Basic Nutrition Part 3, Proteins

We’ve now covered carbohydrates and fats, so the only macronutrient left to talk about is protein.  Protein (just like carbohydrates and fats) is a very important part of the human diet.  We get protein from various sources, such as meat, eggs, seeds and nuts.

Protein is comprised of amino acids.  The body requires approximately 20 amino acids in a specific pattern to make human protein.  11 of the 20 amino acids can be produced in the adult body.  9 amino acids cannot, therefore these are considered essential amino acids and we must get them from our diet.  In case you wanted to know, here are the 9 we can’t synthesize:

  1. phenylalanine
  2. valine
  3. threonine
  4. methionine
  5. tryptophan
  6. histidine
  7. isoleucine
  8. leucine
  9. lysine

Like carbohydrates, 1 gram of protein equals 4 calories.  However, when sufficient fats and carbohydrates are present in the body, we will not use protein as a source of energy.  Excess protein that is not used for building tissue or energy will be converted by the liver and stored as fat in the body tissues.  Under normal resting conditions, research suggests that 1 to 2% of our total fuel requirements are derived from protein.

So we can see that as we go about the bulk of our daily activities our bodies are either burning carbohydrate or lipids for fuel.  Protein becomes significant under survival situations.  This would look like exercising hard for 1 or two hours without eating anything, or during starvation, deprivation, or a very low calorie diet.  The human body is a marvelous machine and it has a great interest in keeping us alive.  So, during extended exercise without replenishment or starvation the body will cannibalize its own muscle tissue for emergency energy instead of body fat stores.

Seems odd doesn’t it?  Why would our body choose to convert muscle (which we use) instead of fat (don’t really use) for energy in an emergency preservation mode?  Well, I explained in the carbohydrate post that muscle tissue is the largest consumer of energy in the body.  Let’s say hypothetically that we’ve run out of food and we are trapped in our house (doomsday scenario).  We’ll live longer if we store more energy, and we’ll store more energy with a slower metabolism, and without a bunch of lean muscle tissue, we’ll have a lower metabolism.  Preservation tactics.  We see now why we need sufficient calories (via carbohydrate and fat) to keep our body out of preservation mode.  We prefer not to run on protein (via our body eating its own lean muscle tissue) for fuel.

During digestion, our body breaks down large molecules of proteins into the aforementioned amino acids.  These amino acids are the building blocks our body uses to grow and develop all our our tissues, muscles, skin, hair, nails, blood, and internal organs.  Next to water, protein is the most abundant substance in our body.

Recall there are 9 essential amino acids (building blocks).  Amino acids are tricky, and they won’t replace each other.  For us, this means that a daily balanced mixture of the essential amino acids is required.  An imbalance or ingestion of the 9 at different meals instead of simultaneously can lead to dietary insufficiencies.  Not all protein containing foods have all 9 amino acids.  Here’s an interesting fact about the amino acids, if we are consuming protein that is low in 1 of the 9 essential amino acids, the levels of the other 8 will drop to the level of the lowest one.  This would only happen in a chronic condition where the diet is imbalanced for 3 or 4 days, but it shows how important it is that each time we eat protein, we need to get all 9 amino acids.

Protein from animal sources contain all nine essential amino acids.  Plant sources of protein do not contain all nine.  Animal sources include ruminants (beef, bison, elk, lamb, etc…), poultry (chicken, duck, turkey, etc…), seafood (fish, mollusks, crustaceans), and eggs (typically from the chicken).  In addition to having amino acids we can’t produce, animal protein is rich in micronutrients, some of which we can’t effectively get from plants.  These include vitamin B12 and heme iron.  Eggs, and specifically the egg yolk, are rich in vitamins A, B12, D, E, brain healthy choline, omega-3 fatty acids, and eye healthy lutein.  Note: vegans and vegetarians have options!  I won’t go into detail here, and if you are a vegan or strict vegetarian you’ve likely done your homework and understand how to get your protein and those essential amino acids.  If you have questions, Chris, Annie, or I would love to talk with you.  

The minimum daily protein requirement is variable based on nutritional status, body size, and activity level.  It is recommended that 10-35% of the calories in our daily diet come from protein.  If your body composition consists heavily of muscle, you’ll be on the high side of that, if you are lean, the mid to low side.

Personally, I eat more protein than I estimate that I need.  The last few years I’ve really tried to balance my diet out by making sure that at every meal I have almost twice as many vegetables on my plate as the size of the protein I’m consuming.  This means if I’m eating a chicken breast I’m looking to have two chicken breasts worth of vegetables on my plate.

This concludes our 3 part series on the foundations of nutrition.  Did you enjoy learning about the macronutrients?  I truly enjoyed my research, boiling down all the information, and then attempting to concisely convey it to you all!  Hopefully you’ve found it helpful.

I’m curious to know if there are some other nagging questions about other topics you’d like to see a series of posts on?  Let me know in the comments or in person and I’d consider doing the leg work and writing about what I learn for you!


The O-Board Says…

A. EMOTM for 16 Minutes
Odd: 3 Deadlifts
Even: 10 Press (KB/DB)

B. Death by 10 Meters
(Previous death by 10)
Posted by: Stets