Very low-carb ketogenic diets surged in popularity in the 1990s and now are more popular than ever. Several celebrities attribute their weight loss and physique to the ketogenic diet, and the hashtag #keto yields more than 8 million results on Instagram. The ketogenic diet is a high-fat, low-carb diet that sends your body into a state of ketosis, during which it uses stored fat as energy. A keto diet prohibits high-carb foods, whether “healthy” or not. That is because having too many carbs will put your body out of ketosis.