Protein Basics

What is protein?

Protein is one of the three essential macronutrients, besides carbs and fat. Basically, macronutrients make up our food and we use them as energy source and as building blocks for our body. Protein is considered to have 4 kcal per gram.

Proteins consist of smaller molecules called amino acids. These are the building blocks the body needs! There are 20 of them that the body can use to synthesize its own proteins. 9 of them (Histidine, Isoleucine, Leucine, Valine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan) are essential, which means we cannot make them on our own, but we must get them from our diet.

Protein in the body

Protein plays a crucial role in your body! It's not just "muscle". Every cell in your body is about 50% protein! Protein is also what holds you together. 30% of the total body protein is collagen, an important structural protein. It basically glues you together! Proteins are not only needed for tissue building, but also for your immune system, your enzymes and your hormones. So, if you are deficient in protein, or I should rather say in certain amino acids, you become sick more easily, your body cannot function properly and you become moody or depressed or tired.

There's also a store for aminos in our body, namely in the blood, the muscles, and the digestive tract. It's called the amino acid pool. This pool is especially important for the essential aminos, because we cannot make them on our own. By being stored in this pool, they are always available. When the body needs to synthesize some protein dependent structure, an immune cell for example, it takes the aminos it needs from this pool. But as this pool is fairly small, we need to refill it from time to time. And how do we do that? Through food of course.

Protein is protein is protein?

Not every protein is equal.

Every protein consists of different ratios and numbers of amino acids, which makes them structurally and functionally unique and different. The proteins from chicken meat are different than the ones from milk and the ones from quinoa and eggs and spinach and so on. That's why it is important to not single source your protein. Don't just eat your whole requirement only from Greek yogurt or lean chicken breast or soy, if you are vegetarian or vegan. You might be missing on some crucial aminos there^^ This leads me to the following question:

How much protein do we need?

Generally, about 0.8g per kg of body weight (BW) are recommended. This means if you are a 60kg woman, you need about 48g of protein per day. Now, there are some points were I don't really agree with that. Babies and younger children for example need more, because they are rapidly growing and building new tissues. Also, older people do need to eat more protein, as they become less efficient in metabolizing it and extracting and using the aminos. Moreover, degenerative processes such as age-related muscle loss could be prevented with a higher protein diet. If you are strength training, moving a lot or if you are very stressed, your protein intake should also generally be higher than 0.8g per kg BW.

It also depends on where you source your protein from. As mentioned above, protein is not just protein. Animal proteins in general can very well be taken up by the body, as they contain rather ideal ratios of essential amino acids. On the contrary, plant proteins are not that well absorbed, as they lack specific amino acids. This is why, especially vegans and vegetarians, need to intelligently combine their foods to reach an ideal amino acid composition. For example combining corn and kidney beans or eggs and potatoes is a good way to go.

Concluding from that, 48g of beef protein do not equal 48g of bean protein, at least not for our body. Even if you ate 70g of bean protein, the beef protein would be superior. That's were the 0.8g per kg BW do not tell you the entire truth.

What happens if I eat too much protein?

Many people say that if you eat too much protein, it can damage your liver. But that's only a problem if you are already prone to a kidney disease. If you drink enough water, the body has no problem with clearing out the waste that builds up when protein is metabolized.

When you eat more protein than your body currently needs, it is converted into glucose! (That's also why proteins can indeed trigger an insulin response.) This process is called gluconeogenesis and happens in the liver. The glucose is then used as energy source or converted into fat and stored in adipose tissue. So remember, you can gain wait from protein, as you can from the other macronutrients as well, if you overconsume calories. But talking calories, with protein it's a bit special.

Why protein does not really have 4 kcal per gram

Digesting a protein is very demanding for your body. There's a caloric cost when the body has to digest and process protein. This is the so called thermic effect. Up to 35% of the actual calories are burned of because of that! LET THAT SINK IN! About 1/3 of the calories from protein are actaully burned of right away! 

Overconsuming protein is also very difficult, as protein is very satiating. That's one of the reasons why it is easier to lose weight on a protein rich diet compared to a lower protein diet.