Why Protein Is Important In Your Diet

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Most diets that have been used with great success over the last several decades have one thing in common: they all acknowledge that protein is a critical part of losing weight and maintaining or increasing lean muscle mass. 

Regardless of whether it is a plant-based vegan diet, an all-meat carnivore diet, or something completely different, they almost all agree that protein is important in your diet.

This article is going to cover why it is not a bad idea to consider protein the most important macronutrient, especially if you are looking to lose weight and/or build muscle. 

The Difference Between Protein, Carbohydrates and Fats

Before we dive into why protein is important, let’s first understand a little bit about why protein is different from carbohydrates and fats. 

The first difference is that protein is the only “stored” macronutrient that is primarily stored for “structure and function” and not for energy. Meaning that the body does not store protein for the main purpose of using it for energy, but rather for building/repairing tissue (like muscle), creating enzymes, or building the immune system or transporting things around the body.

While the body CAN use protein for energy, that is definitely not its primary purpose. 

Without protein, you would have no organs, bones, skin, or anything that requires building blocks to sustain itself. Protein is essentially constantly at work in your body. They’re construction workers that don’t take time off.

Carbohydrates and fats, while they provide some structure and function, are also primarily used for energy and the body can pretty readily manufacture them out of other things. Whereas the body cannot easily manufacture protein from other sources.

Additionally, protein is what is known as an essential macronutrient. The term essential in this context means the body has to get protein through the diet, it cannot make protein on its own. Protein is made up of amino acids (AA). 

Graphic showing amino acids convert to peptides which converts to protein | Macros Inc

The 9 Essential Amino Acids

There are 20 amino acids in total needed by the human body. This can be broken down into subcategories of essential and nonessential amino acids. There are 9 essential amino acids, meaning the body cannot make those 9 by itself and must consume them in the diet.

The 9 essential amino acids are:

  • Leucine
  • Isoleucine
  • Valine
  • Lysine
  • Tryptophan
  • Threonine
  • Methionine
  • Phenylalanine
  • Histidine

This is important as you’ll need all 9 to regulate many bodily functions. In addition, you’ll need all 9 to maximize muscle retention or muscle growth. This is why animal protein sources are generally superior to plant sources.

They generally yield higher absolute protein amounts as well as possessing all 9 essential amino acids making them a complete protein. Most plant sources are incomplete meaning they lack at least 1 or more of these essential amino acids with some exceptions like soy.

But even when comparing equal amounts of complete protein, animal sources, compared to plant sources,  seem to be superior for muscle building

Graph showing the differences in plant and animal based protein | Macros Inc
The number of servings needed to reach 20g of protein for specific types of food

Consuming enough protein is important not only for weight loss (more on that in a minute) but it is also critical for overall health. Here are a few reasons why adequate protein intake (regardless of everything else) is important:

  • Optimal health and bone density.
  • Improves sleep quality
  • A high thermic effect of food meaning you’ll burn extra calories from digestion.
  • Proper Satiation as you’ll need a baseline of protein to be full. In addition, protein is generally more filling than carbs/fat especially in people who undereat protein.
  • Optimal muscle retention/building based on energy balance.

This is why at Macros Inc, we make sure clients eat the correct amount of protein for their needs. It’s arguably the most important macro to optimize to feel great and look your best. It’s not merely a nutrient bodybuilders love to talk about to build muscle.

Why Is Protein Important For Weight Loss?

Many people think of protein as a muscle building nutrient, but it’s just as important for weight loss if not more important. Of the three macronutrients, protein may very well be the most important to optimize.

During a diet, you are eating in a caloric deficit, which means that you are burning more energy than you are taking in. This puts the body in a state of catabolism, which means that the body is likely going to utilize tissue, including muscle to provide energy. 

Interestingly, consuming protein results in an anabolic signal that tells the body to try and spare as much muscle as possible during periods of calorie deficits.  By consuming protein, you keep muscle turnover at a favorable balance. This helps you maintain muscle mass and lose body fat while you are losing weight. 

In addition, protein is the most energetic to digest meaning your body burns the most calories from digesting it compared to carbs and fat. The term, “the meat sweats” has much truth to it. Your body also burns more from digesting mixed meals which must contain protein.

Another benefit of protein is satiety. On average, most protein sources are more filling than many carb and fat sources. Your body needs a certain amount of protein to maximize satiety. Anyone not used to eating enough protein will know just how filling it can be.

Sources of Protein

Here are a list of recommended protein sources that are high in protein while being low in calories: chicken breast, chicken thigh, fish, seafood, turkey, turkey sausage, lean beef (lean cuts w/ round or loin in their names), ground turkey, ground beef (at least 90% lean), pork tenderloin, lean deli meats, egg whites, fat free Greek yogurt, cottage cheese, protein powder (whey or casein is best), game meat, organ meat.

What 145g of protein looks like in a day image | Macros Inc

Most people will have to eat one of these sources at every meal or supplement with a protein powder/drink to meet their protein targets.

As for protein supplements, the 2 main types are whey and casein, both of which are made from dairy. Minimal lactose is in both, but if intolerance occurs, feel free to use something like egg protein.

As for whey and casein, whey is considered a faster protein meaning it spikes amino acids into the blood quicker, but at a less sustained rate. Casein spikes amino acids weaker, but at a more prolonged rate. Research shows there isn’t much net difference, so don’t fret too much about which one to get.

There are also plant based sources of protein that individuals who follow a plant-based diet can utilize. These include foods such as: soy beans, tofu, chickpeas, lentils, quinoa, black beans, nuts and seeds (e.g. almonds and sunflower seeds) also have protein but are very energy dense sources of protein. 

There are also plant based protein powders that utilize mixes of plant proteins (such as rice and pea) to create complete amino acid profiles. 

To figure out how much protein per day is right for you, use our Macro Calculator.


Of all three macronutrients, protein is often the one most focused on because it can be the biggest lever you can pull in your diet to affect change in body composition. This is because protein has the greatest effects on lean body mass and satiety of the three macronutrients.

As such, it is often considered the most important macronutrient, especially for people trying to lose weight and/or build muscle.

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