What proteins? Obama became veg, u see him without energy?
any vegetable, and rice, lentils, salads, any kind of fruit, is way more healthier than eat meat.
Carbs and Fat (more energy than Carbs) gives you energy, not proteins. Proteins can give you energy, but it's a waste since the most energy gives you carbs and fat, and proteins gives you very little energy comparing to the other two.
Proteins build your body, and the most proteins comes from the animal food (chicken, pork, beef etc.)
If you wouldn't eat proteins at all your body would start to literally eat your own proteins that you have in bones, tissues etc. until you would die. This is because proteins is the only food ingredient which your body can't produce from other ingredients. Your body can produce (through some cost) carbs from proteins, or fat from proteins (first to carbs and then to fat), but it doesn't go in reverse.
Vegetables have very little proteins, almost none. There are only couple vegetables who have significant number of them, and one of them is beans.
Man was never a vegetarian. The nature created a man, not some "vegi" supportes who are making sad faces when animals are killed.
Man is a super predator, just like REX was, although he is not that tall, but is a lot smarter. Man is a predator, he always was, and the basic food source for him was meat since his creation.
Some time ago I've read a very nice phrase:
If we take all the ages that man kind exist and evolve, and put it into one day timespan, we eat so much of non-animal food (mostly carbs through sugar, sweet stuff, but also grain - bread products) for just couple of minutes.
Vegetables are important. But so is meat.