In Part 1 of this article, Expert Matthew Smith discussed how, despite it’s bad reputation, protein can actually aid in weight loss. In this part he presents three more reasons why you should get more protein in your diet…

4. Protein provides satiety

Clifton & Keogh (2007) state that Protein is more satiating than carbohydrates or fat [6] which is why high protein diets are most commonly used for fat loss. Satiety is another word for feeling full after a meal, so having a high protein meal would leave you feeling full for longer than a high fat or high carbohydrate meal.


As Paddon-Jones et al (2008) stated protein “may facilitate a reduction in energy consumption” [7] meaning that because protein increases satiety, it may lead to people consuming less calories during the day.

This has been taken to extremes by certain fad diets and meal replacement shake companies but, used sensibly, increasing your protein can help you lower your calories without feeling overly hungry.

5. Protein will improve immune function

A study by Daly et al (1990) stated that “protein calorie malnutrition impairs host immunity … resulting in increased opportunistic infection” [8]. This was based on patients in hospital so the statement may not apply quite as much to those of us who are currently fit and healthy, but it does demonstrate how increasing protein can improve immune function.

why protein to lose weight_2Those of you who train regularly, or perhaps verging on overtraining can have your immune function impaired [9], especially if you are already suffering from stress, or persistent fatigue.

Having a high protein diet can help prevent your immune system being negatively affected, though if you are worried about the effects of overtraining I would suggest looking into your current training program first.

6. Dietary protein will increase muscle protein synthesis

As I wrote in my Pre-workout meals article, and as stated in the following studies [10][11][12] dietary protein will increase muscle protein synthesis.

Without going into too much detail, muscle protein synthesis is the removal and repair of damaged proteins followed by replacement of brand new proteins. During a workout your muscles will suffer micro-trauma, they are then repaired and replaced leaving the muscle stronger and bigger (after long periods of training obviously).

If you are not consuming adequate protein, your muscles will not be able to get bigger or stronger which is why it is almost impossible for people to get bigger muscles when restricting calories. Leucine in particular has been shown to “stimulate recovery of skeletal muscle protein synthesis after exercise” in rats [13].

Having more muscle mass can increase energy expenditure, or as Wolfe (2006) put it “even relatively small differences (e.g. 10kg) in muscle mass could have a significant effect on energy balance” stating that 10kg of muscle mass could translate to 100kcal per day in expended energy [14].

Connect with Expert Matthew Smith.


[1] Berardi, J., Andrews, R. 2013. The Essentials of Sport and Exercise Nutrition 2nd ed. Precision Nutrition, Inc. pp 162-165
[2] Pasiakos, S., Cao, J., Margolis, L., Sauter, E., Whigham, L., McClung, J., Rood, J., Carbone, J., Combs Jr., G., Young, A. 2013. Effects of high-protein diets on fat-free mass and muscle protein synthesis following weight loss: A randomised controlled trial. The FASEB Journal 27(9): 3837-3847
[3] Layman, D., Boileau, R, Erickson, D., Painter, J., Shiue, H., Sather, C., Christou, D. 2003. A reduced ratio of carbohydrate to protein improves body composition and blood lipid profiles during weight loss in adult women. Journal of Nutrition 133(2): 411-7
[4] Halton, T., Hu, F. 2004. The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review. Journal of the American College of Nutrition 23(5): 373-85
[5] Johnston, C., Day, C., and Swan P. 2002. Postprandial thermogenesis is increased 100% on a high-protein, low-fat diet versus a high-carbohydrate, low-fat diet in healthy young women. Journal of the American College of Nutrition 21(1): 55-61
[6] Clifton, P., Keogh, J. 2007. Metabolic effects of high protein diets. Current Atherosclerosis Reports 9(6): 472-8
[7] Paddon-Jones, D., Westman, E., Mattes, R., Wolfe, R., Astrup, A., Westerterp-Plantenga, M. 2008. Protein, weight management, and satiety. American Society for Clinical Nutrition 87(5): 1558S-1561S
[8] Daly, J., Reynolds, J., Sigal, R., Shou, J., Liberman, M. 1990. Effect of dietary protein and amino acids on immune function. Critical Care Medicine 18(2): S86- 93
[9] MacKinnon, L. 2000. Overtraining effects on immunity and performance in athletes. Immunology and Cell Biology 78: 502-509
[10] Greenhaff, P., Karagounis, N., Pierce, N., Simpson, E., Hazell, M., Layfield, H., Wackerhage, K., Smith, P., Atherton, A., Selby, M., Rennie, M. (2008) Disassociation between the effects of amino acids and insulin on signalling, ubiquitin ligases, and protein turnover in human muscle. American Journal of Physiology – Endocrinology and Metabolism 295(3): 595-604
[11] Boirie, Y., Dangin, M., Gachon, P., Vasson, M., Maubois, J., Beaufrere, B. (1997) Slow and fast dietary proteins differently moderate postprandial protein accretion. Proceedings of the National Academy of Sciences of the United States of America 94(26): 14930-14935
[12] Tang, J., Moore, D., Kujbida, G., Tarnopolsky, M., Phillips, S. (2009) Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. Journal of Applied Physiology 107(3): 987-992
[13] Anthony, J., Anthony, T., Layman, D. 1999. Leucine Supplementation Enhances Skeletal Muscle Recovery in Rats Following Exercise. The Journal of Nutrition 129(6): 1102-1106
[14] Wolfe, R. 2006. The underappreciated role of muscle in health and disease. The American Journal of Clinical Nutrition 84(3): 475-482

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