The latest — or maybe just loudest — diet obsession transfixing the internet says it will help you lose weight, live longer, and improve your memory. Sounds great, you say? Except that these benefits will only bloom once you cut carbohydrates. Familiar story, right? The Atkins diet is back? We’re all gonna start eating eggs and bacon for every meal again until our cholesterol inevitably reaches code-red levels?

No, this new obsession is not Atkins. It’s the ketogenic diet, lovingly called “keto,” popularized by actors, Instagram stars, and the same people who brought you raw water.

If you believe a diet is supposed to be a varied landscape of all the things the world has to offer in moderation, keto may not be the diet for you. Let’s find out if science says it’s worth it.

What is the ketogenic diet?

The history of keto goes much farther than an attempt to stem weight gain during our fat-fearing era. In 1921, it was observed that fasting decreased incidence of seizure in epileptic patients. The same year, reports noted cognitive improvement and reduced seizure activity in epileptics who fasted for two to three days (fasting has been used as far back as 500 B.C. to treat epilepsy).

Around the same time, it was discovered that the metabolic change caused by fasting that controlled seizures also occurred when a patient stopped eating carbohydrates. It was then that an endocrinologist named Dr. Rollin Woodyatt had a scientific breakthrough: he found that the compounds acetone and beta-hydroxybutyric acid were detectable in high levels in fasting patients (to be fair, they can also be present in urine in low levels normally, and things like dehydration can trigger a false positive test). These compounds are classified as ketones, produced via the metabolic state of ketosis, which occurs when an elevated level of ketones are produced as a result of the body using fat for fuel as stored carbohydrate is depleted.

The ketogenic diet keeps coming back into the larger consciousness, to the consternation of medical professionals.

Doctors at the Mayo Clinic created a formula that manipulated the ketogenic effect that came with complete fasting by instead limiting a patient’s intake of carbohydrates. This was the genesis of the ketogenic diet. To manage childhood epilepsy, the prescribed diet consisted of one gram of protein per kilogram of body mass — a max of 15 grams of carbs — and the rest of the calories from fat. Et voila: the ketogenic diet was born.

A strict version of the diet is still used to manage drug-resistant epilepsy. But it’s fallen out of favor because the success rate of a large suite of readily available anti-epileptic medications. It’s been observed that children on this diet for epilepsy don’t generally become overweight and tend to lose some weight in the first few months on the diet, but it’s not without its drawbacks. Children on keto tend to have higher cholesterol than other children in their age range and there can be some nasty side effects, including kidney stones. Due to the public’s appetite for miracle weight-loss cures, however, the diet keeps coming back into the larger consciousness, to the consternation of medical professionals.

how keto was reborn as Atkins was reborn as keto

In 1997, a book titled Dr. Atkins New Diet Revolution climbed up the bestseller list for five years after it was first published (this edition of Diet Revolution was little more than a cosmetic overhaul of Dr. Robert Atkins’s 1972 book, Dr. Atkins Diet Revolution, which didn’t quite revolutionize diets in the way publishers hoped).

But this time around, America was primed for Atkins’s theory that it wasn’t fat but carbohydrates that caused weight gain. Food manufacturers and consumers had cut fat from their diets but obesity rates continued to rise; something was due to be the new culprit for our weight woes. Dr. Atkins was further vindicated by 2002 article by the science journalist Gary Taubes in The New York Times Magazine. “If the members of the American medical establishment were to have a collective find-yourself-standing-naked-in-Times-Square-type nightmare, this might be it,” Taubes wrote. “They spend 30 years ridiculing Robert Atkins, author of the phenomenally-best-selling Dr. Atkins’ Diet Revolution and Dr. Atkins’ New Diet Revolution, accusing the Manhattan doctor of quackery and fraud, only to discover that the unrepentant Atkins was right all along.”

At one point in the early 2000s, approximately 10 percent of the country was on a low-carb diet. That’s insane. What’s more, people actively started avoiding carbs even if they weren’t on a diet. “A year ago, if you asked consumers what they watch, 11 percent would have said carbs,'' Michael Polk, the chief operating officer at Unilever-Best Foods, told The Times. “Today if you ask, 40 percent of consumers say they are watching carbs. In our opinion, this has evolved into a major shift in consumer behavior.” Atkins was able to build an industry out of his diet advice: Atkins Nutritionals, which cranked out low-carb meals and snacks, was at one point valued at approximately half a billion dollars.

