In this article we deepen our knowledge of protein, its benefits in nutrition, body weight and as always, we bust myths!
Most studies show that diets that are relatively high in protein are more conducive to weight loss and subsequent weight maintenance, when it comes to free energy intake conditions, rather than diet conditions that provide the same calories.
These diets contain a sufficient absolute amount of protein (usually around 20-30% of total energy) and involve the required intake of normal protein in grams, while energy intake is reduced.
Most of the studies on protein intake in relation to weight management show improved body composition (i.e. increased lean/body fat mass ratio) that can lead to an improved metabolic profile with a relatively high protein diet.
The impact of macronutrient composition on energy homeostasis, and therefore on weight control, depends on the sum of their effects energy intake, energy expenditure and their balance.
Several mechanisms have been proposed for the effect of high-protein diets on weight loss.
The increase of thermogenesis induced by diet (TEF / Thermic Effect of Food or DIT / Diet-Induced Thermogenesis) is one of the mechanisms that are very often mentioned in the literature.
Studies with meals providing equal calories have clearly shown the thermogenic advantage of dietary protein, with caloric effects for individual nutrients being 0-3% for fat, 5-10% for carbohydrate and 20-30% for protein.
The increase in energy expenditure caused by food (i.e. dietary thermogenesis) consists of two parts: a mandatory part required for the digestion, transport and (mainly) storage of nutrients and an optional part for heat production.
As a result, all this implies that for every 1000 kcal consumed as protein, about 200-300 kcal are consumed during the process of digestion, transport and storage, compared to 50-100 kcal for carbohydrates and 0-30 kcal for dietary fat.
One of the main reasons for this is that theoretically, the biochemical efficiency of the protein is about 84%, which is low. In practice, studies in animals, infants and children have shown that the requirements for its deposition are usually even higher. A value often used is 2.38kJ per kJ of energy deposited (1.38kJ extra energy is required to deposit 1kJ of protein value), which translates to 55.3 MJ/kg, assuming the energy value of protein is 23.5 kJ/g.
This means that to create lean mass, theoretically, an additional energy feeding of 32.43 MJ per kg of protein deposited is required (55.3 MJ/kg, which is the total cost of protein deposition minus 23.5 MJ, which is the energy value of the protein).
But here things take a bad turn. You see, the efficiency of converting ingested protein into lean body mass is reduced when protein is ingested in sufficient quantities or more (about 1.3g/kg of weight per day). That said, this reduction can be significantly suppressed by weight training, suggesting that this may help maintain or improve the efficiency of protein anabolism.
Similarly, the rate at which the protein is broken down, Grow in response to familiarity with high-protein dietswhich means higher losses between meals caused by increased rates of proteolysis. Having said that, there are data suggesting that this effect can be mitigated by supplementation with essential amino acids, as offer greater suppression of protein degradation.
Of the protein consumed, only ~55% is released into the circulation and only ~55% ~10% is used for protein synthesis for skeletal muscles. This 10% is about the 27% of total protein synthesis that of the 55%.
In addition to diet-related factors, physiological factors have also been shown to influence the incorporation of amino acids into muscle tissue.
Η exercise before a meal has been shown to lead to greater de novo muscle protein synthesis. Η aerobic exercise at high intensity and the weight training increase de novo muscle protein synthesis for 24-48 hours.
On the other hand, short-term muscle inactivity results in the reduction of de novo muscle protein synthesis.
So I guess we're beginning to understand that building muscle is not easy and the effects of protein on body composition are not a simple matter of making predictions.
And it gets worse, as theoretically, the biochemical efficiency of fat is 98%, with studies typically estimating that the requirements for its deposition are more than half those for protein, with a commonly used value being 1.17kJ per kJ of energy deposited (0.17kJ extra energy is required to deposit 1kJ of fat), meaning that it will always be easier to convert dietary fat into body fat than protein deposition. This translates to 45.513 MJ/kg, assuming a fat value of 38.9 kJ/g.
This means that fat production, in theory, requires an additional energy consumption of 6.613 MJ per kg of fat (45.513 MJ/kg, which is the total cost of fat deposition minus 38.9MJ, which is the energy value of the fat).
