The okinawans and whatever of these groups pointed towards all eat meat in proper proportions. That is the key. If you study holistic medicine like TCM, you will come to understand that red meat has the properties of: blood building, heating, fatty and stagnating. This means it is very nourishing, but must be taken in small amounts and balanced with cooling foods like vegetables. This prevents any stagnation diseases like cancer and diabetes, or heat diseases like inflammation and high blood pressure. Chicken is neutral, fish is neutral, with some cooling and few heating. This is why they are seen as "better" choices.