At one point in the early 2000s, approximately 10 percent of the country was on a low-carb diet.

So why did Atkins fall out of favor? Well, the diet’s delightful side effects could include fatigue, constipation, excessive thirst, bad breath, the dreaded meat sweats, and worst, the look your friends would give you when you said you were on Atkins. There was also the fact that the diet wasn’t really sustainable (kinda like most diets, funnily enough). In 2003, a pair of studies in the New England Journal of Medicine found that most of the weight one initially lost while following Atkins was water weight; and subjects who followed the diet typically gained back any lost weight in six months.

Atkins Nutritionals filed chapter 11 bankruptcy in 2005, a year after the doctor died after falling on an icy New York City sidewalk. Still, Atkins had a long-lasting impact on the dietary landscape in America. “Sugar free” and “low carb” labels never left the snack aisle. People still fell back on the idea that to lose weight, one simply had to cut carbs. But all the while, obesity rates climbed from 30 percent up to 39 percent of the country, priming the stage for another diet “revolution.”

the Rise of The Keto Gurus

Losing weight has become a challenge to be solved through innovation, and the new diet gurus don’t take kindly to the scientific method. It’s in line with Dr. Atkins’s legacy; he was a huge proponent of alternative and unproven medical treatments beyond just his ideas about nutrition. You almost can’t blame him or the other diet gurus for leaning in on the techno-bullshit market; it’s hard to fill up a 300 page diet book on “eat a bit less and find a type of exercise that doesn’t make you hate life.”

Dave Asprey is one such tech guy-turned-low-carb guru. Asprey is now the CEO of Bulletproof 360, which sells butter-larded coffee and myriad supplements to the masses — and which raised $19 million in Series B funding last year. Over the past two decades, Asprey says he’s spent $1 million to “biohack” his body, turning it into a fat-burning machine and even increasing his IQ by 20 points. (Asprey has also said that he blocks waves out of his cells with glasses and takes supplements to help with the “low oxygen high EMF [electromagnetic field] environment” on airplanes, so.)

I’ll give Asprey this: people have told me that the buttered coffee tastes okay and makes them feel energetic. The coffee is also, of course, keto-approved:

“The Bulletproof Diet uses ketosis as a tool, but tweaks it for even better performance,” goes a blog post on the Bulletproof website. “It is a cyclical ketogenic diet, which means you eat keto for 5 to 6 days a week and then do a weekly protein fast, which lowers inflammation and kickstarts fat-burning. This is much better for your body and spurs weight loss even more.”

But about that weight loss.

Between the butter and the so-called “Brain Octane Oil” that are part of the Bulletproof coffee recipe, any increased energy one feels after consuming it could have something to do with the nearly 500 calories of fat that are in it. As has been pointed out, those calories displace other more nutrient-dense sources of fuel. Asprey also claims that his coffee is better for you because it doesn’t contain mycotoxins, i.e. toxins produced by fungi. Though it’s true that mycotoxins can be dangerous for your health, the possibility of any roasted coffee available on store shelves containing mycotoxins is slim to none. It’s like slapping “this coffee was not made with white rhino horn” on the label.

Calories still matter

Keto devotees sometimes brag about how they eat more on the diet than ever before and still lose weight. On keto, their bodies have turned into fat-burning machines that give the finger to the laws of thermodynamics, or something.

Let’s hold up a sec. Allow me to introduce you to the DIETFITS Randomized Clinical Trial, published in February 2018 in the Journal of the American Medical Association. DIETFITS, which stands for Dietary Intervention Examining the Factors Interacting with Treatment Success, succeeded in busting a slew of dietary theories. Microbiome is responsible for everything? Nope. Predisposition to success on one diet based on genetics? Nah. Low carb over low fat? Uh-uh.

Over the course of a year, 609 participants were randomly sorted into low-fat or low-carb diet groups. They were given instruction on healthy habits and choices, along with practical advice on how to stick to the diets to which they had been assigned. Additionally, and possibly most importantly, they were instructed to keep their caloric intake limited similarly in both groups.

