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How Protein Works

How Protein Works
Claire Muszalski
Writer and expert3 years ago
View Claire Muszalski's profile
If you’re working out regularly, trying to bulk up or trying to gain weight you’ve probably considered your protein intake - or at least been advised that protein can help you meet your goals. Protein is the OG supplement when it comes to muscle building and recovery. This article will explain exactly what protein is, how protein works, how much you need, and how you can increase your daily protein intake.Jump to:


What is Protein?

Protein is one of the three macronutrients we get from food, along with carbohydrates and fat. Macronutrients contribute energy in the form of calories - fat contains 9 calories per gram, while carbs and protein each contain 4 calories per gram. 

Protein does more than just provide us with energy though, it also helps repair and grow our body’s tissues, metabolic reactions, and daily functioning of our body’s systems. 

Proteins are chains made up of smaller building blocks called amino acids. The types of amino acids within a specific protein dictate its form and function. Protein is found in both animal and plant foods, though in highest concentration in animal protein sources like meats, poultry, fish, eggs, and milk. You can also get protein in plant-based foods like dried beans and peas, nuts, soy, and seeds. 


What are the Benefits of Protein and How Does it Work?

1. Growth and repair of lean muscle tissue

The primary benefit of protein when it comes to performance is the anabolic process of building muscle. Our muscles are always in a state of flux, breaking apart (muscle protein breakdown, or MPB) and rebuilding (or muscle protein synthesis, MPS). The balance between breakdown and synthesis dictates whether muscle tissue will be gained, lost, or balanced. 

Resistance training pushes our muscles to the limit, creating damage in the form of small tears in the muscle tissue. These tears need to be repaired by amino acids (protein building blocks), which help lead to growth of the muscle over time.1 Getting protein from our diet provides the necessary building blocks for growth and repair.


2. Improves body composition 

Body composition is based on the balance between fat mass and lean mass (muscle). Not only is protein key for building lean mass, it’s also essential during periods of weight loss. To lose weight, you have to burn more calories than you’re eating - which makes your body burn stored energy for fuel. 

Consuming protein to protect your muscles while still in a calorie deficit can help to target fat loss and improve body composition over time.2 Protein takes longer to digest than carbohydrates, so another benefit of protein is that higher protein diets can also keep you feeling more satiated to help limit calorie intake if you’re trying to lose weight.


3. Supports overall health

Protein has a number of important benefits in the body including the manufacturing of hormones, enzymes, messengers and immune-system components, as well as playing the main structural process of every muscle fibre.3 The amino acids that make up various proteins are therefore critical for the structure and regulation of cells. 

Protein also works to support gastrointestinal health. Protein increases glutamine intake which is shown to develop overall gut function as well as supporting the immune system.4 The amino acid cysteine (typically found in high amounts in whey) will also help to promote glutathione level in turn having a positive effect on the immune system.5


How Much Protein Do You Need? 

Healthy individuals need between 0.8-1.2g of protein per kg body weight per day for maintenance. If your goals are to increase mass and see other benefits, you need between 1.2 - 2.2 grams of protein per kilogram of bodyweight daily to encourage muscle growth.6

Women naturally have more fat mass than lean mass and require less protein overall than men. On average, women who are at a healthy weight should aim for 1.2g/kg per day and men should aim for 1.4g/kg per day.6

How To Increase Protein Intake 

You can increase your protein intake through your diet using the high protein foods in the list below, or by supplementing (adding to) your diet with protein shakes. 

Classification  Food  Grams protein per 100g food 
Meat  Chicken Breast  31g 
Turkey Breast  30g 
Pork Chops  30g 
Lamb Chops  26g 
Ground beef  26g 
Fish  Salmon  22g 
Sardines  25g 
Tuna  24g 
Mackerel  26g 
Nuts & Seeds  Chia Seeds  16g 
  Peanuts  24g 
  Almonds  21g 
Eggs  Whole eggs  12g 
  Egg whites  11g 
Dairy Products  Skim milk  3.5g 
  Greek yogurt  6g 
  Cheddar cheese  25g 
Soy Products  Soy beans  11g 
  Soy milk  4g 
  Tofu  16g 

There are a variety of protein shakes available to help increase your protein intake between meals. 

Whey protein shakes are the most widely available, and range in different levels of concentration/processing from isolate, hydrolysate, and concentrate. There are specific protein powders for those looking to lose weight or those who want to gain, and there are also vegan options like soy or plant based blend proteins. 

Take Home Message

There are many mechanisms and pathways on how protein works in the body, but all of them support health. Protein also works by supporting your muscles before, during, and after a tough workout at the gym. If you want to lose weight or gain mass, protein works to support lean tissue and can help keep you feeling satisfied. Another crucial benefit of protein is how it works to support the immune system and GI health to keep you functioning at your best.
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Our articles should be used for informational and educational purposes only and are not intended to be taken as medical advice. If you're concerned, consult a health professional before taking dietary supplements or introducing any major changes to your diet.

  1. Hoffman, J. R., & Falvo, M. J. (2004). Protein–which is best?. Journal of sports science & medicine3(3), 118. 
  2. Carbone, J. W., &Pasiakos, S. M. (2019). Dietary protein and muscle mass: translating science to application and health benefit.Nutrients11(5), 1136. 
  3. Wu, G. (2016). Dietary protein intake and human health.Food & function,7(3), 1251-1265. 
  4. Perna, S.,Alalwan, T. A.,Alaali, Z., Alnashaba, T., Gasparri, C., Infantino, V., … & Rondanelli, M. (2019). The role of glutamine in the complex interaction between gut microbiota and health: A narrative review. International journal of molecular sciences20(20), 5232. 
  5. Zavašnik‐Bergant, T., & Turk, B. (2006). Cysteine cathepsins in the immune response.Tissue antigens67(5), 349-355. 
  6. Table, M. (2005).Dietary reference intakes for energy, carbohydrate,fiber, fat, fatty acids, cholesterol, protein, and amino acids (Vol. 5, pp. 589-768). National Academy Press: Washington, DC, USA. 
  7. 2020.SELF Nutrition Data | Food Facts, Information & Calorie Calculator. [online] Available at: <> [Accessed 19 August 2020].
Claire Muszalski
Writer and expert
View Claire Muszalski's profile

Claire is a Registered Dietitian through the Academy of Nutrition and Dietetics and a board-certified Health and Wellness Coach through the International Consortium for Health and Wellness Coaching. She has a Bachelor of Science in Biology and a Master’s degree in Clinical Dietetics and Nutrition from the University of Pittsburgh.

Talking and writing about food and fitness is at the heart of Claire’s ethos as she loves to use her experience to help others meet their health and wellness goals.

Claire is also a certified indoor cycling instructor and loves the mental and physical boost she gets from regular runs and yoga classes. When she’s not keeping fit herself, she’s cheering on her hometown’s sports teams in Pittsburgh, or cooking for her family in the kitchen.

Find out more about Claire’s experience here.