

In his new book Diet Cults, Matt Fitzgerald argues against the idea that there is any one "best" way to eat. Along the way, he covers popular diets such as Atkins, the raw-food movement, and the Paleo Diet, each time exploring the dangers of excluding an entire food group. By the end of the book, Fitzgerald replaces the dogma of dieting with a proposal he calls "agnostic healthy eating." In time for the release of his new book, we caught up with Fitzgerald to discuss what belongs on the modern athlete's plate. 

OUTSIDE: What led you to write Diet Cults?
FITZGERALD: Mainstream science is on one side, saying there’s no single ideal diet for humans. But all around us, popular diets are claiming that they are the healthiest diet for all. It’s a fundamental contradiction. My gut instinct was that it was not rational to say any one diet is the best way to eat. I wanted to offer an alternative.

Why are people so passionate about diets?
Food is such a basic symbol of identity. We become emotionally invested. Even three-month-old infants show dislike for puppets who don’t like the food they like. I think we are all susceptible to the mythology that one diet is best.

Have you ever fallen for a diet cult?
Maybe supplements in some cases. I am becoming much more skeptical toward initial positive research on supplements, because if you wait long enough, some negative research comes out too.

In your book, you propose we embrace agnostic healthy eating. How do people eat like this?
They don’t demonize any nutrients. No entire food categories are eliminated. They have fruits and vegetables with almost every meal. There aren’t a lot of fried foods or sweets. It’s pretty basic stuff, but can fuel the best athletes and weekend warriors like us. 

Do a lot of people already embrace agnostic healthy eating?
The silent majority of health conscious eaters out there want to eat healthy and are turned off by diet cults. In my exposure to world-class endurance athletes, very few Olympic-caliber athletes do any kind of diet with a name. They don’t demonize any nutrient. My personal instinct is that I don’t want to trust fear mongering salesmen who vilify a lot of the food people eat.

So elite endurance athletes are less likely to embrace diet cults. What about recreational athletes?
My perception is that amateur athletes are quite a bit more likely to go for diet cults. I have two theories on this. One is the sour grapes theory: That when competitive people find they can’t win races, the point of the sport switches from winning to doing it correctly. Barefoot running, Crossfit Endurance, and a lot of diets fall into that. Athletes who can win races don’t want to mess with the formula that works because a lot is at stake. The other part of it is that in today’s world, it can be hard to eat healthy. You have to swim against the stream. The diet cult does the work of how to eat healthy for you.

{%{"quote":"“The [Paleo Diet] doctrine is absurd. It is a fantasy.”"}%}

Diet cults tend to be trendy. That happened with the Atkins diet a decade ago, and the Paleo Diet in recent years. Are all diet cults destined to fade away eventually?
In the broader context, I believe diet cults have always been with us and always be. The Kosher eating of the Jews is a diet cult. The pleasure eating of the Food Network shows is an ongoing phenomenon. Vegetarianism has ancient pedigree. I’d guess some version of Paleo will persist because there’s something so fundamental in the idea of going back to our early paradise.

You devote a section in your book to the Paleo Diet. What’s your take on it?
The doctrine is absurd. It is a fantasy. The diet is based on a 19th-century misunderstanding that evolutionary adaptation moves at a glacial pace. The Paleo idea that no animal should eat anything it hasn’t eaten before is silly. There was the moment when chimps leapt out of trees and had to adapt their diet. Radical changes came. We started eating meat, cooking food, and traveling all over the planet. There’s also epigenetic adaptation, where genes you already have are switched on and off. Diet adaptation can happen very quickly. As for whether the diet is healthy: It can be very healthy, but the way a lot of people do it, with indiscriminate heavy meat eating, is not very healthy. I think people should eat a lot more fish and high quality meat. I see a lot of Paleo followers gobbling huge amounts of bacon. 

Another chapter in your book talks about the controversy over hydrating with sugary sports drinks. What do you think about this?
People have this premise that sugar and carbs are always bad and try to explain away 50 years of research. You don’t want a lot of sugar in your diet when you aren’t exercising, but sugar is a performance enhancer. When you’re exercising, you want the fastest fuel you can get, and sugar is the highest octane stuff. I’m a big believer in fueling for performance.

