The author's weight changed little over the six diets, but his mood, energy, and key blood numbers varied considerably.     Photo: Shana Novak
Not all that long ago, the Paleo diet seemed like little more than a beefed-up fad diet—South Beach for the mountain time zone. Then CrossFit happened. South Beach dieters started doing deadlifts, and Paleo was the most-Googled diet in all of 2013. Even the New Yorker decided to weigh in on the trend last month.
I am not a fan. Almost six years ago, I wrote a story for Outside about a year I spent experimenting with different diets—two months each on six different plans, with regular blood tests and body-composition analysis throughout. I cheated a bit here and there; this was done not with an eye toward losing weight (I was competitive-cyclist skinny) but in hopes of finding a healthier way to eat that I could stick with. 
Paleo was among the diets I tried, and it left me feeling like crap. Here’s the thing, though: My conclusion at the end of the story might be the smartest bit of advice I’ve ever written. Much has changed since then. I left Outside, went to work atWired, got divorced, got remarried, and moved from Santa Fe to Boulder to San Francisco back to Boulder. Through all of that, I’ve never weighed less than 154 or more than 160. And at a physical last year, my doctor said my blood report was “suitable for framing.”
My diet looks pretty much like the Mediterranean diet filtered through the experiments I lay out at the end of the story: Kale-and-berry smoothies for breakfast (occasionally swapped out for a spinach omelet with bread dipped in olive oil); veggie-and-turkey wrap sandwiches or salads for most lunches; pastas, salads, fish for dinner; no dairy; few nightshades; very little red meat (and only grass-fed and/or game meat when I do); a lot of almonds and almond butter; liberal use of olive oil. And once every week to 10 days, I eat whatever the hell I want.
So here again—six years later but showing no signs of age—is the way I eat and how I got there.
“But you're so thin.” I got some version of that every time I told someone I was going to spend a full year subjecting myself to half a dozen diets. They were right. It was August 2008, the end of an intense season of bike racing, and at five foot eleven and 149 pounds, I'd crossed over into scrawny. But while pointing out the obvious, the Olsen-twin jokes and rib pokes revealed something more important: the assumption that, vegetarians and locavores aside, people change the way they eat only when they need to lose weight.
If you're thin, the thinking goes, your diet is fine. Of course, thin doesn't necessarily equal healthy. Not even when, for guys like me, it's the result of an athletic lifestyle. The reality is, many of us use our fast 10K times to excuse horrible food choices. I once saw an interviewer ask Robin Williams what he ate to keep his weight down, to which the famously bike-obsessed comic replied, "I can eat pretty much anything. I ride bikes." That's a popular attitude; sometimes the main appeal of a long ride is the beer-and-burger mayhem that follows. This may explain why a federal government survey released last summer found that heavy drinkers actually exercise more than abstainers.
At 38, with a family history of heart disease and a personal history of late-night pizza and uneven energy levels, I needed a better way. I wanted a strategy that would generate healthier eating habits without mandating strict adherence to an austere, dogmatic program. But where to start? The diet industry focused almost exclusively on overweight people for whom brisk hikes would be an improvement; there were few options for a trim, year-round athlete.
So I decided on a radical experiment. I would spend eight weeks each on six different plans representing the various options for would-be dieters, from popular fads to clinical studies: the Abs Diet, the Paleo Diet for Athletes, the Mediterranean Prescription, the Okinawa Program, the advice of a personal nutritionist, and the USDA's nutritional pyramid. I'd record every meal, snack, caloric drink, and workout, along with notes on how I was feeling, and make bimonthly visits to my doctor and the blood lab for weigh-ins, cholesterol checks, and body-composition analysis. I'd grant myself only two breaks: 19 days for my honeymoon, after the Abs Diet, and 11 days around Christmas and New Year's, after the Paleo Diet for Athletes. Huge pain in the ass. Huge.
My hypothesis: By applying the same discipline to nutrition that I apply to cycling, I'd be able to measure these diets against the claims of their authors. Each one would have something to teach me; each would also fail me. And along the way, I became the world's leading expert on how I'm supposed to eat.
As our ancestors diverged around the globe, nutritionist Laurent Bannock says, their systems developed to thrive on the foods at hand.   Photo: Shana Novak

The Abs Diet

Weeks 1 to 8
Creators: David Zinczenko and Ted Spiker
The Hook: If you've got a six-pack, you're probably healthy.
The Diet: Lots of protein and good fats, no refined carbs. Accompanying workouts blast those abs!
No. 1 Lesson Learned: Healthful meals can be tasty and easy to make.
Zinczenko is the editor-in-chief of Men's Health and the guy behind the bestsellingEat This, Not That! books. Where some diet authors wrap serious packaging around bubble-gum advice, Zinczenko has found success putting bubble-gum packaging around smart service. His strategy here is whole foods and a schedule of three small meals and three robust snacks per day. Follow the guide, Zinczenko says, and you'll lose weight without losing your mind. And thanks to lots of protein, plus the included workout plan, you'll emerge faster, stronger, and more swimsuit friendly.
I had a basic shopping list: peanut butter, chicken breasts, whole-grain bread, tomato sauce, spinach, milk, eggs, and recipes that rarely required more than 20 minutes. Plus, most breakfasts were smoothies and most lunch and dinner recipes provided extra servings I could freeze or refrigerate. This diet destroys any arguments about how eating well is too time-consuming.
One big takeaway: snacks are best used to prevent hunger, rather than to address it. A handful of nuts, a slice of melon, or peanut-butter toast a couple of hours after each meal kept my energy levels even throughout the day. Whenever I worked out, I was adequately fueled.

