Proteins and weight management
Protein is one of the major nutrients in our food and it is the building block of every cell in our bodies. Some of its properties are widely known: it contributes to the growth and maintenance of muscle mass, it is needed for building and repairing body tissue, and it functions as enzymes and hormones while contributing to the smooth running of the immune system1. However, proteins have another key role in nutrition; they could also be helpful in managing body weight.
Observational studies have shown that diets high in protein are associated with a lower BMI* (Body Mass Index) and waist circumference2. In addition, scientific evidence suggests that low calorie high protein diets are more effective than low calorie standard protein diets when it comes to weight loss and fat mass reduction as well as the maintenance of fat free mass2-7.
* BMI is a measure that uses your height and weight to assess if your weight is within healthy parameters
Moreover, studies have also shown that after initial weight loss, high protein diets are thought to be more likely to prevent the lost weight from returning coming back, thus making weight management easier3, 8.
Some of the possible mechanisms for explaining these effects are increased satiety and diet induced thermogenesis, and the maintenance of muscle mass that comes with high protein diets.
Several studies have demonstrated that proteins assist us in feeling fuller, preventing hunger-like symptoms for longer periods of time than carbohydrates and fats9. This is mainly due to the influence of protein consumption on appetite and satiety regulating hormones10-12.
However, the contribution of proteins to satiety is not only evident in the more intense and longer-lasting feeling of fullness that follows the consumption of a high protein meal; protein rich diets may induce satiety in the medium term as well 12,13, which may translate into reduced caloric intake. As some studies have shown, high protein diets could lead to a calorie intake reduction of up to 440 Kcal per day14.
Additionally, high protein diets have shown to have a greater effect in reducing the desire to eat late at night and reduce the craving for food than standard protein diets. This could be of value in helping to avoid overeating in the evenings and cutting down on late-night snacking15.
Increased Diet Induced Thermogenesis
When examining the properties of protein, it is also important to consider to thermic effect protein has during the digestive process. Diet Induced Thermogenesis, also known as Thermic Effect of Food, is the amount of energy needed to digest, absorb, and metabolize nutrients. It represents around 10% of the total daily energy consumption of the human body. It is influenced by the energy density and macronutrient composition of a meal. Protein generates a greater thermic effect of food than carbohydrates or fats. In fact, the thermic effect of proteins is up to ten times higher than fats, and three times higher than with carbohydrates3. This means that the body burns more calories when processing proteins than processing fats or carbohydrates.
The role of muscle mass
Muscle mass burns three times more calories per day than body fat. Each kilogram of muscle in the human body burns about 14Kcal per day, while fat only burns 4.5 Kcal per day16. Therefore, maintaining (or increasing) muscle mass, is key to boosting energy consumption throughout the day. However, anybody who embarks on a weight loss focused diet will find that one of the main challenges is to encourage loss of fat mass while maintaining lean muscle mass. Several studies have shown that, while inducing more weight and fat mass loss, high protein diets are also helpful for maintaining muscle mass6.
In addition to exercising, one of the major stimuli for muscle mass build up is the appropriate protein intake. When it comes to building muscle, not only the amount of protein consumption is important but the quality, timing and distribution of protein during the day. Several studies have shown that for better muscle stimuli, around 20 g of high quality protein should be consumed per meal, especially after an exercise bout17-21. Besides, another study have also revealed that an even distribution of protein intake during the day (e.g., 30 g/meal) is more beneficial than skewed amounts of protein intake (e.g., 10 g for breakfast, 20 g for lunch, and 60 g for dinner) in promoting building muscle mass22.
Yet and despite scientific studies the average protein intake distribution of adults is often skewed, with a low intake at breakfast, which does not reach the threshold of 20–30 g, and is typically too much at dinner time 23.
Sources of protein
The benefits of protein in managing appetite and weight are evidenced regardless of whether the protein comes from animal or plant l sources24. Recommended sources of protein are lean meats, fish, low-fat dairy, eggs, soy and other legumes, and protein rich food supplements.
- Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. 2005. Washington, DC: The National Academies Press. https://doi.org/10.17226/10490.
- Pasiakos SM, Lieberman HR, Fulgoni VL. Higher-protein diets are associated with higher HDL cholesterol and lower BMI and waist circumference in US adults. J Nutr. 2015 Mar;145(3):605-14.
- Leidy HJ, et al. The role of protein in weight loss and maintenance. Am J Clin Nutr 2015;101(Suppl):1320S–9S.