A number of athletes have tried low-carb approaches in recent years. Is this diet cult effective?
If there’s any nutrient an athlete should go out of their way for, it’s carbohydrates. We know athletes in heavy training on high-carb diets are better able to absorb that training. Very few Olympic-caliber athletes mess around with this.

What about all the people who don’t care about athletic performance, but just want a diet that helps them lose weight?
I call it the suck-it-up diet. The secret to successful weight loss is motivation. Get out of the mindset of finding one way that works, and realize a lot of ways work. You still have to choose something specific. Anyone who loses weight and keeps it off doesn’t just wing it. They have rules and stick to them, but they’re not necessarily the specific rules of a diet cult.

How would you rate your own diet?
It’s much better than average. My diet looks pretty normal, but is high quality on two levels. The first is that it’s weighed heavily toward the highest quality food types, such as fruits and vegetables. I have very few fried foods and sweets, and not a lot of refined grains. I eat more fish than any other kind of meat. It’s also quality in that I buy high quality food, such as organic food, and grass fed beef, and try to pay a lot of attention to ingredient quality. But I still have at least one beer a day. My wife and I like to eat out. We celebrated my birthday on Saturday and I had French fries at a restaurant, and I almost never eat them.

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Performance-Enhanced and Sex-Driven

Probiotics are back (yes, they were once a thing) and a growing number of companies claim that by adding live microorganisms, bacteria does the body good. Dannon’s Activia yogurt touts probiotics as a way to regulate the digestive system. Powerful Yogurt and Naked Pizza serve up similar health claims. The brisk business in beneficial bacteria brings in around $28 billion a year. With names like Lactobaccili, Streptococci, and Bifidobacteria, these microorganisms have been linked to lower rates of constipation, ulcerative colitis, and chronic diarrhea. Consult with Dr. Google and you might find that probiotics are the next Prozac, the cure for acne, and a surefire boost to your sex appeal.

Despite nearly a century of research—first on “scientifically soured milk” and life-prolonging yogurts—the concept remains largely under-researched and oversold. At the same time, scientists are finding that the trillions of microorganisms, as many as 10,000 different species, or about 160 species per person, flourish in our warm, wet intestines. Microbes influence our health, sometimes far beyond the gut itself. If the human microbiota, as it’s known, is an integral part of overall health and physical fitness, could microbes serve as performance-enhancing microorganisms?

One study—known, in some circles, as the “Great Balls of Fire”—claimed that probiotic yogurt imbued male mice with bigger balls and a behavior the researchers called swagger. The lead investigator, Susan Erdman, a cancer biologist at MIT in Cambridge, Mass, is a researcher with an unflagging enthusiasm for her work (and also a dedicated athlete). Three years ago, quite by chance, she told me, a colleague had noticed that the female mice in her lab colony were becoming so unbelievably shiny, they looked almost opalescent.

“I have dogs at home,” Erdman says. “Some of them go after the yogurt containers and lick them out when we’re done. I remember thinking, ‘Zappy is a black dog who glows like crazy.’” Back in the lab, colleagues began to notice that male mice had large, protruding testicles. (She showed one video of a mouse strutting around his cage like overeager stud at an oonts-oonts nightclub.) The animals exhibited slim physiques and had little abdominal fat. What gave them a youthful edge: yogurt.

Erdman suspects that bacteria confer a “glow of health” in aging animals, essentially mimicking the peak health of younger animals. In a series of recently published studies, she examined mice fed an isolated strain of bacteria called Lactobacillus reuteri, a microorganism originally isolated from human breast milk. Drinking the probiotic infusions halved a mouse’s body weight, no matter how much gooey “fast-food” chow they ate. The bacteria sped the healing of superficial skin wounds. In males, it led to heavier testes. “We ended up with a triad of features that we affectionately call shiny, skinny, and sexy,” she says. “These are indications of supreme physical fitness.”

{%{"quote":"“We should be able to harness probiotic microbes just as we’ve harnessed microbes to make our bread and brew our beer.”"}%}

Probiotic bacteria, which tend to number in the billions, don’t stick around with the tens of trillions of microorganisms already living in the gut. Yet, just passing through appears to shake things up and the ingested microbes stimulate the body’s immune cells, though the exact mechanism behind the effect remains unknown.

