Don’t let its fancy name fool you. A ketogenic diet is, essentially, a low-carb, high-fat diet—albeit one taken to extremes.

“In a clinical setting, a strict ketogenic diet would involve ultra-low carb consumption, like 20 or 30 grams a day,” says Dr. Eric Westman, director of the Lifestyle Medicine Clinic at Duke University. That’s about the number of carbohydrates in one small apple.

Westman’s research on carb-restricted diets suggests they can help reduce appetite, spur weight loss and improve markers of heart disease. His findings aren’t outliers. From Atkins and South Beach to Mediterranean and Zone, low-carb, high-fat diets—or “LCHF” plans—are all the rage, and growing evidence suggests they’re a big improvement on the typical carb-heavy American diet. But the “keto” diet is the most carb-restrictive member of the LCHF gang.

Along with slashing carbs, a ketogenic plan also calls for limiting your protein consumption. If you know your macronutrients, you recognize that cutting carbs and restricting protein means seriously upping your fat intake. And that’s exactly what a true ketogenic diet entails. “You’d want healthy fats to account for about 80% of your calories, and protein around 20%,” Westman says. (For comparison’s sake, the average American gets roughly 50% of her calories from carbs, 15% from protein, and 30% from fat, per the CDC.)