There is lot of scientific evidence to prove this. Cooking and processing of any food item alters the chemical composition of food. Raw meat contains all the amino acids that are not altered. Amino Acids build protein. If the amino acids are altered then they can not serve as building blocks for protein or enzyme construction.
Raw meat contains an excellent array of fat including essential fatty acids.
Some fats can become cancer-causing when cooked. The pancreas will never shut down because it does a lot more than provide digestive enzymes. The pancreas also store Beta cells which are important part of the immune system. Infection can be caused by a variety of ways other than diet. Illness can occur due to stress of the body, injury, etc.