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Protein Facts for Nutrition

This blog post was created to outline the facts and functions of protein and how it affects the body.

Firstly, let's start with the functions of protein:

  • Main function of protein is for tissue growth and repair. Protein is an essential component of all body structures, especially muscle, skin and connective tissue.

  • Regulation of metabolism. Enzymes in protein play a role in facilitating biomechanical reactions including energy production and digestion.

  • Muscle contraction. Actin and myosin are contractile proteins within the muscle that allow muscle movements for everyday activities.

  • Immunity. Protein is responsible for formation of white blood cells and immune proteins such as antibodies.

The simplest form of protein is called amino acids. When protein is digested, it is broken down into amino acids and that's when they can be used. There is no specific storage for amino acids within the body, unlike carbohydrates. This means that protein needs to be replenished daily. This is a reason why carb intake doesn't need to be too high daily especially for weight loss, however, protein intake should never drop even if we're trying to lose weight. This is because we need to replenish protein sources daily.

When it comes to amino acids form protein, there are a number of amino acids that are considered essential and some are considered non-essential. Essential meaning that they need to be consumed on a regular basis as these amino acids are not produced by the body. Non essential does not need to be consumed as much as they are produced naturally by the body.

Here is a list of the proteins:

Essential - The 9 essential amino acids are: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.

Non essential - The 12 non essential amino acids are: alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, proline, serine, and tyrosine.

Sources of protein are:

When it comes to protein, we classify them as first class (containing all essential amino acids) or second class (containing only some essential amino acids)

First class:

  • Eggs, all dairy products, all meats, all fish and all poultry. Plant sources are anything soy or soybean based such as tofu, tempeh and soy milk. Quinoa is also a good source although it is high in carbohydrates.

Second class:

  • Gelatine, legumes, nuts and vegetables such as broccoli, spinach, asparagus and mushrooms. Grains and seeds are also sources.

Most sources of essential amino acids come from animal sources, other than soy products. However, this doesn’t meat we need to over consume meat just to get our protein up. an over consumption of meat and animal fats can be very high in cholesterol and saturated fats. As we see more and more people turn to plant based diets, we can still get enough protein from plant based diets. Soybeans and soy products provide all essential amino acids. Outside of that, we can protein pair as we eat so that two foods containing different essential amino acids combine to give us all essential amino acids.

Some example are eating grains with dairy (multigrain bread with cheese). Eating grains with legumes (brown rice and bean dishes). Eating seeds and legumes (adding pumpkin seeds or sunflower seeds to dishes containing beans such as chickpeas, lentils or beans).

So, protein is an essential part of a daily diet. When we think about health and weight loss, protein needs to consumed daily at a moderate to high amount taking into consideration how much we are exercising.

As mentioned above, the functions or protein are mainly to repair tissues in the body and also for immunity. Both are very important to daily life and health. The more we exercise for health and weight loss the more our bodies need protein to be able fully provide its functions for repair and immunity. Protein also has the function to provide satiety (feeling of fullness) as it is harder to breakdown compared to the other two macronutrients. This can help stop cravings for food later in the day or late at night.

When we talk about protein intake, general rule of thumb is 0.8kg per kg of body weight. Meaning if someone is 100kg their daily protein intake should be around 80g. If that person is training and moderately active a couple times a week they should increase their protein intake to around 1g to 1.2g per kg body weight. Using the same person, that means their daily protein intake should be around 100g to 120g. As a professional athlete or weightlifter, it could go as high as 1.8g to 2.2g per kg. But that’s not the general population.

So to conclude, protein is essential for daily health and body function. For people who exercise and are aiming for weight loss, protein can help with recover and providing satiety. I hope we all have a better understanding on protein and its benefits for health and weight loss and for more in depth info on weight loss and how protein works, check out the Understanding How Weight Loss Works blog.