My post had become long enough without going into a detailed discussion of fat vs. carb for energy. Suffice to say, both will work but there is a difference between "workable" and "optimal". In a survival situation you have precious little control over many important factors, so it is a good move to optimize factors you can control, i.e. your emergency food stash. Look for some of Marc Twight's material on food strategies for high altitude alpinism, it is helpful.

From Golden & Tipton, p. 171:

"Historically, fat has been a favorite constituent of such rations because of its high energy density and flavor. To maintain blood glucose levels, however, a high carbohydrate diet rather than a high fat diet is the preferred way of providing energy..."

Read their book, it is extremely detailed and well researched. Golden is a MD and PhD with over 30 years in the British navy studying sea survival and survival physiology. Tipton is a PhD having over 20 years experience with Britain's Naval Medicine Institute.