The 4 sources of food energy are fats, carbohydrates, alcohol and proteins. Per unit of mass fat has 2.4 times more energy density than either carbohydrates or proteins. Sugar alcohols have an even lower energy density. High quality animal sourced proteins contain all the essential amino acids we need to grow and maintain various body tissues. Fat provides plenty if energy to fuel the muscles that high quality proteins built. Therefore, meat is a nutrient dense food. Fresh meat is also a good source of B-vitamins.
Modern sedentary lifestyles often causes energy from all 4 food sources to be stored in our bodies as fat. In years gone by, fat stores were extremely useful in getting humans from one “famine” to the next “feast” (think winter versus summer). Today it makes a lot of sense for us to limit our fat, carbohydrate and alcohol intake. Still, the judicious use of fats can help us enjoy eating beneficial animal protein. Fat helps keep cooking meat moist as it largely renders out, leaving the characteristic species flavor behind (pork, beef etc.).
However, in emulsion type meat products (wieners and bologna) up to 30% formulated fat is encapsulated by protein in a solubilized protein-salt-water matrix. In that instance no fat renders out when cooked and the full formulated fat amount is consumed.
Fresh, meats cooked using low to medium heat are the healthiest, but grilling, broiling or frying are fine when practiced in moderation. Long-aged and fermented meats are much more prone to amine formation and fat oxidation.