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Protein: A Comprehensive Guide

16 Mar, 2024
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Top Ten FAQ's - Protein

What is protein?

Protein is a macronutrient made of amino acids that are essential for the body's structure, function, and regulation of tissues and organs.1

Why do we need protein?

Proteins are vital for building and repairing tissues, making enzymes and hormones, and building bones, muscles, cartilage, skin, and blood.2

How much protein do I need?

The Recommended Dietary Allowance (RDA) for protein is 0.8 grams per kilogram of body weight per day for adults. However, protein needs may vary depending on activity level, body type, age, and other factors.3

What are the best sources of protein?

High-quality protein comes from animal sources like meat, fish, eggs, and dairy products, as well as plant sources including beans, lentils, nuts, and whole grains.2

Can you get enough protein from a vegetarian or vegan diet?

Yes, a well-planned vegetarian or vegan diet can provide all the necessary protein through plant-based sources such as legumes, grains, nuts, seeds, and soy products.4

What is a complete protein?

A complete protein contains all nine essential amino acids in sufficient amounts. Animal proteins are complete, as well as some plant-based options, like soy.5

What are the signs of protein deficiency?

Signs of protein deficiency can include oedema, muscle wasting, hair loss, brittle nails, skin rashes, and an increased risk of bone fractures.6

How does protein affect weight loss?

Protein may help with weight loss by increasing satiety, reducing appetite, increasing energy expenditure, and helping preserve lean muscle mass during calorie restriction.7

Is protein important for athletes?

Yes, athletes may need more protein than non-athletes to support muscle repair, growth, and overall recovery.3

What are BCAAs, and why are they important?

Branched-chain amino acids (BCAAs) are three essential amino acids (leucine, isoleucine, valine) that you must obtain from your diet. BCAAs are particularly important for muscle protein synthesis and recovery.8

Proteins, the building blocks of life, are an essential component of every cell in our bodies.

Understanding the role of protein can help you make smarter dietary choices and lead a healthier lifestyle. So let’s dive into what protein is, why it’s vital, and how to ensure you're getting enough. 

What is Protein? 

At its core, protein is a macronutrient composed of amino acids. Twenty different amino acids (9 essential and 11 non-essential) link together in various ways to form a protein. These chains of amino acids fold into complex shapes and form the foundation for muscle, skin, enzymes, cells, and hormones.2

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The Importance of Protein 

Proteins are involved in nearly every function and chemical reaction that occurs in your body. They repair and maintain body tissues, including muscle repair after exercise.9 Proteins are also instrumental in creating enzymes that power countless chemical reactions within the body and haemoglobin that transports oxygen in your blood.10

Daily Protein Requirements 

The Recommended Dietary Allowance (RDA) for protein is 0.8 grams per kilogram of body weight per day. However, this is the minimum amount needed to prevent deficiency, not necessarily the optimal amount for health, particularly for active individuals or those looking to build muscle mass. Athletes or people engaging in regular intense exercise may need 2 grams per kilogram of body weight or more of protein per day.3

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Quality of Protein 

Not all proteins are created equal. 'Complete proteins' contain all nine essential amino acids our bodies cannot produce on their own. Animal-based foods like meat, dairy, and eggs typically contain complete proteins, while most plant-based proteins are ‘incomplete,’ lacking one or more essential amino acids. However, combining different plant foods can provide a complete amino acid profile.5

Getting Enough Protein on a Plant-Based Diet 

Contrary to popular belief, a vegetarian or vegan diet can meet protein needs with careful planning.4 Legumes, nuts, seeds, whole grains, and soy products are excellent protein sources. Quinoa, for example, is considered a complete plant-based protein, while tofu is a versatile protein-rich soy product.

The Role of Protein in Weight Loss 

High-protein diets may aid in weight loss by promoting satiety, which may lead to reduced calorie intake. Protein also has a higher thermic effect compared to fats and carbohydrates, meaning your body uses more energy to digest it, which may also aid in weight management.7 However, carbohydrates and fats are still a necessary part of a well-balanced diet, no matter your weight loss goals.

Too Much of a Good Thing? 

While protein is essential, it's possible to have too much. In some cases, excessive intake of protein can lead to digestive issues, kidney strain, and, in severe cases, an increased risk of heart disease.11 Therefore, it's essential to balance protein intake with other nutrients.