It’s fairly common that, initially, low-carb dieters see more weight loss. This is because glycogen molecules bind with water, and once you’ve burned through your most readily available source of energy, you’re also down a few pounds of water weight. Over time, that weight loss of the low-carb group evened out with the low-fat one; there was ultimately just a 1.5 lbs difference in weight loss between the two groups — the low-fat group lost an average of 11.7 lbs the low-carb group 13.2 lbs. This is a difference reflective of which group took a shit before or after going for their final weigh-ins.

It’s fairly common that, initially, low-carb dieters see more weight loss. But it doesn’t last.

A few variables were tested in conjunction with weight loss. One was initial insulin secretion, specifically to see if it had any affect on loss in each diet group. It did not. They had also checked a few genetic markers that were suspected to give dieters pre-dispositions to success either on low fat diets or low carb diets based on previous studies. However, genetics were shown to have no effect.

But the most important takeaway from the study is that similar numbers of participants lost and gained similar amounts of weight in both groups. As Examine.com shows in its analysis of the study, charts comparing weight loss (or gain) from each group are almost identical.

In the beginning of the study, all participants were instructed to consume either ≤20 g of fat (if in the low-fat group) or ≤20 g of carbs (if in the low-carb group) for the first two months, after which they could increase either their fat or carb intake to levels they felt they could sustain indefinitely. By the end of the trial, the vast majority had not been able to maintain such low levels. The final dietary recalls reported an average daily fat intake of ≈57 g (low-fat group) and an average daily carb intake of ≈132 g (low-carb group).

Part of what makes a diet work in the long run, of course, is a person’s ability to stick with it, and most diets that cut out an entire food group or macronutrient are not sustainable.

Curiously, this study was funded by the Nutrition Science Initiative (NuSI), a group with the aim of producing “conclusive results in the next decade” in a sometimes confusing nutritional landscape. They claim our nutritional guidelines are “based on inconclusive science,” and though their website doesn’t directly indicate any bias, their research so far focuses on the effects of carbohydrates on obesity. This was the second published study that received funding from the institute. In the first study, published in the American Journal of Clinical Nutrition in 2016, researchers hypothesized that a low-carbohydrate diet increased energy expenditure. Results said otherwise:

The carbohydrate–insulin model predicts that the KD would lead to increased EE, thereby resulting in a metabolic advantage amounting to ~300–600 kcal/d. Our data do not support EE increases of that magnitude. (...) In summary, we found that a carefully controlled isocaloric KD coincided with small increases in EE that waned over time. Despite rapid, substantial, and persistent reductions in daily insulin secretion and RQ after introducing the KD, we observed a slowing of body fat loss.

In layman’s terms: people burned marginally more calories at first, but there wasn’t evidence that the diet increased caloric burn in the long term.

I suppose it’s not a surprise that, per an investigation from Wired, NuSI seems to be having trouble scrounging up financial backing lately.

Keto and Low-Carb now have the same problem as Low-Fat

Remember those insanely awful Snackwell’s cookies and the chips that gave you anal leakage? We were willing to suffer so much for the price of “weight loss.” Snackwell’s. Christ.

We soon learned that low-fat diets only work if a dieter is also controlling their calories. Five thousand calories of broiled dried out chicken breasts, kale, or anal-leakage chips is still 5,000 calories. Low-fat content or not, those calories add up.

Low-carb has become the new low-fat. During the early Atkins era, snacks included cucumbers, beef jerky, and pork rinds. Now there’s a wealth of low-carb snacking options; there are junk-foody low-carb recipes all over Pinterest; a low-carb aisle at the grocery store. There are low-carb replacement foods and ingredients for low-carb replacement foods. It’s Snackwell’s 2.0.

Remember Snackwell’s? Lol.

Want candy but you don’t want to stray from keto? A low-carb peanut butter cup has about the same calories, gram per gram, as a Reese’s. Want to slap all that bacon between something other than lettuce wraps? Some low-carb bread will run you $7.99 per loaf whereas bread that doesn’t taste like sadness with the same number of calories per slice is generally about half the cost. How about chocolate? A chocolate brand that boldly calls itself ‘The Good Chocolate’ is sweetened with a sugar alcohol commonly associated with some nasty gastrointestinal effects when consumed excessively. It’s also $8 for a 2.5-oz bar, and about as calorically dense as a Hershey’s bar. Low-carb flour? Not surprisingly, it costs more than normal old flour, and the more expensive one has more calories.

