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Why We Disrespect Low-Carb Diets

Bad news, low-carb devotees: Your diet of choice is still being picked last for dodgeball. A new ranking of the top 40 diets from nutrition experts at U.S. News has put low-carb diets in the lower third of the list. And the trendiest low-carb diet of all right now, the Ketogenic Diet, or Keto — the high-fat, low-carb model that promises big weight loss by mimicking starvation and is beloved by warrior athletes and famous celebrities — ranked last. In a two-way tie for first place comes the Mediterranean and DASH diets, whose low-fat, plant-based approaches have been touted for years.

Low-carb diets have always been easy to mock as fad diets, mostly because of the people who love them. Low-carb cultists possess a joyless fascism about food in their uncanny ability to not need bread, one of the most widely consumed foods on Earth. Also, don’t forget their obsession with CrossFit and compression socks, and insistence on telling everyone all the time about their diet. We’ve been calling for their retirement for years.

South Beach, Atkins, Paleo and the like have always been confusing, too: They lead to big weight loss, lure with the promise of bacon over buns, but they’re so restrictive and unpleasant that they’re impossible for mortals in cubicles to maintain. Critics have long argued that they’re also medically unsafe: that too much protein is bad for your kidneys, and maybe the weight loss is just water.

After all, in what world can piling on the sausage be a good thing?

But since the carb-slashing craze of 20 years ago, more research has been done, and low-carb has slowly worked its way up the diet ladder into semi-respectability. Carb restriction works exceptionally well for some people, and evidence says its beneficial to fitness and health because carbs are “uniquely fattening.”

So why do low-carb diets still get such short shrift in lists like this?

Over at the L.A. Times, nutrition experts/writers Gary Taubes and Nina Teicholz offer some theories as to why. In an op-ed titledU.S. News is Wrong About What Constitutes the Best Diet,” they accuse these 25 dietitians, nutritionists and doctors on the panel as “merely recapitulat[ing] questionable dietary advice that has gone by a succession of names since the 1970s.” Advice, they argue, that Americans have followed for nearly a half century, cutting back drastically on milk, butter, meat and eggs, only to be repaid with skyrocketing rates of obesity and diabetes, our two biggest public health concerns. (I have no idea if the same people who cut out milk and eggs are the same people struggling with obesity and diabetes, though.)

Their theory is that these panelists are “entrenched in their opinions, supported by the industries that benefit from these diets, motivated by non-nutrition agendas such as animal-rights activism, or they might simply have fallen into the easy convenience of groupthink.”

As a result, the experts routinely ignore the fact that low-carb diets are particularly effective at addressing obesity and diabetes. They write:

Low-carbohydrate diets have now been tested in at least 70 clinical trials on nearly 7,000 people, including a wide variety of sick and well populations, mainly in the U.S. Thirty-two of these studies have lasted at least six months and six trials went on for two years, enough time to demonstrate the lack of any negative side effects. In virtually every case, the lower-carb, higher-fat diets did as well or better than competing regimens. The cumulative evidence shows that low-carb diets are safe and effective for combating obesity, highly promising for the treatment of Type 2 diabetes and they improve most cardiovascular risk factors.

But what low-carb diets still aren’t is easy to follow, and it appears this was a key factor in making the U.S. News list. Stephan Guyenet, one of those 25 experts on the U.S. News panel, is a neuroscientist specializing in obesity. At his website, he explains that the diets were ranked by four factors: their effectiveness for short-term weight loss; long-term weight loss; ease to follow; and support for general health. And here’s where low-carb diets don’t make a list for best-in-class.

They may help you drop a few pounds quickly, but with Keto, for instance, because it forces the body to hover in a state of ketosis (so the body is effectively fueled off fat), it’s not just restrictive, it’s not just that you feel terrible and can’t maintain it long-term, it’s also difficult to determine what the long-term effects are of a such an extreme diet even if you could do it forever.

Guyenet goes on to point out that a low-carb diet is probably not going to be a total disaster long-term, and it seems especially reasonable for diabetics or anyone with blood glucose issues. It’s just there’s a lot we still don’t know, and many of the tests we draw from are animal models. Plus, it lacks that stickiness factor: In one study, most folks couldn’t maintain Keto for more than six months.

If diets, then, were kind of like our taste in art, the argument would be this: Obscure Tarkovsky films may nourish the mind and soul deeply, and if we could all live on the highest art forms all the time, we’d probably be a much better society. But at some point, everyone breaks down and watches an episode of The Bachelor. (Sure, we could get Tarkovsky to direct that Bachelor episode — if you want to really confuse yourself, check out the Keto Mediterranean diet — but he’s dead, just like we’ll all be one day, no matter which diet we pick.)

So what should the average person who just wants to be healthy take away from all this? It’s not that low-carb can’t help you, and it’s not that Mediterranean will save you. The list isn’t a definitive argument settler on the best thing to put into a human mouth, much less your own. If anything, it merely perpetuates the nutritional whiplash wrought by the debate over what the hell you’re supposed to eat (or not eat) for your own personal, optimal health.

If there is anything to be gleaned here, it’s that there’s still no one best diet for everyone, but that all diet advice needs to consider your particularly entry point — the factors that address your health, your health goals, your ability to change the way you eat and your ability to do this in a deliberate, thoughtful way for most of your life. This is likely why nutrition advice has increasingly led to a more personalized approach to diet, customized based on your unique DNA and blood response to food.

Unsurprisingly, though, this isn’t a slam-dunk either.

Called nutrigenomics, the concept is that your genes tell you what foods are best for you, and which ones you should avoid. Theoretically, you send off a DNA test which reveals that, for instance, you don’t metabolize caffeine or lactose that well, or that half your daily food intake should be devoted to protein. Such companies — one is called Habit and costs a few hundred bucks to receive a personalized nutrition plan — claim that the more personalized the diet advice, the more likely you are to follow it.

Yes, there are critics. Some of them, like geneticist Rasmus Nielsen at UC Berkeley told Vox, argue we simply don’t understand enough about genetics and nutrition to create personalized plans for diet. What’s more, there’s no data to indicate these companies can guide us in this way at this time. It’s not that the idea of a personalized diet is junk — research shows we don’t all respond to glucose in the same way, any more than we do to sushi or whole grain bread. There are also questions of environment, lifestyle, metabolism, gut bacteria, and other factors to consider (and these factors could change week to week, even.)

It’s that we don’t know enough to know how to navigate our genetic differences and specific resulting dietary needs. Which means that, in a sense, we should be as skeptical of a best-diet list as we are of a company asking $200 bucks to tell us how much red meat to eat today.

“At the end of the day, if we really could get the majority of the population to eat wholesome real foods most of the time — regardless of macronutrient composition — most of the nutrition-related problems would be resolved,” nutrition professor Christopher Gardner told Vox.

In other words, no matter what U.S. News or low-carb zealots say, the best diet is still the one we’ve always known: the healthiest one you can stick to.