In other words, this additional energy consumption of 32.43 MJ is mostly for fat storage and will not result in as much muscle mass gain, as 1 kg of weight gain requires about as much extra energy for the average person.
In summary, it would make sense that a very low absolute protein intake would contribute to the risk of weight regain, an "absolutely required" amount of protein would be sufficient for weight loss, body fat loss and weight maintenance, but increased protein in the diet would be necessary to improve lean body mass and resting energy expenditure.
It therefore appears that there are observations on protein intake and energy efficiency under certain conditions that can support the "Case of Stock".
This states that under overconsumption conditions, a diet that is either high or low in protein is less "metabolically efficient" than a diet that provides an average protein intake.
However, subsequent studies have failed to replicate this theoretical "metabolic inefficiency" of high-protein diets.
This has also led many researchers to formulate the hypothesis of "protein leverage" for obesity, or "protein leverage hypothesis".
This theory suggests that the body seeks to consume a certain level of dietary protein and that a reduction in dietary protein will lead to compensatory increases in total energy intake resulting in obesity.
However, protein consumption did not decrease significantly during the increase in obesity in the US.
In addition, not only a number of studies, both short and long-term, such as this, this and this in humans, or this and this in animals failed to replicate this effect, but diets higher in protein content should also demonstrate higher levels of adherence to them, as well as outperforming other diets in terms of weight regain, while not achieving neither one, nor the other.
So how do all these things come together?
As we saw in "FUNDAMENTALS OF DIET PART III - a successful diet needs realism", losses of muscle mass can predict weight gain. Let's add more data:
So here, the group that lost the most muscle also had the most adherence to this diet? Isn't that contrary to what we've seen so far?
Not if we look at what happened in protein intake between the groups:
So, the groups that increased or maintained their protein intake also had the highest adherence to the diet and we can actually say that this is reflected in the studies showing that lean mass maintenance is crucial for maintaining weight loss. It's the relatively higher protein intake compared to the other groups.
In addition, the increase in lean mass can lead to increased hunger and weight gain, since the lean body mass is a determining factor as regards on appetite and energy intake, which is true from our infancy.
This is underlined by the phenomenon that under iso-energy conditions no statistically significant difference has been shown between weight loss in high energy diets and weight loss in low energy diets. proteins or carbohydrates.
The explanation for all this is that satiety, the feeling of fullness that comes with a meal, is a key factor in the implementation of a high-protein diet.
This can be demonstrated by the fact that although the greater thermogenic effect of high-protein diets appears to be insufficient to cause greater weight loss than low-protein diets when comparisons are made with constant energy intake, under free feeding conditions participants eat less when given high-protein diets.
Or else, just because the Stock and Protein Leverage hypotheses are not true, this does not invalidate the fact that protein contributes to satiety with a meal. In fact, it should probably be the basis of your diet.
In summary, as far as fat loss is concerned, protein's unique role in satiety is what sets it apart from other macronutrients, while the benefits to lean mass come in second and sweatiest place, with dietary thermogenesis being last on the list.
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- Magkos F. The role of dietary protein in obesity. rev Endocr Metab Disord. 2020 Sep;21(3):329-340. doi: 10.1007/s11154-020-09576-3. PMID: 32740867.
- Roberts SB, Das SK. one strike against low-carbohydrate diets. cell Metab. 2015 Sep 1;22(3):357-8. doi: 10.1016/j.cmet.2015.07.022. epub 2015 Aug 13. PMID: 26278053.
- Ho KKY. diet-induced thermogenesis: fake friend or foe? J Endocrinol. 2018 Sep;238(3):R185-R191. doi: 10.1530/JOE-18-0240. epub 2018 Jun 12. PMID: 29895717.
- Tappy L. Thermal effect of food and sympathetic nervous system activity in humans. reprod Nutr Dev. 1996;36(4):391-7. doi: 10.1051/rnd:19960405. PMID: 8878356.
- Westerterp-Plantenga MS, Lemmens SG, Westerterp KR. dietary protein - its role in satiety, energetics, weight loss and health. Br J Nutr. 2012 Aug;108 Suppl 2:S105-12. doi: 10.1017/S000711114512002589. PMID: 23107521.
- 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. doi: 10.1146/annurev-nutr-080508-141056. PMID: 19400750.
