Nutritionfacts is a pseudoscience site.

The paleo diet is definitely, absolutely bullshit, but ketogenic diets have real use and purpose, if you can adhere to a strict ketogenic diet, and can do so without becoming malnourished (both of which are damn near impossible for most people). If you can get your body into a state of ketosis--not ketoacidosis, which is a potentially fatal condition most often associated with diabetes--then you burn off body fat much, much more quickly when you're on a calorie-deficient diet, because your body is already using fats as a primary source for energy rather than carbohydrates. The downside is that you'll feel like absolute dogshit for a few days until you adjust, since glucose is the preferred fuel for cellular respiration.