What is Protein Metabolism?

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  • Written By: Jennifer Voight
  • Edited By: Melissa Wiley
  • Last Modified Date: 22 January 2020
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Protein metabolism is a description of the physical and chemical processes that cause both the building, or synthesis, of amino acids into proteins and the breakdown, or catabolism, of proteins into amino acids. Amino acids are circulated through the blood and enter the body tissues, where they are synthesized back into protein. Balance between protein synthesis and catabolism is essential to maintain normal cell functioning.

Soft tissues require amino acids to manufacture the types of proteins needed for maintenance of life processes. Amino acid synthesis is necessary to form other essential compounds in the body, like histamine, neurotransmitters, and components of nucleotides. Any amino acids that are left over after synthesis are either stored as fat or converted into energy.

Amino acids can be classified as essential and non-essential. Essential amino acids cannot be made by the body but are essential to protein metabolism. These amino acids must be acquired from food. Non-essential amino acids are required for normal cell functioning and can be synthesized from other amino acids in the body. Once the proper amino acids are acquired, they combine to provide proteins the body tissues can use.

The liver is the center for breaking down needed proteins and sending the required amino acids into the blood. It constantly monitors and responds to the body’s protein needs. The liver is also responsible for processing and excreting the waste products that are produced as a by-product of protein metabolism.


Some people feel that consuming high-protein diets will help them lose weight faster and maintain muscle mass. The truth is that most people consume too much protein and place unnecessary strain on the body in doing so. The body will turn excess protein into fat, just as it will with carbohydrate and dietary fat. Excess protein in the diet will also cause more protein metabolism to occur, which produces waste products that must be disposed of.

Since ingested proteins are broken down and reassembled before getting used in the various parts of the body, eating foods containing certain amino acids does not necessarily mean that the body will use that amino acid in the form the individual intends it. For example, some people attempt to supplement with certain types of protein hoping to benefit from their health effects. This does not work the way the person intends it because the body controls protein metabolism by breaking down proteins and reassembling them with other amino acids to best satisfy the needs of the body.


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Post 4

Eggs are another good protein source. They are which is not only natural, but also cheap. If you are concerned about the fat, calories, or cholesterol in eggs, try using only egg whites or making scrambled eggs with one whole egg and two egg whites. One large whole egg contains 70 calories and 6 grams of protein. Just the white has 16 calories and 3 grams of protein. A good way to use eggs is in frittatas. There are a lot of good recipes on the web that use mainly eggs and vegetables and are very healthy.

Post 3

@saraq90 - Some food sources that I find easy to add to my daily diet are oatmeal (a cup has about 5.5g of protein), brown rice (a cup has about 4 grams of protein), and cubed cheese (makes for a very easy snack and 4 cubes have about 4 grams of protein).

But the best sources of protein for me to add to my diet, that are higher in protein, are beans (a half a can of most beans has approx 10-12 grams of protein) and tuna or salmon packets (these individual packets have 12-16 grams of protein).

Noticed I said packets or tuna or salmon! If you buy the packets you don't have to do the smelly process of draining, like you do with the cans of tuna or salmon. This makes it much nicer experience (less odorous experience) if you are preparing your meal around others!

Post 2

@aLFredo - I agree, protein is important, but a balanced diet is the key. So protein in moderation with a balance of all the other nutrients our body needs!

Easier said than done though, right?! I am learning about protein and all the good things it does for you and would like to add a little more to balance my own diet out.

The protein powders just seem expensive! Does anyone know of have any good natural foods that you would consider protein foods?

Post 1

I just read an article in one of the health magazines, and it talked about protein digestion as far as calories were concerned.

It turns out the proteins, fats, and carbohydrates are all, as this article describes broken down differently.

The biggest thing, I think, for dieters is that digestion itself of these items takes calories and it takes more calories to burn protein.

I think everything is good in moderation. Have a protein shake for breakfast, it helps you feel full, it helps you build muscle. But it just doesn't seem healthy to have one at every meal, no matter how much you work out!

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