The Paleo Diet for Athletes

Weeks 9 to 16
Creators: Loren Cordain and Joe Friel
The Hook: The author of The Paleo Diet (eat like our Stone Age ancestors) teams with endurance-sports coach Joe Friel to tailor it for active types.
The Diet: Lots of game meats, raw produce, no refined anything except during endurance sports, then bars, bagels, gels, etc.
No. 1 Lesson Learned: It's tough to exercise when you're hungry all the time.
I understand now why Atkins adherents are so passionate about their meat-heavy lifestyles. I lost six pounds on this plan, and my body-fat percentage went from six to five. I also understand why Atkins defenders get so cranky: I spent all but the last two weeks of this diet feeling seriously underfueled, tired, spacey, and hungry.
What I did eat was delicious: elk, buffalo, salmon. But the recipes require a fairly knowledgeable hand in the kitchen and a stomach for organ meat. (I skipped the heart, tongue, and testicles.) And unless I was exercising, I wasn't allowed much in the way of carbs. I grew so tired of the approach that boredom or upset stomachs would end meals before I had eaten enough. I found myself looking forward to exercise because I could use it to excuse a granola bar.
Co-author Joe Friel admits to feeling weak during his first two weeks on the diet but says he started coming around by week three. It took me three times as long to feel somewhat normal. Halfway through, I broke down and bought an egg-cheese-and-potato-laden breakfast burrito, writing in my food diary, "Woke up with a hunger way beyond what the fruit and vegetables in my house could cover."
Still, my ratio of good cholesterol to bad cholesterol—possibly more important than your total number— was close to the best I recorded all year. There's definitely something to this approach. But as an active guy who's not looking to lose weight, there's just no way I'm going to stick to a plan that leaves me hungry and tired all the time.

The Mediterranean Prescription

Weeks 17 to 24
Creators: Angelo Acquista with Laurie Anne Vandermole
The Hook: More and better years by eating like a Sicilian.
The Diet: Fresh produce, legumes, nuts, whole grains, fish, olive oil, and red wine.
No. 1 Lesson Learned: Healthy eating means moderation of everything more than elimination of anything.
This one will be a fallback for the rest of my life. The soul of the plan is the fish-and-produce-rich diet of Sicily and neighboring Mediterranean culture swordfish with capers, pasta fagioli, poached pears in Chianti. Even as a lazy and inexperienced cook, I found the recipes easy. As an endurance athlete, well, pasta's been the staple fuel source for runners and cyclists for decades; I felt good and crushed it on the bike.
This all makes sense. A recent study by Australian researchers comparing the moods of low-carb dieters to low-fat dieters found that the latter reported much better emotional states after a year of dieting than their low-carb counterparts.The Mediterranean Prescription was a pleasant and forceful reminder that the evils refined carbs have done to Americans' health are no reason to jettison carbs altogether. By all means, get white bread out of your life, but don't feel bad about reaching for a piece of whole-grain goodness. And dip it in some olive oil. That's become a regular weapon in my afternoon-snack arsenal.
I also love the fact that, in a book that's ostensibly about weight loss, Acquista's only real discussion about calories is to say that counting them will ultimately derail attempts to lead a healthier lifestyle. The core message: Eat as many vegetables as you can, plus healthier versions of most of the foods you already like, and find activities you enjoy. But don't forget that sometimes health and happiness depend on big, festive meals and afternoon naps. If your pants get tight, eat less and exercise more. I can get behind that.
Acquista's only real discussion of calories is to say that counting them will derail attempts to lead a healthier lifestyle.   Photo: Image Source/Corbis

The Okinawa Program

Weeks 25 to 32
Creators: Bradley J. Willcox, D. Craig Willcox, and Makoto Suzuki
The Hook: Eating like the longest-lived people on earth.
The Diet: Largely plant-based, but with chicken, fish, and unrefined carbohydrates. And lots of soy products.
No. 1 Lesson Learned: Conventional wisdom about what constitutes a healthy diet can steer you wrong.
The authors of this book are scientists and clinicians who conducted years of research on the Okinawans and their eating habits, a slightly altered version of the familiar Japanese diet. I lived in Japan between the ages of 25 and 31 and left enamored of the food. I expected good things from this plan.
What I came away with was proof that you can follow a diet that almost everyone believes to be beneficial and still be one teriyaki chicken breast away from a heart attack. I felt healthy, had energy, and enjoyed every meal, but my total cholesterol shot up 43 points, my HDL (good) cholesterol dropped, and my body fat increased. My doctor warned that if my next diet didn't bring my cholesterol under control, she would recommend medical intervention.
So what happened? The soy? Maybe. There is a growing body of research, summarized in the book The Whole Soy Story, suggesting that consuming excessive amounts of soy products can pose health risks, including disrupted hormone levels. I'll point out again that I conducted a one-person, self-guided study ripe for sophistic misinterpretation. But based on what I learned from my next diet, I'm guessing that while the Okinawa Program might do wonders for Okinawans, who spent thousands of years eating this way, I'm better off eating like they do in Western Europe, where my ancestors are from.

