What Is Speed Keto—and Is It a Sustainable Diet?

'Combining keto with intermittent fasting is not a magical solution.'

Despite its continuing popularity, many RDs don't recommend the keto diet because it is highly restrictive—the permitted carb intake is very low, typically 20 to 50 grams per day, which requires careful planning. And now keto controversy has taken a new direction, thanks to Speed Keto.

A digital program created by Dr. Harlan Kilstein (who is not, incidentally, a medical doctor but an "expert coach and motivator" with an EdD, doctor of education, degree), Speed Keto claims to solve some of the "pain points" of those following the keto diet. According to Kilstein's website, a lot of people get frustrated counting calories and macros, or they don't know how to deal with the weight-loss stall that sometimes comes when the body has been in a ketosis state for a few weeks.

"Basically, Speed Keto is a hybrid program that combines the traditional ketogenic program with intermittent fasting," Tony Castillo, RDN, nutrition consultant for RSP Nutrition, tells Health.

Speed Keto still focuses on putting the body in ketosis (when the body uses fat for fuel instead of sugar) and has a similar diet protocol to traditional keto: high fat, moderate protein, and low carbs, Castillo says. But the intermittent fasting (IF) element of Speed Keto is the big difference.

"Intermittent fasting is the practice of fasting for several hours and therefore only consuming food within a specific number of hours," Castillo says. "Typically, fasting takes place for 16 hours, with food consumption restricted to an eight-hour time frame. The goal of the Speed Keto program is to incorporate the practice of IF," he explains. Eventually, people on the program eat just one meal per day, one that is low-carb, moderate-protein, and high-fat.

Does Castillo recommend it? In a word, no.

"I don't see any pros for this diet," he says. "First of all, a diet program focusing on high fat, moderate protein, and low carbs is typically unsustainable and can be challenging to follow long term."

It's also important to consider the potential mental side effects of Speed Keto. "A diet program that incorporates IF may not be ideal for someone with a history of binge eating disorder," Castillo says. He also points out that the long-term effects of high-fat diets in general are unknown. "Originally, they were created for people with epilepsy, not laypeople," he says. And if one of your fitness goals is to build muscle, following a keto-type diet program could be an obstacle you don't need. "The body's main source of energy comes from carbohydrates," Castillo says. "Without them, lethargy is common, which makes strength work more challenging."

Kilstein's credentials and authenticity have also been called into question. A quick scan of the reviews for his only book currently available on Amazon, Completely Keto Cookbook: Recipes You'll Swear Aren't Keto!, reveals at least a few disappointed customers. "At a minimum I have to describe the bulk of the recipes as unimaginative," wrote one, while another said, "Regurgitated recipes, no nutritional info, no macros, incomplete or poorly written instructions from a newbie trying to make a buck off of keto dieters."

Many experts agree that the keto diet is very difficult to sustain, especially in social situations. "There is no long term research on the effects of the keto diet, and there is also no evidence to show that a keto diet is more effective than a low-fat or low-calorie diet in the long term," New York-based nutritionist Lauren Harris-Pincus, RD, tells Health. "I think the larger problem with keto is a lack of nutrient dense foods like fruits, whole grains, beans, and other fiber containing foods. In my opinion, no one should attempt a diet that eliminates whole food groups without medical supervision."

And when it comes to Speed Keto, Harris-Pincus has even more reservations. "This diet was developed by someone who is not an MD or dietitian to sell you something," she says. "Combining keto with intermittent fasting is not a magical solution. IF simply reduces your eating window so people tend to consume fewer calories in a day since you cannot snack continuously."

Ultimately, the only way to lose weight is to create a calorie deficit. "Keto helps you do that by eliminating so many of the common foods we eat every day," Harris-Pincus says. But before you start on the keto diet—or any variation of it—it's wise to consider more nutrient-dense alternatives.

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