Why Can't the Experts Agree on Which Diets Work?

Paleo, low-carb, vegan, low-cal? Will any of these diets help us lose weight?
Where's the research? What's the deal?

This is one in a series of articles. For more on this subject visit The Daily Meal Special Report: Is Our Food Killing Us? Diet, Nutrition, and Health in 21st Century America.

When Howard Helmer retired as the senior national representative for the American Egg Council in 2010, at the age of 72, after 42 years doing what he called “hustling eggs,” it was the end of the era. As a hungry young food writer in the early 1990s, the single best thing that could happen was lunch with Helmer: He had an extravagant expense account and excellent taste in restaurants, and was fabulous company; from his encyclopedic knowledge of Broadway musicals to his status as a two-time Guinness World Record holder (the world’s fastest omelette, in 39 seconds, and the most omelets ever made in 30 minutes: 427, which he admitted were “moist”) no topic was off limits. There was only one thing he wouldn’t discuss: “the cholesterol debacle,” as he called it, that dogged eggs. Helmer was referring to the fact that in the 1980s America’s leading nutritionists cited health studies that warned the country off eggs, associating them with tremendously increased risk of high blood pressure and heart disease. Although the idea had been debunked by the time I encountered Helmer, there were still some stubborn Americans — both clinicians and consumers — clinging to it.

And that’s what happens when doctors and scientists tell us what to eat and then, down the line, change their minds. Meanwhile, the crisis of obesity in America gets bigger, literally. In February, the bestselling nutrition, science, and health author Gary Taubes reported in The New York Times that obesity and its related diseases, especially Type 2 diabetes, cost the U.S. health care system more than $1 billion per day. So if, say, an egg is bad for you or not is detrimental: “It’s not hyperbolic to suggest that the health of the nation may depend on which is the correct answer” to these dilemmas of what to eat, Taubes asserted.

Along with the obesity rate in this country, the suggestions for overcoming it have also ballooned: In 1960, fewer than 13 percent of the American public was obese and fewer than 1,100 articles on the subject had been published; last year, more than 36 percent of the American public could be considered obese, and more than 44,000 articles were published on the topic. So the more and longer we hypothesize, the fatter we get.

While we’re contemplating our collective fatness, we wander the aisles of our local Piggly Wiggly in hopes of figuring out a plan for dinner. These are a few of the trendy dietary choices you have as an American head of household concerned about her or his weight:  

You could go Paleo and follow the so-called “cave man” diet based on the eating patterns of our Paleolithic ancestors as popularized by the folks who do Cross Fit and post selfies of pulling tractor tires across gym parking lots. This diet advocates eating lots of lean protein, “alternative fats” like coconut and macadamia nut oil, and all the vegetables you can manage — but no dairy, wheat, or sugar (including the natural kind found in most fruits).

You could go low-fat as the U.S. Department of Agriculture suggests with its carb-heavy food pyramid in a plan that rode a considerable wave of popularity throughout the 1990s and is still touted by groups including the National Heart Lung and Blood Institute. Do this and you'd buy foods like light mayonnaise, diet soda, fat-free yogurt, low-fat microwave popcorn, and skim milk.

You could go vegan and observe an animal-product-free diet (no meat, no dairy).  Initially touted by hippies and yogis and now embraced by celebrities from Alec Baldwin to Ozzy Osbourne (we’ll give Ozzy credit even though he barely lasted “more than a week or two”), this diet is big on foods like brown rice, black beans, lentil soup, and veggie burgers topped with vegan tofu-based cheese (no eggs, though).

You could go straight-up low-calorie and buy a full complement of Lean Cuisine entrées (Lean Cuisine is owned by Nestlé, the self-described “World’s Leading Nutrition, Health, and Wellness company”) for three meals a day, including a Canadian bacon English muffin for breakfast (180 calories, 650 milligrams of sodium, 27 grams of carbohydrates), a chicken club panini for lunch (360 calories, 675 milligrams of sodium, 45 grams of carbohydrates), and an enchilada rojo with Mexican-style rice for dinner (310 calories, 670 milligrams of sodium, 46 grams of carbohydrates).

And you could be wrong about each and every one of those decisions, depending on the source you cite:

No paleo: According to the book Paleofantasy by University of California-Riverside biologist Marlene Zuk, since the Paleolithic period occurred between 2.5 million and 10,000 years ago when running down a bison until either he or you dropped was the norm, following such a diet ignores the fact that the plants the cavemen ate also evolved and they have very little in common with what grows in the ground today. Or as the science journalist Ferris Jabr put it last year in Scientific American:

“The Paleo diet not only misunderstands how our own species, the organisms inside our bodies and the animals and plants we eat have evolved over the last 10,000 years, it also ignores much of the evidence about our ancestors' health during their — often brief — individual life spans (even if a minority of our Paleo ancestors made it into their 40s or beyond, many children likely died before age 15).”

No low-fat: In a recent and groundbreaking release of information, researchers at the Harvard School of Public Health report that the low-fat diet not only failed to significantly improve the cardiovascular health of the nearly 49,000 women who participated in the just-completed eight-year Women’s Health Initiative Dietary Modification Trial, but it also didn’t help them lose weight.

No vegan: According to Dr. Mark Hyman, co-medical director of Canyon Ranch Spa, author of the best-selling diet book The Blood Sugar Solution, and close personal friend and dietary adviser of Bill and Hilary Clinton, “It’s hard being a vegan to eat enough good, quality protein and not have too much starch…I know a lot of fat vegans.”

No low-cal meals: The value of reducing calories is not controversial, but eating low-cal frozen meals to do so is: The USDA says healthy Americans require no more than 1,500 milligrams of sodium per day, and that sample Lean Cuisine menu would leave us with 1,995. Products like Lean Cuisines also tend to be low in dietary fiber, high in preservatives, and are by no means considered “whole foods.”

So what does this mean to me in my Piggly Wiggly: How can seemingly reputable doctors and researchers offer such conflicting information about the merits or demerits of every other diet ever conceived?

Science writer Gary Taubes, author of books with such titles as Good Calories, Bad Calories: Fats, Carbs, and the Controversial Science of Diet and Health and Why We Get Fat: And What To Do About It, asserts that it’s exceedingly difficult to fund a long-term, comprehensive dietary study that tracks eating habits over a lifetime, is rigorously monitored, and that involves convincing thousands of people to permanently change what and how they eat for years if not decades. For potential study participants, more than weight gain is at stake: People could die of heart attack, cancer, or stroke (all that sodium!) while solutions are determined. And somebody has to fund the whole thing, too. As Taubes points out, part of the reason the low-fat diet trend was so readily embraced had to do with the fact that scientists never performed a comprehensive clinical trial of the relationship between dietary fat and cardiovascular disease because it would have been too expensive. Regardless, all of these discrepancies make you want to gather up as many nutritionists as you can (maybe in a giant shopping mall’s food court) and bellow: MAKE UP YOUR MINDS, ALREADY!

I think about Howard Helmer’s quest to convince Americans to stop fearing eggs by embracing tactical marketing: Sourcing food writers and editors, like me, who liked to be entertained and asking them to include as many eggs as possible in their articles and recipes. It worked for Helmer. But the only thing that’s working for the American people today is our scales; they go up and up while we try to figure out what we’re supposed to eat. Walter Willett, our country’s pre-eminent nutritionist and the director of the nutrition program at the Harvard University School of Public Health, admits he once advised eating margarine over butter — although he now embraces a diet low in red meat but high healthy fats. The best advice he has, though, remains this: “Have fish twice a week.”

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