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Protein for Athletes 

For athletes, protein is especially important. Research shows that protein helps repair muscle fibres that break down during exercise and provides the necessary components for muscle growth and recovery. Post-workout protein, coupled with carbohydrates, can enhance muscle repair and growth.12

BCAAs - The Essential Trio 

Branched chain amino acids (BCAAs), comprising leucine, isoleucine, and valine, are three crucial amino acids for muscle protein synthesis and recovery. BCAAs are also vital to disease prevention. They’re particularly popular among athletes and bodybuilders for their potential muscle-building benefits.8

Protein Absorption and Digestion 

Our body breaks down consumed protein into amino acids, which are then absorbed and utilised. Factors that affect protein absorption include the type of protein, the presence of other nutrients, and individual digestive health.13

Grilled salmon with green beans and lemon, in line with Lily & Loaf's ethos for balanced nutrition.

Cooking and Protein Quality 

Cooking can denature proteins, altering their structure. While this makes them easier to digest, it rarely impacts the nutritional content significantly. However, overcooking may reduce the availability of some amino acids, so it’s best to avoid charring or overcooking protein sources.14

Supplementing with Protein 

Protein supplements, such as whey or plant-based powders, may be beneficial for those struggling to meet their protein needs through diet alone, such as vegans or people with high protein requirements. However, it’s always best to seek protein from whole food sources when possible.

Protein plays a critical role in our health, from building and repairing tissues to making enzymes and hormones. Whether you're an athlete, someone trying to lose weight, or just aiming for a balanced diet, it’s important to consume enough high-quality protein every day. By understanding your body's protein needs and the best sources to meet them, you can ensure that this powerful nutrient is a cornerstone of your healthy eating plan.



  1. National Cancer Institute. Protein.
  2. MedlinePlus. What are proteins and what do they do?
  3. Wu G. Dietary protein intake and human healthFood Funct. 2016;7(3):1251-1265. doi:10.1039/c5fo01530h
  4. Mariotti F, Gardner CD. Dietary Protein and Amino Acids in Vegetarian Diets-A ReviewNutrients. 2019;11(11):2661. doi:10.3390/nu11112661
  5. Hertzler SR, Lieblein-Boff JC, Weiler M, Allgeier C. Plant Proteins: Assessing Their Nutritional Quality and Effects on Health and Physical FunctionNutrients. 2020;12(12):3704. doi:10.3390/nu12123704
  6. UCLA Health. Are you getting enough protein? Here’s what happens if you don’t.
  7. Moon J, Koh G. Clinical Evidence and Mechanisms of High-Protein Diet-Induced Weight Loss. J Obes Metab Syndr. 2020;29(3):166-173. doi:10.7570/jomes20028
  8. Neinast M, Murashige D, Arany Z. Branched Chain Amino AcidsAnnu Rev Physiol. 2019;81:139-164. doi:10.1146/annurev-physiol-020518-114455
  9. Vliet SV, Beals JW, Martinez IG, Skinner SK, Burd NA. Achieving Optimal Post-Exercise Muscle Protein Remodeling in Physically Active Adults through Whole Food ConsumptionNutrients. 2018;10(2):224. doi:10.3390/nu10020224
  10. LaPelusa A, Kaushik R. Physiology, proteins. In: StatPearls. StatPearls Publishing; 2024.
  11. Delimaris I. Adverse Effects Associated with Protein Intake above the Recommended Dietary Allowance for AdultsISRN Nutr. 2013;2013:126929. doi:10.5402/2013/126929
  12. Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exerciseJ Int Soc Sports Nutr. 2017;14:20. doi:10.1186/s12970-017-0177-8
  13. Dallas DC, Sanctuary MR, Qu Y, et al. Personalizing protein nourishmentCrit Rev Food Sci Nutr. 2017;57(15):3313-3331. doi:10.1080/10408398.2015.1117412
  14. Zhang Y, Zhang P, Peng H, et al. Effects of Cooking Processes on Protein Nutritional Values and Volatile Flavor Substances of Silver Carp (Hypophthalmichthys molitrix). Foods. 2023;12(17):3169. doi:10.3390/foods12173169