The Importance of Protein in Our Diet

Why is it important to have enough protein not only for muscle gain but also for maintenance and weight loss?

Almost everyone knows that with building muscle it is important to enough protein to be able to do it. But what most people don’t know is the fact, that protein is important not only during the period of muscle gain, but it is just as important during losing weight and its maintenance as well! However, before I start to ramble about the reasons why, it is important to know what protein actually is. Protein is one of the three macronutrients our body receives from food. Proteins are made of amino acids, which in various combinations make different kinds of proteins in our body. These combinations of amino acids are almost everywhere in our body (in muscle, where we store up to 43% of the protein, but also in blood, skin, and other organs)[1].

Amino acids can be divided into two groups – essential and non-essential. Essential amino acids can’t be produced by our bodies and we have to get them via our food intake. In contrast to that, non-essential amino acids can be made by our body[2]. It is important to get all the essential amino acids for optimal health. We can find them in a complete range in animal-based products but we can find them, of course, in a plant-based diet as well. But with plant-based products, we have to be aware of various combinations of sources of protein so that we could get the complete range since plant-based sources don’t have the complete amino acids on their own.

In this article, I will mainly talk about the importance of protein during our journey to our fitness goals because, in my opinion, there is too much misunderstanding going on. But I will touch on other reasons why our body needs enough protein.

The Importance of Protein for Weight-loss and Weight Maintenance

As I already mentioned, protein is not important only during the muscle-gain period but equally as important during weigh-loss and maintenance. The first reason why is that protein is able to maintain and build muscle mass. You may be saying – but I don’t want to build muscle, I want to lose weight. Well, that’s nice, but if you don’t have enough protein in your diet and you are in a calorie deficit for a long time, your body doesn’t get rid of the fat only, it will get rid of the muscle as well. Muscles are metabolically very active (which means a body needs a lot of energy to maintain it) and if we don’t use the muscle and don’t supply our body with protein, which is needed for maintenance, we begin to lose it.

It’s because our body “thinks” economically and it doesn’t see a reason to maintain energetically demanding mass if it doesn’t have the tools to do it. So if we are in a calorie deficit and we don’t get enough protein, there is a high chance of losing muscle which will eventually lower our basal metabolic rate significantly more than if we just lost fat. And what more, we will feel and most probably be weaker and weaker.

The second reason to eat a higher-protein diet when in a calorie deficit or maintenance is the thermic effect of protein. That is the amount of ATP (adenosine triphosphate – a source of energy for bodily functions) which body has to release to be able to process food. The amount of ATP needed for different macronutrients varies – we need the most for processing protein, carbohydrates are second and we don’t need as much ATP for fats[3].

That is connected to the fact that a meal that is high in protein is able to satiate us more. That is not only because it takes longer to process protein, but there are many more mechanisms in our body that explain why protein can satiate our hunger better. If you are interested in the mechanisms, I will leave a study “Dietary protein and healthy body-weight” in the sources and you can look at it on your own[4]. If we are satiated, it is less likely that we will be hungry out of nowhere and eat everything in sight. Satiety also makes it easy to sustain the calorie deficit and therefore helps us lose weight.

It was proven that individuals who were on a higher-protein diet were able to lose more body fat (not necessarily more weight) and then maintain the goal weight easier than individuals with a lower-protein diet with higher carbs and fats ratio (but the same calorie deficit). Both of the diets were equally effective in losing bodyweight, but the group with consumption of 1,2 grams of protein for one kg of bodyweight had in the end better body composition (amount of muscle mass and body fat percentage) than a group with a diet of 0,8 grams of protein on one kg of bodyweight. Also, the group on a higher-protein diet was able to maintain a higher basal metabolic rate and therefore more easily maintained the goal weight[5].

It was also shown that a higher-protein diet helps with insulin regulation which influences the blood sugar levels and therefore influences our craving, feelings of fullness, and hunger[6]. But it is important to say, the even the group on a lower-protein diet wasn’t protein deficient. 0,8 grams on one kilogram of bodyweight is enough to maintain healthy body functions, it is just more beneficial to up the protein a bit during the weight-loss period. I will talk about it a bit later.

To sum it up, the amount of protein in our diet influences what exactly are we losing during being in a calorie deficit (whether muscle or fat), how satiated we feel, and how much energy our body is able to burn during food digestion.

Other important functions of proteins[7]

Protein is not only important for building and maintaining muscle mass, it has many more very significant functions in our bodies. As I said, various amino-acid combinations make different types of proteins. One of those combinations is for example enzymes that cause biochemical reactions in our bodies. Enzymes are very important for digestion, energy production, blood clotting, and muscle contractions.

Another combination of amino-acids is hormones. All hormones are not made of protein but most of them are. These hormones act as a messenger between cells and tissues and help our body function properly. These hormones are for example insulin or glucagon.