The strain Erdman studied, for example, ushered in a cascade of hormonal changes connected with an animal’s thyroid, adrenals, and gonads. “When we started feeding them microbes, the mice suddenly became more active,” she says. “How would that translate into people? You would presume that they would suddenly have more desire to get up and move around—increased energy levels, changes in metabolism, that’s mostly a good thing, right?”

So far, despite any speculation, there’s only tantalizing hints for how research in mice might translate into healthy humans. In one 2011 study in the New England Journal of Medicine, researchers examined 1.6 million years of data to determine what factors caused Americans to gain weight as we age. Potato chips, processed meats, and sugary drinks were the worst for lean body mass. People who ate yogurt, on average, lost about one pound every four years. Today, the U.S. National Institutes of Health lists hundreds of trials on probiotics—from dental health to weight loss—and most of the commercially available Lactobacilli and Bifidobacteria strains target gastrointestinal disorders.

If a particular active ingredient, or cocktails of organisms, treats diarrhea, then another set of organisms may better stave off post-marathon fatigue. (After all, you don’t grab any random pill when you’re sick.) Perhaps probiotics altering digestion also give athletes a boost by contributing to good overall health. In the few small studies thus far—hinting at longer run-to-exhaustion times and improved immune response of fatigued athletes—the existing concoctions do not appear to be a performance panacea. Moreover, because people may carry genes that make them more or less responsive to probiotics, physicians may need to get a sense of who you are as an individual before recommending a microbial cocktail that would be particularly good for bringing out the best you that you could be.

Today, there’s still a substantial gap between the lab incubator and your mouth. But looking around, you might never notice that. In the U.S., there’s no standard of labeling for probiotics. Marketing claims go largely unregulated. “If you go to your local pharmacy or supermarket, you will see shelves with compounds labelled as probiotics,” says Martin J. Blaser, a microbiologist at New York University and author of the book Missing Microbes. “Each of them has different claims for what they can do. They represent many different organisms. What I can say for sure is that almost none of them has been well tested—with respect to any of the claims.”

Not that scientists doubt the importance of these microorganisms. Far from it. Are the most important microbes may be the ones we evolved with for millions of years and acquire early in life? Blaser worries that we’re eradicating these species through the indiscriminate use of antibiotics. (Populations such as the Swedes, using far fewer antibiotics per capita, he says, are at least as healthy or healthier as we are.) Once we better know what’s missing, he says, we can expect to deliberately add them back in. “At some point in the future, we will have scientifically based, well-tested probiotics that will have specific uses to improve human health. We should be able to harness specific microbes to use them for our advantage just as we’ve harnessed microbes make our bread and brew our beer.”

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Showdown: Walmart vs. Whole Foods Organic Prices

In April, big box chain Walmart announced it would carry organic food products, claiming that its Wild Oats packaged goods will save customers “25 percent or more” compared to other national brand organic products.

Until now, most organic foods have cost more than non-organic foods because, as Wild Oats CEO Tom Casey told NPR, the “production and distribution of organic food is still highly fragmented,” meaning they are not done on a large enough scale to become cost effective. Walmart’s plans to sell more than 100 organic products at more than 4,000 stores across the U.S. should increase the efficiency of organic food production, thereby dropping costs.   

Consumer Reports put together a comparison of Wild Oats products and the best possible deals they could find at supermarkets around Yonkers, New York. We decided to see how Walmart’s prices measure up to the prices at popular organic grocer, Whole Foods. Check out the chart below to see what we found. 

(Interesting side note: Wild Oats started out in Boulder, Colorado in 1987.  Whole Foods bought Wild Oats in 2007 for $565 million, then was forced to sell the brand in 2009 because of antitrust concerns.)

Whole Foods prices reflect the lowest organic prices found at Whole Foods in Torrance, California, on May 5. Walmart prices were first reported by the Consumer Reports. Groceries prices can vary widely by state and city, making comparisons difficult.*


In most cases, Walmart’s organic offerings are significantly cheaper than those found at Whole Foods. If you think that has Whole Foods scared, though, think again. As Whole Foods CEO Walter Robb told CNBC, “Of all the customers in the market, their customers overlap the least with ours.”