- Hall KD. mathematical modelling of energy expenditure during tissue deposition. br J Nutr. 2010 Jul;104(1):4-7. doi: 10.1017/S0007117114510000206. epub 2010 Feb 5. PMID: 20132585.
- Tagawa R, Watanabe D, Ito K, Ueda K, Nakayama K, Sanbongi C, Miyachi M. Dose-response relationship between protein intake and muscle mass increase: a systematic review and meta-analysis of randomized controlled trials. Nutr Rev. 2020 Nov 4;79(1):66-75. doi: 10.1093/nutrit/nuaa104. epub ahead of print. PMID: 33300582; PMCID: PMC7727026.
- Pannemans DL, Halliday D, Westerterp KR, Kester AD. Effect of variable protein intake on whole-body protein turnover in young men and women. Am J Clin Nutr. 1995 Jan;61(1):69-74. doi: 10.1093/ajcn/61.1.69. PMID: 7825541.
- Pannemans DL, Halliday D, Westerterp KR. Whole-body protein turnover in elderly men and women: responses to two protein intakes. Am J Clin Nutr. 1995 Jan;61(1):33-8. doi: 10.1093/ajcn/61.1.33. PMID: 7825534.
- Højfeldt G, Bülow J, Agergaard J, Asmar A, Schjerling P, Simonsen L, Bülow J, van Hall G, Holm L. Impact of habituated dietary protein intake on fasting and postprandial whole-body protein turnover and splanchnic amino acid metabolism in elderly men: a randomized, controlled, crossover trial. Am J Clin Nutr. 2020 Dec 10;112(6):1468-1484. doi: 10.1093/ajcn/nqaa201. PMID: 32710741.
- Pacy PJ, Price GM, Halliday D, Quevedo MR, Millward DJ. nitrogen homeostasis in man: the diurnal responses of protein synthesis and degradation and amino acid oxidation to diets with increasing protein intakes. clin Sci (Lond). 1994 Jan;86(1):103-16. doi: 10.1042/cs0860103. PMID: 8306544.
- Quevedo MR, Price GM, Halliday D, Pacy PJ, Millward DJ. nitrogen homoeostasis in man: diurnal changes in nitrogen excretion, leucine oxidation and whole body leucine kinetics during a reduction from a high to a moderate protein intake. clin Sci (Lond). 1994 Feb;86(2):185-93. doi: 10.1042/cs0860185. PMID: 8143429.
- Gwin JA, Church DD, Hatch-McChesney A, Howard EE, Carrigan CT, Murphy NE, Wilson MA, Margolis LM, Carbone JW, Wolfe RR, Ferrando AA, Pasiakos SM. Effects of high versus standard essential amino acid intakes on whole-body protein turnover and mixed muscle protein synthesis during energy deficit: a randomized, crossover study. Clin Nutr. 2021 Mar;40(3):767-777. doi: 10.1016/j.clnu.2020..07.019. epub 2020 Jul 22. PMID: 32768315.
- Park S, Church DD, Schutzler SE, Azhar G, Kim IY, Ferrando AA, Wolfe RR. Metabolic Evaluation of the Dietary Guidelines' Ounce Equivalents of Protein Food Sources in Young Adults: a Randomized Controlled Trial. J Nutr. 2021 Mar 9:nxaa401. doi: 10.1093/jn/nxaa401. epub ahead of print. pmid: 33693735.
- Coker MS, Schutzler SE, Park S, Williams RH, Ferrando AA, Deutz NEP, Wolfe RR, Coker RH. Equivalent servings of free-range reindeer promote greater net protein balance compared to commercial beef. Int J Circumpolar Health. 2021 Dec;80(1):1897222. doi: 10.1080/22423982.2021.1897222. PMID: 33704030; PMCID: PMC7954490.
- Groen BB, Horstman AM, Hamer HM, de Haan M, van Kranenburg J, Bierau J, Poeze M, Wodzig WK, Rasmussen BB, van Loon LJ. Post-Prandial Protein Handling: You Are What You Just Ate. PLoS One. 2015 Nov 10;10(11):e0141582. doi: 10.1371/journal.pone.0141582. PMID: 26556791; PMCID: PMC4640549.