Some types of protein are so-called “structural proteins”, which help maintain hair, skin, tendons, bones, and organs their elasticity, shape, and rigidity. These proteins are for example keratin, collagen, or elastin. As I said, they are not important only for our hair and nails, but they are very significant for the elasticity of our organs, such as the lungs and uterus, same as the rigidity of our bones.

Protein has many other functions such as maintaining proper pH (for example hemoglobin which maintains the proper concentration of acid and alkaline substances in the blood), balancing fluids (for ex. Albumin and globulin which are proteins in our blood that attract or retain water and their deficiency can lead to water retention in the body), powering up the immune system (some of the proteins help our body fight bacteria and viruses), transporting and storing of nutrients (for ex. Hemoglobin again which carries oxygen) and last but not least protein is, of course, a source of energy because one gram of protein has four calories for our body to use.

How much protein do we need?

That’s a question for which you get a different answer every time you ask someone else. According to studies, it is, however, a range between 0,8g-2,67g per kg of bodyweight[8]. So in the grand scheme of things, it depends on our lifestyle – if we are very active, it is always better to have a higher intake of protein than the bottom limit, but if we have a sedentary job, we don’t exercise and don’t have an ambition in building muscles, 0,8g per kg is enough for our body to function properly. But of course, there are periods of our lives, when it is ideal to bump up the protein intake a bit even if we aren’t professional athletes.

First, as we already discussed, it is good to do it when in a calorie deficit as it helps us maintain or even gain muscles, it satiates us more and has a higher thermic effect. Second, it is better to slowly increase our protein intake with age as it is common to lose muscle when getting older. And third, it is during an illness, when it is not only easier to lose muscle (as we don’t use it that much) but also proteins help us make antibodies which will help us fight the disease.

But of course, as it is with all, everything with reason. Even though having protein intake under 0,8 grams per kg of bodyweight truly is not ideal for optimal health, there is no rule “the more, the better”. Excessive protein consumption can in fact cause some health problems as well (when we consume regularly and long-term more than 2,8 grams of protein per kg of weight – but of course, even there we are exceptions). It can cause problems with kidneys because when the body has a lot of protein, it can’t process it so it eliminates it through urine. However, if there is a lot of protein, kidneys are not capable of processing it as well, and it can damage them. Another problem it can cause is a problem with body hydration and electrolyte balance, nutrients absorption, and last but not least it can cause digestion issues as it is difficult for the body to digest it[9].

Dietary supplements

The best way of eating enough protein is of course through whole-foods. But if there comes a time, when we don’t know how to include more protein sources into our diet, dietary supplements in form of protein powder may be a good help. We can add it not our oatmeal, pancakes, cakes, or just drink it like a shake. Women, don’t worry, you truly won’t become a bodybuilder if you drink a protein shake, I promise you that. That takes an enormous amount of effort and time, drinking a protein shake is really not doing the trick. Supplementation is of course not necessary, that’s why it is called a supplement. But for someone who has a problem getting enough protein through their current diet, it is a good way to easily bump up the amount.

Don’t underestimate it

Now, I am not saying that you should eat pounds of meat and drink liters of protein shakes on top of it, not at all. That is not the point. I just wanted to point out (pun not intended) why it is good to keep an eye on our protein intake on a journey to our fitness goals and I don’t know…maybe it will help someone. Sometimes it is way too easy to let ourselves get carried away by carbs and fats – they are delicious! But it is very important not to underestimate protein as well…I mean, try and see for yourself.

[1] British Nutrition Foundation. Protein. Online:

[2] MedlinePlus. Protein in diet. Online:

[3] Westerterp-Plantenga, M.S., Nieuwenhuizen, A., Tomé, D., Soenen,S. and K.R. Westerterp. “Dietary Protein, Weight Loss, and Weight Maintenance.” The Annual Review of Nutrition (2009): 29: 21-41

[4] Westerp-Plantenga M.S., Lemmens S.G., Westerp, K.R. “Dietary protein – its role in satiety, energetics, weight loss and health.” British Journal of Nutrition (2012), 108: 105-112

[5] Westerp-Plantenga M.S., Lemmens S.G., Westerp, K.R. “Dietary protein – its role in satiety, energetics, weight loss and health.” British Journal of Nutrition (2012), 108: 105-112

[6] Munsters, M.J.M., Sairs, W.H.M. “Body Weight Regulation and Obesity: Dietary Strategies to Improve the Metabolic Profile.” The Annnual Review of Food Science and Technology (2014), 5:39-51

[7] Van de Walle, Gavin. “9 Important Functions of Protein in Your Body”. June 20, 2018.

[8] Simmons, E., Fluckey, J.D., Riechman, S.E. “Cumulative Muscle Protein Muscle Protein Synthesis and Protein Intake Requirements.” The Annual Review of Nutrition (2016), 36:17-43

[9] Westerterp-Plantenga, M.S., Nieuwenhuizen, A., Tomé, D., Soenen,S. and K.R. Westerterp. “Dietary Protein, Weight Loss, and Weight Maintenance.” The Annual Review of Nutrition (2009): 29: 21-41