Discussions about protein are no longer confined to the weights room. It is a hot topic, so much so that the food industry has caught onto this and is adding it to all sorts of ultra-processed foods hoping to appeal to a health-conscious crowd. This guide to protein takes a closer look at this macronutrient so you can understand what all the fuss is about.
Understanding Protein: The Building Blocks of Life
Protein is a vital macronutrient, needed to maintain and build tissues in your body. It's composed of amino acids, often referred to as the building blocks of life. Among the 20 different amino acids, some are produced by our bodies, while others, known as essential amino acids, must be obtained through our diet.
The Benefits of Prioritising Protein in Every Meal
Satiety & Weight Management
As protein takes longer to digest compared to carbohydrates and fats, it can help you feel fuller for longer. Protein intake also influences the release of hormones involved in appetite regulation, reducing hunger and increasing satiety by regulating hormones such as ghrelin (hunger hormone) and peptide YY (signals you are full). This reduces the likelihood of overeating and helps you control your overall caloric intake.
Metabolic Boost
The thermic effect of food refers to the energy expenditure required for digestion, absorption, and metabolism of nutrients. Protein has a higher thermic effect compared to carbohydrates and fats, meaning the body burns more calories when processing protein. Approximately 20-30% of the calories from protein are used up in the digestion and processing, compared to 5-10% for carbohydrates and 0-3% for fats.
Improved Blood Sugar Regulation
When a client tells me they need help with their sugar cravings, protein intake (especially in the morning) is one of the first things we look at. Combining protein with carbohydrates and fats in balanced meals prevents the energy crashes and hunger pangs often associated with high-carb meals. Protein helps to slow the absorption of glucose into the bloodstream helping to maintain stable blood sugar levels. This is particularly important for those with insulin resistance or diabetes.
Prevents Sarcopenia
Sarcopenia is the gradual loss of muscle mass and strength that is associated with ageing. This can decrease your mobility, increase the risk of falls, and reduce quality of life. Protein is essential for slowing the rate of muscle loss, maintaining your muscle mass, and promoting muscle repair and growth. Older adults have higher protein needs to counteract their reduced ability to build muscle in response to protein intake and exercise, and so increasing protein intake is very important. Eating plenty of protein (read on for recommended amounts), alongside resistance training, can prevent sarcopenia and support your muscle health.
Functions of Protein in the Body
Muscle Development and Repair
Protein provides the amino acids needed to build muscle tissue. Stress and minor damage to muscles during physical activity, particularly resistance training, triggers muscle protein synthesis when there is sufficient dietary protein intake. New proteins are formed to repair and grow muscle fibres, increasing muscle size and strength. This is why protein intake after your workout is important for recovery and to prevent muscles soreness and fatigue.
Hormone Production
Hormones are chemical messengers in your body, and many of these are made from proteins. These proteins help to regulate physiological processes such as digestion, metabolism, growth, and reproductive functions.
Enzyme Function
Enzymes, which are proteins, are catalysts in over 5,000 biochemical reactions occurring in the body to keep us alive.
Immune Function
Antibodies are proteins that recognise and bind to foreign pathogens like bacteria and viruses, marking them for destruction by other immune cells. Proteins are also involved in the production of other immune system components, for example cytokines and complement proteins, which help coordinate the body’s immune system.
Structural Support
Proteins provide structural support to cells and tissues to maintain cell shape and enable cell movement. Protein such as collagen and keratin are also key components of connective tissues, skin, hair, and nails.
Transport and Storage
Proteins function as transporters, carrying substances such as fats and oxygen throughout the body. Whilst some proteins are storage molecules - for example ferritin stores iron so it is available when the body needs it.
Cell Signalling and Communication
Receptor proteins embedded in cell membranes initiate cellular responses depending on what they detect from the external environment. This maintains homeostasis (balance) in the body by responding to changes. Proteins also influence cellular response by transmitting signals from the cell surface to the interior, initiating gene expression, metabolism changes, or cell division.
Healthy Whole Food Sources of Protein
Your nutritioanl needs can be met with healthy protein sources such as:
Lean Meat: Chicken, turkey, and lean beef.
Fish & Seafood: Salmon, tuna, white fish, and shellfish.
Eggs
Dairy: Greek yoghurt, cottage cheese, and milk.
Plant-Based Protein: Pulses (e.g., lentils, chickpeas), quinoa, and tofu.
Nuts & Seeds: Almonds, chia seeds, and hemp seeds.3
Recommended Protein Intake
Your age and activity level influences the amount of dietary protein you need to meet your needs:
Sedentary Adults: The UK recommended daily allowance is 0.8g / kg of body weight (BW) / day.
Active Adults: For those who lift weights regularly or are training for running or cycling events, the recommended intake is 1.2 - 1.7g / kg BW / day.
Older Adults (65+): Increasing protein intake to 1.6 - 1.8g / kg BW / day can help to reduce age-related muscle loss. There is evidence to show increasing protein intake is beneficial from 55 years.
Athletes: Endurance athletes should aim for the lower end of 1.4 - 2.0g / kg BW / day, while power and strength athletes may benefit from the higher end of the range. Despite many contradictory recommendations, a 2018 meta-analysis by Morton et al concluded that exceeding 1.6g/kg BW / day does not show additional muscle building benefits for bodybuilders.
Conclusion
Protein is a cornerstone of a balanced diet, especially for those focused on fitness and health. By ensuring a high enough intake from varied sources, you can support your body's needs and improve your athletic performance.
If you would like personalised advice and to learn more about incorporating protein into your diet, feel free to book a free call with me.
References
1. Moon, J., & Koh, G. (2020). Clinical Evidence and Mechanisms of High-Protein Diet-Induced Weight Loss. Journal of obesity & metabolic syndrome, 29(3), 166–173. https://doi.org/10.7570/jomes20028
2. Rogeri, P. S., Zanella, R., Jr, Martins, G. L., Garcia, M. D. A., Leite, G., Lugaresi, R., Gasparini, S. O., Sperandio, G. A., Ferreira, L. H. B., Souza-Junior, T. P., & Lancha, A. H., Jr (2021). Strategies to Prevent Sarcopenia in the Aging Process: Role of Protein Intake and Exercise. Nutrients, 14(1), 52. https://doi.org/10.3390/nu14010052
3. Gropper, S. S., Smith J. L. & Carr, T. P. (2018) Advanced Nutrition and Human Metabolism. (7th Ed.) Cengage Learning. p. 175-244.
4. Carbone, J. W., & Pasiakos, S. M. (2019). Dietary Protein and Muscle Mass: Translating Science to Application and Health Benefit. Nutrients, 11(5), 1136. [Link](https://doi.org/10.3390/nu11051136)
5. Cataldo, D., & Blair, M. (2015). Protein Intake For Optimal Muscle Maintenance. American College of Sports Medicine. [Link](https://www.acsm.org/docs/default-source/files-for-resource-library/protein-intake-for-optimal-muscle-maintenance.pdf)
6. Vitale, K., & Getzin, A. (2019). Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations. Nutrients, 11(6), 1289. [Link](https://doi.org/10.3390/nu11061289)
7. Morton, R. W., Murphy, K. T., McKellar, S. R., Schoenfeld, B. J., Henselmans, M., Helms, E., Aragon, A. A., Devries, M. C., Banfield, L., Krieger, J. W., & Phillips, S. M. (2018). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British journal of sports medicine, 52(6), 376–384. https://doi.org/10.1136/bjsports-2017-097608
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