*This paragraph was modified to clarify that we have not conducted a direct comparison and that prices vary widely across states. The chart has also been updated to reflect the lowest product prices from the Torrance, California, Whole Foods. An earlier version of this piece overstated the cost of four products found at the Torrance Whole Foods. 

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If You're Not Eating Enough You Might Gain Weight

Shannon Scott thought training for a distance triathlon would help her drop the few extra pounds she’d always hoped to shed.

Scott began working out for an hour and a half to two hours each day. When she didn’t lose weight, she cut back her daily calories to 900 a day. Still, she couldn’t get the scale to budge.

She signed up for Ironman Canada, adding even more volume to her training schedule each week. Aware of the physical demands on her body, she raised her daily caloric intake to 1,200 calories a day, but wouldn’t allow herself to eat any more than that. Each week of training, she gained another pound.

“It was so frustrating and counter intuitive,” Scott said.

Scott is just one of many athletes who start training for an endurance event with the expectation of losing weight. While some do indeed drop weight, others feel defeated as they watch the scale move in the opposite direction. On forums of endurance web sites such as, conversation threads show athletes expressing frustration over weight gain during training.

For Scott and other distance athletes, the pounds come on because they aren’t properly fueling their activities. The body then develops a defense mechanism against the perceived threat of starvation, causing athletes to retain or gain weight.

Dr. Emily Cooper, director and founder of Seattle Performance Medicine, sees Scott and many other patients who are perplexed because they’ve gained weight with endurance training. While some never had a weight problem before, far more have struggled with diets for years.

“It is super common in my practice to see people under-fueling exercise and gaining weight,” Cooper said.

Dr. Rick Kattouf, a trainer, author, and CEO of TeamKattouf Inc., also frequently works with athletes who find themselves gaining weight with endurance training. Many of them decided to prepare for a marathon as a way to lose weight, and fear increasing caloric intake with training volume. When examining their nutrition plans, Kattouf often finds they aren’t eating enough before, during, and after exercise.

“The body goes into preservation mode,” Kattouf said. “It’s very frustrating for the athlete because they feel like they’re training more than they ever have before, and their body composition is going in the opposite direction.”

The scientific process that happens with under-fueled sports activity works like this: A workout session increases ghrelin, a hunger hormone that jacks up the appetite, slows the metabolism, and tells the brain the body is hungry. Athletes can mitigate the production of ghrelin by eating before and during exercise.

At the same time that ghrelin rises, the hormone leptin drops. Leptin reassures the brain that body weight is not too low, so without enough, metabolism drops and the body tries to hold on to fat. Endurance training is known to suppress leptin, especially in women.

The rise in ghrelin and drop in leptin becomes pronounced when athletes don’t take in enough food to support their exercise. Sometimes, they’re consciously restricting calories, as was the case with Scott. At one point, she drank only protein shakes because she wanted to be sure she wasn’t consuming any extra calories.

In other situations, exercising without proper fuel is less intentional. Many busy athletes fit in their workouts in the early mornings, and don’t take the extra time to eat a meal beforehand and immediately after. According to Cooper, even if someone takes in sufficient calories throughout the day, they’ll still face hormonal problems if they fail to eat before and after training.

To avoid falling into this imbalance, Cooper suggests making meals around workouts a priority, and not an option. Since exercise endorphins suppress appetite in some people, anyone training for endurance events can’t rely on hunger alone.

“Athletes need to eat mechanically and not by appetite,” Cooper said.

Kattouf also recommends that his clients adjust their lifestyle to compensate for endurance training. He makes sure they aren’t over-training, balances distance workouts with strength sessions, and advises increases in food and sleep.

Some athletes can alter their nutrition and training plans and see immediate results, while others may need longer to recover. For Scott, the metabolic stress of severely under-fueling and overtraining for so long has forced her to back off all endurance exercise. By resting and eating more, she’s finally begun to lose weight, and her metabolic hormones are beginning to rebound to healthy levels. In the last several months, she’s lost 20 pounds.

Scott isn’t sure if her body will ever let her compete in Ironman distance events again, but for now, she’s happy to feel healthy.

“With or without the weight loss, my energy is amazing and I’m not exhausted,” Scott said. “That is priceless.”

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