The ketogenic diet, originally developed as a treatment for childhood seizures, has been gaining popularity as a weight-loss tool. It’s the focus of numerous titles this season, and like any diet, it takes some getting used to—perhaps more than most.

The nutritional requirements alone are unconventional. According to Amy Ramos’s popular 2016 guide, The Complete Ketogenic Diet for Beginners (Rockridge; 419,000 print copies sold), people following the plan should aim to get 65%–75% of their calories from fat, 20%–25% from protein, and the remaining 5% or so from carbs.

On top of that, serious keto dieters need to be able to determine when they’ve entered ketosis—the state during which the body, deprived of carbohydrates, converts fat into compounds called ketones, which replace carbs as the body’s energy source. How do new dieters tell whether they’ve entered this state? By urinating on a ketone testing strip (widely available in packs of 100 for under $10) or using a pricier instrument that measures acetone, a by-product of ketosis, on the breath or the presence of ketones in the blood.

Clearly, this is not your average low-carb diet.

Despite the barrier to entry, the ketogenic diet has become huge in the health and fitness space. Celebrities including Halle Berry and Tim Tebow have said they’ve followed it, and it’s generated significant chatter on social media: the cooking-focused Keto Daily Facebook group, for instance, has 1.6 million followers, and keto-centric Instagram hashtags abound.

Publishers, naturally, have taken notice. In addition to Ramos’s guide, top sellers include The Keto Diet by Leanne Vogel (262,000 print units) and Simply Keto by Suzanne Ryan (131,000), both 2017 Victory Belt publications, and 2018’s The Easy 5-Ingredient Ketogenic Diet Cookbook by Jen Fisch (Rockridge; 117,000).

This season’s titles suggest the diet has moved beyond the Keto 101 phase. Publishers have adapted the program to regional cuisines, as in Natasha Newton’s Southern Keto (Victory Belt, Nov.); dietary restrictions, as in The Essential Vegan Keto Cookbook (Rodale, Nov.); and of-the-moment kitchen tools, as in The “I Love My Air Fryer” Keto Diet Recipe Book by Sam Dillard (Adams, Jan. 2019). “The diet’s early adopters are definitely looking for new recipes to try,” says Brendan O’Neill, editor-in-chief at Adams Media.

Even as authors work to satisfy that demand, keto is relatively new as a weight-loss program, and that puts publishers in the position of speculators. Will the diet prove enduring, or will it flame out?

Already keto has generated its share of controversy. It tied for last place in the most recent U.S. News and World Report ranking of 40 diets overall, and was ranked 13th out of 40 on its fast weight-loss diets list. October’s Harvard Health Letter says that studies show mixed weight-loss results for people on keto and cautions that the program has a risk of side effects such as constipation, nutrient deficiency, and liver problems.

Further, some dieters going though carb withdrawal develop what’s known as keto flu, an assortment of fatigue, nausea, headaches, and other flulike symptoms. Others report halitosis, or, as the keto community calls it, “keto breath.”

Given the differences of opinion as to keto’s efficacy, we asked publishers how they’re approaching the diet. Which books do they choose to publish? To whom do they market them? And what kind of future do they see for keto?

The Key to Keto

Justin Schwartz, an executive editor at Houghton Mifflin Harcourt, waited before acquiring the publisher’s first keto book, Keto Fat Bombs and Sweets (Mar. 2019) by Urvashi Pitre, a food blogger best known for her viral recipe for Instant Pot Keto Indian Butter Chicken and ensuing cookbook, Indian Instant Pot Cookbook (Rockridge).

“I’m probably the last editor in the business to come around to it,” Schwartz says. “When anything is a little too new, we tend to take a wait-and-see attitude to make sure it seems legitimate and isn’t just a flash-in-the-pan thing that’s going to be debunked immediately.”

To better understand the keto diet, Schwartz joined Facebook groups in which practitioners convened to ask questions and offer support. He saw that many dieters had achieved impressive results and eventually was won over. “It’s hard to argue with really staggering success.”

With any new diet or eating program, a mixed reception is expected, Schwartz says. He cites The Whole30 by Melissa and Dallas Hartwig, which he edited, as an example. The book has sold more than a million print copies since its 2015 publication, and while the Whole30 plan—a 30-day diet that cuts out soy, dairy, grain, alcohol, and the like—remains popular, many nutritionists have been critical, and U.S. News has repeatedly ranked it near the bottom of its best diets list. “It doesn’t matter how many people are having success with it,” Schwartz says. “There are always going to be people who find the downside or simply don’t believe it.”

