We all know about the current dietary movement (read: "fad") to eliminate carbohydrates. Several diet wizards have proclaimed that protein is the key, and that we should eat lots of it. They say that sugar and carbohydrates are unhealthy. Further, a lot of so-called "experts" tell us we're allergic to grains, especially wheat flour. Moreover, we're told that fruit is also an enemy. We should stick to protein, and lots of it.
Do what you want, believe who you will--but if you ask me, I'll tell you that eating only meat with little else will eventually make you sick. All of that fat, all the excess protein from a lot of meat, and the lack of vitamins and fiber from fruits and vegetables, plus less energy from the elimination of carbohydrates, eventually catches up with you. An excess of protein over time can contribute to digestion problems, liver and kidney diseases, and some studies say it's even carcinogenic.
I believe that we need carbohydrates in our daily diets, but in structured amounts. We also need fruits and vegetables (3-5 servings a day). A little dairy for calcium is required (two servings a day), especially for women. A little protein from nuts, fish, poultry, and a tiny bit of meat is all the protein we need (two servings a day). Yes, we even need a little bit of fat. What I'm saying is have a small amount of everything, in moderation, in balance. Not too much of any one thing.
Our bodies need a lot of different things. We have a lot of internal organs and a multitude of nutritional needs to keep them running well. Just giving our bodies one type of fuel isn't enough.