The Importance of Protein in the Body

Two eggs over easy on a two pieces of toast for importance of protein in the body main header image.

In the realm of nutrition and wellness, with all of the “gluten-free”, “low-carb” diets – you don’t often hear about restricting protein. In fact, it’s quite the opposite- how is it that we can increase our protein intake? That’s because protein is vital not only for physiological reasons, but also for our mood, satiety, and weight. This post will explore the importance of protein in the body. 

By increasing our awareness on all the benefits protein has to offer, we can figure out where we have room to improve. Let’s discuss the latest research regarding protein intake in hopes to enhance our well-being. 

Why is Protein Important?

Our body needs amino acids, the building blocks of protein, to regulate many bodily processes. Unlike carbohydrates and fat, protein is not stored in the body for later use. Therefore, we must consume it from our diet. When we eat more protein than our body needs, it will be broken down and used for energy, excreted, or stored as fat. 

Proteins regulate many bodily processes – they act as messengers, help to create hormones and enzymes, maintain fluid balance, and form most of our body’s structures (such as our skin, muscles, organs and bones). 

Our bodies are in a constant state of turnover – cells are constantly creating and destroying proteins. This is especially true during periods of critical illness, breastfeeding and pregnancy – where the turnover increases,  thus elevating our needs.

Difference in Quality of Protein Sources

Biological value is a measurement of how well the body uses protein when consumed in the diet (1). A high value would contain a large supply of amino acids – in total, there are 20 of them.

Of those, there are 11 essential amino acids, which means the body cannot produce them and we must consume them from the diet. Foods from animal products are considered the richest sources of these amino acids. 

All plant foods contain all 20 amino acids – but in less optimal amounts as compared to animal products (2). For example, rice is considered to be too low in lysine and thus labeled as an “incomplete protein”. 

It used to be said that for vegetarians to obtain adequate amounts of protein, each meal should be “balanced” and contain a grain and a bean. More recent research has shown this is not the case – vegetarians just need a variety of sources throughout their day.

In fact, the Academy of Nutrition and Dietetics state that a well-planned vegetarian or vegan diet can help prevent certain diseases, such as heart disease, Type 2 Diabetes, hypertension, and certain cancers (3). 

In Western countries, research has demonstrated that vegetarians often meet the recommended daily amounts of protein with even just a slightly varied diet. Therefore, plant foods can be good sources of protein as long as you’re choosing a variety. 

Protein Sources from Animal Products

protein from animal products

Plant Based Protein Sources

plant based protein sources

How Much Protein Do You Need Per Day?

The recommended daily allowance (RDA) for protein is 0.8 grams per kilogram of bodyweight. For a women who weighs 150 pounds, this would amount to 60 grams of protein per day (divide your weight by 2.2 to calculate kg). This number is the absolute minimum requirement for the average adult.

Protein needs increase as adults get older, and for people who exercise regularly. The American College of Sports Medicine recommends 1.2-1.7 g/kg/day for those aiming to increase muscle mass. 

Can Protein Help You Lose Weight?

Protein is a very important nutrient for both weight management and weight loss. The body uses more calories to metabolize protein as compared to carbohydrates and fats. It also helps to keep us fuller for a longer period of time, thus decreasing hunger cues or mindless snacking.

Incorporating an adequate amount of protein into your diet, preferably at each meal, will help promote weight loss by increasing satiety and therefore, decreasing snack or potentially promoting less intake at meals. 

Consuming a high protein diet while trying to actively lose weight is important to preserve muscle. This is helpful for weight maintenance because increased muscle tissue increases our metabolism – even at rest. 

Studies suggest that a vegan diet can help promote weight loss (4). However, being mindful of adequate protein intake is vital as it can be a challenge consuming enough protein per day. 

How Much Protein Should I eat at one Meal?

There has been much debate on how much protein you should consume at each meal, based on how our bodies absorb it.

Most research shows that you can consume high amounts of protein at a meal, that there is no limit – our bodies will just take a longer time to absorb it. However, all of the protein consumed may not be used for building muscle. If protein is consumed in excess, it can also be stored as fat. 

When it comes to metabolizing protein for muscle growth, how much your body can use at a time may vary based on the composition of a meal, a person’s age, their physical activity level, and amount of lean body mass. It has been proposed that muscle synthesis is maximized in most individuals consuming 20-25 grams of high-quality protein (5). Anything greater is thought to be used for energy or trans-aminated to form other compounds. 

Also, different protein sources have different absorptions rates which can also cause variations in muscle protein synthesis. For example, whey protein has a high absorption rate compared to other sources of protein. 

It’s still unclear which protein sources reign supreme, whether they really have an effect on our muscle gains, and whether consuming greater than 25 grams of protein will lead to additional benefits. Determining a maximum amount of protein per meal used for muscle protein synthesis has been very challenging for researchers. 

Most recent recommendations encourage eating high protein meals consisting of 20-25 grams of high-quality protein spread throughout 3-4 meals per day, as it can help with digestion and absorption. It has been shown that consuming a balanced protein distribution may be a more practical way for adults with inadequate protein intakes to achieve a higher total protein intake (6). 

Does Protein timing matter for Workouts?

Newer research has shown that the so called “anabolic window”, or consuming protein immediately after a workout, is no longer essential for muscle growth and repair (7). 

Brad Schoenfeld is an exercise scientist whose research suggests that as long as you eat protein within a several hour window of your workout, before or after, will result in the same results. 

Overall protein consumption seems to be of more significance than the timing – in line with the above recommendation of evenly distributing protein throughout the day.

What Happens When You’re Deficient in Protein?

With the many functions of protein comes many symptoms when you’re deficient. While very uncommon in most Western countries, signs of a protein deficiency can include:

  • Brittle hair and nails
  • Feeling weak or hungry
  • Mood changes or trouble thinking
  • Edema, or fluid imbalance
  • Loss of muscle mass
  • Impaired immunity

A diet high in protein can have many health benefits, including assisting with weight maintenance and loss, greater muscle mass, increased satiety, improved mood, decreased risk of infections, among many others! 

Ensure you are at least meeting the recommended daily allowance by evenly distributing protein throughout your day, and being mindful of the quality of protein sources. If you are vegetarian or vegan, consuming a variety of different sources will help to meet your needs! 

If consuming high protein at every meal is difficult, read my post 10 high protein vegetarian snacks for ideas to sneak in some additional protein. 

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