Nutritionist

Weeks 33 to 40
Creator: Laurent Bannock 
The Hook: A customized diet based primarily on ancestry.
The Diet: A familiar balance of protein, fats, and carbs, but from a detailed food list tailored to your DNA.
No. 1 Lesson Learned: Each of us can find a diet that works. And it's awesome.
You can't beat having a nutritionist prescribe foods that your genes have equipped you for. If my own experience is telling, your blood profiles will improve, your body will get leaner, you'll sleep more soundly, and you'll enjoy consistently high energy levels throughout the day. That was the case when I tried this plan two years ago, and I got the same results when trying it again for this project.
Bannock has spent years refining diet strategies based on ethnicity. As our ancestors diverged around the globe, he says, their systems developed to thrive on the foods at hand. Bannock makes specific adjustments for individual circumstances: weight, allergies, activity level, etc. But for the most part, if you're of East Asian descent, your diet will look a lot like the Okinawa Program. And if you share my Irish heritage, Bannock will tell you to eliminate or dial back on, among other things, chicken, tomatoes, coffee, soy products, and all dairy.
The biggest drawback: eating out. With such a long list of banned foods, it's almost impossible to find anything in a restaurant. Thankfully, Bannock is a proponent of occasional cheating.

MyPyramid.gov

Weeks 41 to 48
Creator: USDA
The Hook: A free, interactive Web site that helps you meet individualized nutrition targets.
The Diet: The oft-maligned USDA Food Pyramid.
No. 1 Lesson Learned: The more diet data you record, the more you'll learn.
I wanted to finish with something more self-guided, and the Department of Agriculture's MyPyramid.gov site exceeded my expectations with three interactive tools that, used together, come close to being a free nutritionist. The tools use age, weight, height, and activity levels to create a daily caloric target, then tell you how much you should eat from each of the five main food groups (grains, vegetables, fruits, dairy, and meat and beans). Input what you've eaten and how much you've exercised, and graphs show where you are relative to your targets.
Problem is, I don't trust all of the targets. The USDA has to please a lot of people: medical associations, government panels, even farm lobbies. The calorie numbers seemed about right, but other food recommendations were suspect. I can't see how anyone who didn't have to answer to dairy farmers would recommend three or more cups of milk per day. (All it took was a few minutes with me in an enclosed space during this diet to understand that this was bad for my system.)
The site does one important thing very well, however: It forces you to pay attention to everything you eat. You realize quickly how hard it is to get in sufficient produce and how quickly calories, fats, sodium, and cholesterol add up. This site would no doubt be an improvement for some. But by this point the generalized guidelines felt like a step backwards.

Conclusions

What did I learn in the end? Lean protein, good fats, healthy carbs. More specifically: modestly sized meals consisting of lots of produce, a bit of lean meat now and then, and grains that haven't been bleached and pulverized into submission. Also, olive oil is good, and snack on nuts and dates.
In broad strokes, that approach works for almost anybody. But broad strokes don't cut it. I also discovered that wheat doesn't cause me problems, that dairy does, and that I should avoid tomatoes. You might be totally different. The Okinawa Program may save your life. The Paleo Diet for Athletes could make you faster. I can't say how you'll react to any single diet.
What I can provide, though, after 12 months alone in the diet-industry wilderness, is a strategy for finding what does work for you— my own take on what is commonly referred to as an elimination diet. You'll have to keep a diary of everything you eat and how it makes you feel, but it won't take a full year— more like two months.
The first two weeks will be the hardest. Eliminate prepared foods, coffee, dairy, nightshades, wheat, soy, alcohol, corn, eggs, processed grains, processed anything else, added sugar, and all but the most organic, free-range, grass-fed of meats. Relax—this leaves you with a lot of options. You'll find most of them in the produce section. Mix in the occasional serving of fish, turkey, or buffalo, drink herbal tea, discover spelt bread, and learn to cook quinoa. You'll get through.
After that, start methodically experimenting, one at a time, with foods you eliminated and see what happens over the next 72 hours. Did that omelet make you feel nauseated? Any skin issues after tomatoes? Did meat make you feel better? You see where this is going. After two months, you'll have a functioning idea of foods that work for you and ones that work against you. If you can, see your doctor and ask for blood tests at the beginning and end of your two months.
A last bit of advice: Once you've settled on a nutritional approach, cheat. Every now and then, eat whatever you want and wash it down with what's on tap. Knowing you can do this will make it easier to eat well the rest of the time.
That's it. It may not be completely scientific, but I bet it's closer than anything you've tried. I also bet it will work.

The Shape of My Life

How certain foods make you feel and what's actually happening to your body don't always match up. Here, my key numbers before and after each diet. (Click to enlarge.)