- Nair KS, Halliday D, Griggs RC. leucine incorporation into mixed skeletal muscle protein in humans. Am J Physiol. 1988 Feb;254(2 Pt 1):E208-13. doi: 10.1152/ajpendo.1988.254.2.E208. PMID: 3279803.
- Trommelen J, van Loon LJC. assessing the whole-body protein synthetic response to feeding in vivo in human subjects. proc Nutr Soc. 2021 Jan 5:1-9. doi: 10.1017/S0029665120008009. epub ahead of print. pmid: 33399528.
- Trommelen J, Holwerda AM, Pinckaers PJM, van Loon LJC. Comprehensive assessment of post-prandial protein handling by the application of intrinsically labelled protein in vivo in human subjects. Proc Nutr Soc. 2021 Jan 25:1-9. doi: 10.1017/S0029665120008034. doi: 10.1017/S0029665120008034. Epub ahead of print.PMID: 33487181.
- Pennings B, Koopman R, Beelen M, Senden JM, Saris WH, van Loon LJ. Exercising before protein intake allows for greater use of dietary protein-derived amino acids for de novo muscle protein synthesis in both young and elderly men. Am J Clin Nutr. 2011 Feb;93(2):322-31. doi: 10.3945/ajcn.2010.29649. epub 2010 Nov 17. PMID: 21084649.
- Wall BT, Burd NA, Franssen R, Gorissen SH, Snijders T, Senden JM, Gijsen AP, van Loon LJ. Presleep protein ingestion does not compromise the muscle protein synthetic response to protein ingested the following morning. Am J Physiol Endocrinol Metab. 2016 Dec 1;311(6):E964-E973. doi: 10.1152/ajpendo.00325.2016. epub 2016 Oct 25. PMID: 27780822.
- Di Donato DM, West DW, Churchward-Venne TA, Breen L, Baker SK, Phillips SM. Influence of aerobic exercise intensity on myofibrillar and mitochondrial protein synthesis in young men during early and late postexercise recovery.Am J Physiol Endocrinol Metab. 2014 May 1;306(9):E1025-32. doi: 10.1152/ajpendo.00487.2013. epub 2014 Mar 4. PMID: 24595306; PMCID: PMC4010655.
- Phillips SM, Tipton KD, Aarsland A, Wolf SE, Wolfe RR. mixed muscle protein synthesis and breakdown after resistance exercise in humans. Am J Physiol. 1997 Jul;273(1 Pt 1):E99-107. doi: 10.1152/ajpendo.1997.273.1.E99. PMID: 9252485.
- Fuchs CJ, Kouw IWK, Churchward-Venne TA, Smeets JSJ, Senden JM, Lichtenbelt WDVM, Verdijk LB, van Loon LJC. postexercise cooling impairs muscle protein synthesis rates in recreational athletes. J Physiol. 2020 Feb;598(4):755-772. doi: 10.1113/JP278996. epub 2019 Dec 29. PMID: 31788800; PMCID: PMC7028023.
- Wall BT, Dirks ML, Snijders T, van Dijk JW, Fritsch M, Verdijk LB, van Loon LJ. Short-term muscle disuse lowers myofibrillar protein synthesis rates and induces anabolic resistance to protein ingestion. Am J Physiol Endocrinol Metab. 2016 Jan 15;310(2):E137-47. doi: 10.1152/ajpendo.00227.2015. epub 2015 Nov 17. PMID: 26578714.
- Weigle DS, Breen PA, Matthys CC, Callahan HS, Meeuws KE, Burden VR, Purnell JQ. 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 Jul;82(1):41-8. doi: 10.1093/ajcn.82.1.41. PMID: 16002798.
- Westerterp-Plantenga, M., Luscombe-Marsh, N., Lejeune, M. et al. Dietary protein, metabolism, and body-weight regulation: dose-response effects. Int J Obes 30, S16-S23 (2006). doi: 10.1038/sj.ijo.0803487. doi: 10.1038/sj.ijo.0803487.
- Stock MJ. gluttony and thermogenesis revisited. int J Obes Relat Metab Disord. 1999 Nov;23(11):1105-17. doi: 10.1038/sj.ijo.0801108. PMID: 10578199.
- Simpson SJ, Raubenheimer D. Obesity: the protein leverage hypothesis. obes Rev. 2005 May;6(2):133-42. doi: 10.1111/j.1467-789X.2005.00178.x. PMID: 15836464.
