A ketogenic diet – or keto diet – is a low-carb, high-fat diet. It can be effective for weight loss and certain health conditions, something that’s been demonstrated in many studies. A keto diet is especially useful for losing excess body fat without hunger, and for improving type 2 diabetes or metabolic syndrome. On a keto diet, you cut way back on carbohydrates, also known as carbs, in order to burn fat for fuel.