- Flechtner-Mors M, et al.Enhanced weight loss with protein-enriched meal replacements in subjects with the metabolic syndrome. Diabetes Metab Res Rev. 2010 Jul;26(5):393-405.
- Pesta DH, Samuel VT. A high-protein diet for reducing body fat: mechanisms and possible caveats. Nutr Metab (Lond). 2014 Nov 19;11(1):53.
- Wycherley TP, et al. Effects of energy-restricted high-protein, low-fat compared with standard-protein, low-fat diets: a meta-analysis of randomized controlled trialsAm J Clin Nutr 2012;96:1281–98.
- Layman, DK, et al. A Moderate-Protein Diet Produces Sustained Weight Loss and Long-Term Changes in Body Composition and Blood Lipids in Obese Adults. J Nutr. 2009 Mar;139(3):514-21.
- Aller, EE., et al. Weight loss maintenance in overweight subjects on ad libitum diets with high or low protein content and glycemic index: the DIOGENES trial 12-month results. Int J Obes (Lond). 2014 Dec;38(12):1511-7.
- Dhillon, J., et al. The Effects of Increased Protein Intake on Fullness: A Meta-Analysis and Its Limitations. J Acad Nutr Diet. 2016 Jun;116(6):968-83.
- Bowen J et al. Appetite regulatory hormone responses to various dietary proteins differ by body mass index status despite similar reductions in ad libitum energy intake. The Journal of Clinical Endocrinology & Metabolism.2006; 91(8): 2913-9.
- Belza A, Ritz C, Sørensen MQ, Holst JJ, Rehfeld JF, Astrup A. Contribution of gastroenteropancreatic appetite hormones to protein-induced satiety. Am J Clin Nutr. 2013 May;97(5):980-9.
- Yang D, Liu Z, Yang H, Jue Y. Acute effects of high-protein versus normal-protein isocaloric meals on satiety and ghrelin. Eur J Nutr. 2014 Mar;53(2):493-500.
- Westerterp-Plantenga MS, Nieuwenhuizen A, Tomé D, Soenen S, Westerterp KR. Dietary protein, weight loss, and weight maintenance. Annu Rev Nutr. 2009;29:21-41.
- Weigle DS et al. A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations. Am J Clin Nutr. 2005; 82: 41-8
- Leidy, H.J.; Tang, M.; Armstrong, C.L.; Martin, C.B.; Campbell, W.W. The effects of consuming frequent, higher protein meals on appetite and satiety during weight loss in overweight/obese men. Obesity 2011, 19,818–824.
- Butte ND and Caballero B. (2014) Energy Needs assessments and requirements. In: Ross AC, Caballero B, Cousins RJ, Tucker KL and Ziegler TR, eds. Modern Nutrition in Health and Disease, eleventh Edition. Philadelphia : Wolters Kluwer Health/Lippincott Williams & Wilkins, pp. 88-101
- Symons TB, et al. A moderate serving of high-quality protein maximally stimulates skeletal muscle protein synthesis in young and elderly subjects. J Am Diet Assoc. 2009 Sep;109(9):1582-6
- Moore DR, et al. Ingested protein dose response of muscle and albumin protein synthesis after resistance exercise in young men. Am J Clin Nutr 2009;89:161–8.
- West DWD, et al. Rapid aminoacidemia enhances myofibrillar protein synthesis and anabolic intramuscular signalling responses after resistance exercise. Am J Clin Nutr 2011;94:795–803.
- Areta JL, et al. Timing and distribution of protein ingestion during prolonged recovery from resistance exercise alters myofibrillar protein synthesis. J Physiol. 2013 May 1;591(9):2319-31.
- Witard, OC. Et al. Myofibrillar muscle protein synthesis rates subsequent to a meal in response to increasing doses of whey protein at rest and after resistance exercise. Am J Clin Nutr 2014; 99:86–95.
- Mamerow MM, et al. Dietary Protein Distribution Positively Influences 24-h Muscle Protein Synthesis in Healthy Adults. J Nutr. 2014 Jun; 144(6): 876–880.
- Paddon-Jones, D., et al. Protein and healthy aging. Am J Clin Nutr 2015;101(Suppl):1339S–45S.
- Neacsu M, Fyfe C, Horgan G, Johnstone AM. Appetite control and biomarkers of satiety with vegetarian (soy) and meat-based high-protein diets for weight loss in obese men: a randomized crossover trial. Am J Clin Nutr. 2014 Aug;100(2):548-58.