The ketogenic or “keto” diet is a low-carbohydrate, fat-rich eating plan which can include sources of unsaturated fats, such as nuts, seeds, avocados, plant oils, and oily fish, but also foods high in saturated fat, such as fatty cuts of meat, processed meats, lard, and butter.
In an interview with Business Insider, Dr. Walter Willett, professor in the Departments of Nutrition and Epidemiology at the Harvard T.H. Chan School of Public Health, suggests that keto dieters prioritize unsaturated fats over saturated fats, given limited evidence on the diet:
“The reality is that we don’t have long term studies of people on keto diets…given that big gap, what we see in general for good health, is that the type of fat is really important. It’s not all bad, it’s not all good, and emphasizing mostly unsaturated fats in a diet has positive health benefits.”