At Rodale and Harmony Books, associate editorial director Alyse Diamond is likewise enthusiastic about the keto diet. This season, the two imprints will together publish several books on keto: The Keto Reset Diet Cookbook by Mark Sisson (Harmony, Nov.) as well as The Essential Vegan Keto Cookbook (Nov.), The Essential Vegetarian Keto Cookbook (Nov.), and The Essential Keto Slow Cooker Cookbook (Jan. 2019), all from Rodale and by its editors.

Diamond has been interested in keto for more than a year and says the trend “exploded” in summer 2018. “That’s when we started seeing, on BookScan, that 10 of the top 15 cookbooks were keto cookbooks,” she says. “We haven’t seen a trend like this in health in a really long time. It’s kind of like the new paleo. And frankly, it feels bigger than paleo.”

For Diamond, one key to navigating a controversial diet such as keto is to work with specialists in the subject. She names Sisson—a fitness blogger and the owner of Primal Blueprint, which sells health courses and supplements—as one example: “He’s well-acknowledged as an authority in the keto space.” His The Keto Reset Diet has sold 117,000 print copies since it published in 2017; PW’s review called his forthcoming cook-book “a solid, informative follow-up.”

Tracy Behar, publisher and editor-in-chief at Little, Brown Spark, which will publish Keto Diet by Eat Dirt author Josh Axe in February, emphasizes the importance of experts in a new diet category, where rules and best practices have yet to be established. “There’s a lot of bad information out there,” she says, particularly concerning which fats are healthy. “There’s lots of butter and bacon.” (There is, in fact, a book titled Bacon & Butter: The Ultimate Ketogenic Diet Cookbook by Celby Richoux, a 2015 Rockridge publication that has sold 80,000 print copies.)

Publishers are also mindful of including disclaimers and not making lofty promises. Among other claims, keto has been touted as a cancer-fighting diet. “Obviously, as a publisher, I don’t like to make such strong claims as that,” Diamond says. “But we do like to share with readers all the potential health benefits.”

Flavor over Formulas

One way to skirt controversy is to focus less on the science behind a diet and more on the taste of the food. “We’re not really in the business of providing health guidance with the cookbooks,” Diamond says. “The goal, really, isn’t even to get people started on a diet plan.” She conceives of Rodale and Harmony books as targeting many kinds of readers, from hardcore keto dieters to those who are merely curious. “You might be a paleo eater, or you might eat carbs all day every day, but you’ve heard about this trendy diet, and you just want to try out some recipes.”

At Hay House, which will publish Complete Keto by Fit2Fat2Fit author Drew Manning, it’s a mix. “Some of our keto books focus more on science, others more on food and lifestyle,” says editorial director Anne Barthel. “Our aim is to give readers resources they can use to make informed choices about what’s best for them, which they’re advised to do in consultation with their doctors.”

Marissa Giambelluca, acquisitions and editorial manager at Page Street, which will publish Keto Cooking with Your Instant Pot by Karen S. Lee in January, sees the publisher as a Switzerland when it comes to the validity of an eating program. “It’s not for us to have an opinion on a diet,” she says. “It’s how I’m able to have vegan books and paleo books and keto books all on the same list.”

Behar adds that, as the keto diet gains popularity, more studies on it will be done, and more information about its healthiness and efficacy will become available. “As the science grows, the recommendations will become more refined,” she says.

Until the High-Fat Lady Sings

For now, keto shows little indication of slowing down. Grand Central Life & Style will publish The Essential Instant Pot Keto Book by Casey Thaler in January; Victory Belt has several forthcoming titles, including The Keto Diet Cookbook by Leanne Vogel (Apr. 2019), the follow-up to her 2017 hit; and Adams Media will publish, in addition to the above-mentioned air fryer book, Keto Snacks by Lindsay Boyers (Nov.) and Keto Basics (Jan. 2019).

That last book suggests that publishers still see an appetite for primers on the diet, implying that keto continues to attract newbies.

What remains to be seen is whether the diet will last and, if it does, what new forms it may take. “We’re mindful of past diet trends, like gluten-free or paleo,” O’Neill says. The plan, for Adams and for other publishers, is “to see how those evolved and what kind of similar opportunities exist with keto.”

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