Bacon: A balanced breakfast?!

Here’s the thing: Low-carb diets absolutely have a track record of working. A 2017 study in Diabetes & Metabolic Syndrome: Clinical Research & Reviews showed significant weight loss, improvement of health markers related to diabetes, blood pressure, and cholesterol in participants who followed the diet for 10 weeks. If you have been advised to lose weight by your trusted medical professional and your doctor or dietitian says this is appropriate for you, a low-carb diet can help you lose weight.

But low-carb diets don’t work because of how people seem to think they work — more specifically, through something called the “insulin hypothesis,” which says that removing carbohydrates from your diet stabilizes insulin and blood sugar levels, subsequently increasing your metabolism and reducing your hunger. This hypothesis has failed several studies. A review study published in the European Journal of Clinical Nutrition in 2017 reported it as “carefully controlled inpatient feeding studies whose results failed to support key [carbohydrate-insulin] model predictions.” Sad.

A common belief among keto devotees is that your body not only switches to burning fat on keto but that a low-carb, high-fat diet turns you into a “fat-burning machine.” Now that you’re not eating pizza crust, your body is going to burn through all of its own fat, calories and laws of thermodynamics be damned. But you don’t magically burn off your love handles just because you changed your fuel source. As much as the three macronutrients have different uses in the bodies, when it comes to gaining and losing weight, calories are calories are calories.

Someone trying to follow the keto diet to a letter may not even go into the much-desired state of ketosis. Sure, you can buy those little piss strips that react to ketones in your urine to reassure you that you’re “in ketosis,” but you’re probably wasting your money. Ketones are present in low levels in your urine even if you’re not on a ketogenic diet. Measuring ketones via blood is far more accurate (if not overly invasive for a diet), but to measure them for weight loss in the first place is borderline useless, especially in urine.

One of the most extraordinary claims in Dr. Atkins' New Diet Revolution was the metabolic advantage hypothesis, which theorizes that the inefficiencies in the fat-burning process caused an energy advantage (in layman’s terms, it was hypothesized that using fat for fuel causes you to burn more calories). Unfortunately, a 2006 study in the American Journal of Clinical Nutrition said that calorie per calorie, you’ll lose the same amount of weight on both a ketogenic diet and a reduced calorie, controlled carb (but not ketogenic) diet. Amazing what you can get people to believe when you sell some books.

Studies also contradict the claim that the ketogenic diet will help your Crossfit performance, or whatever. A 2018 study published in The Journal of Sports Medicine and Physical Fitness reports that a low-carb diet inhibited cardiovascular performance. Want to check that half marathon off your bucket list? Science says eat your carbs. Multiple studies have shown similar results. The best news I can tell you about keto is that a 2017 Journal of Human Kinetics study said that it can help maintain a lower body weight, which can help athletic performance. But the study also said that “some aspects regarding the effects of long-term LCHF diets in athletes are still unexplored and in need of investigation, including (...)Strength, power, psychological status, and perceptual-motor performance after weight loss.” So, take that with a grain of low-carb salt.

So what do i eat?

You could pick any of the countless diet books on the market, follow their plan to the last calorie, and lose weight. This is because — as study after study has shown — calories and dietary adherence matter more than anything for weight loss. You can gain or lose weight on any combination of foods. People have lost weight on twinkies, McDonalds, juice, plants, and obscene amounts of meat.

It’s important to remember weight loss alone doesn’t necessarily cause all health markers to improve, and a diet causing weight loss does not mean it’s appropriate and healthy for everyone. Some foods are better than others at making weight loss and maintenance easier for different people, so balancing a diet is a fairly personalized thing. If your doctor gives you the green light and keto works for you, do it. If low fat works for you, do it. If plant-based, paleo, Mediterranean, or one of the zillion other diets help you improve your health and your relationship with food? Do it. There’s no one right way to eat for everyone, just as there is no miracle diet plan for weight loss.

And please, talk to your doctor and a registered dietitian when considering a new diet plan. And maybe just have a piece of bread and don’t worry about it.

Listen to an interview with Yvette on The Outline World Dispatch.

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