This brought to mind the self selected macronutrient study performed on
mice by Ortman, Prinzler and Klause. They allowed
mice to select their own diet and, lo and behold, the mice chose (by calories, not weight!) 82% fat and 5.6% carbohydrate. Sensible mice.
NB These German mice should each be given Professorships of Nutrition at medical schools in the most obese nations of the world.