- Bray GA, Smith SR, de Jonge L, Xie H, Rood J, Martin CK, Most M, Brock C, Mancuso S, Redman LM. Effect of dietary protein content on weight gain, energy expenditure, and body composition during overeating: a randomized controlled trial. JAMA. 2012 Jan 4;307(1):47-55. doi: 10.1001/jama.2011Erratum in: JAMA. 2012 Mar 14;307(10):1028. PMID: 22215165; PMCID: PMC3777747.
- Hall KD. Did the Food Environment Cause the Obesity Epidemic? Obesity (Silver Spring). 2018 Jan;26(1):11-13. doi: 10.1002/oby.22073. PMID: 29265772; PMCID: PMC5769871.
- Martens EA, Lemmens SG, Westerterp-Plantenga MS. protein leverage affects energy intake of high-protein diets in humans. Am J Clin Nutr. 2013 Jan;97(1):86-93. doi: 10.3945/ajcn.112.046540. epub 2012 Dec 5. PMID: 23221572.
- Martens EA, Tan SY, Dunlop MV, Mattes RD, Mattes RD, Westerterp-Plantenga MS. protein leverage effects of beef protein on energy intake in humans. Am J Clin Nutr. 2014 Jun;99(6):1397-406. doi: 10.3945/ajcn.113.078774. doi: 10.3945/ajcn.113.078774. Epub 2014 Apr 23. PMID: 24760974.
- Hall KD, Guo J, Courville AB, Boring J, Brychta R, Chen KY, Darcey V, Forde CG, Gharib AM, Gallagher I, Howard R, Joseph PV, Milley L, Ouwerkerk R, Raisinger K, Rozga I, Schick A, Stagliano M, Torres S, Walter M, Walter P, Yang S, Chung ST. Effect of a plant-based, low-fat diet versus an animal-based, ketogenic diet on ad libitum energy intake. Nat Med. 2021 Jan 21. doi: 10.1038/s41591-020-01209-1. Epub ahead of print. PMID: 33479499.
- Hu S, Wang L, Yang D, Li L, Togo J, Wu Y, Liu Q, Li B, Li M, Wang G, Zhang X, Niu C, Li J, Xu Y, Couper E, Whittington-Davies A, Mazidi M, Luo L, Wang S, Douglas A, Speakman JR. Dietary Fat, but Not Protein or Carbohydrate, Regulates Energy Intake and Causes Adiposity in Mice. cell Metab. 2018 Sep 4;28(3):415-431.e4. doi: 10.1016/j.cmet.2018.06.010. epub 2018 Jul 12. PMID: 30017356.
- Wu Y, Li B, Li L, Mitchell SE, Mitchell SE, Green CL, D'Agostino G, Wang G, Wang L, Li M, Li J, Niu C, Jin Z, Wang A, Zheng Y, Douglas A, Speakman JR. Very-low-protein diets lead to reduced food intake and weight loss, linked to inhibition of hypothalamic mTOR signaling, in mice. Cell Metab. epub 2021 Mar 04.
- Larsen TM, Dalskov SM, van Baak M, Jebb SA, Papadaki A, Pfeiffer AF, Martinez JA, Handjieva-Darlenska T, Kunešová M, Pihlsgård M, Stender S, Holst C, Saris WH, Astrup A; Diet, Obesity, and Genes (Diogenes) Project. Diets with high or low protein content and glycemic index for weight-loss maintenance. N Engl J Med. 2010 Nov 25;363(22):2102-13. doi: 10.1056/NEJMoa1007137. PMID: 21105792; PMCID: PMC3359496.
- Johnson KO, Holliday A, Mistry N, Cunniffe A, Howard K, Stanger N, O'Mahoney LL, Matu J, Ispoglou T. An Increase in Fat-Free Mass is Associated with Higher Appetite and Energy Intake in Older Adults: a Randomised Control Trial. Nutrients. 2021 Jan 1;13(1):141. doi: 10.3390/nu13010141. PMID: 33401473; PMCID: PMC7824356.
- Blundell JE, Caudwell P, Gibbons C, Hopkins M, Naslund E, King N, Finlayson G. Role of resting metabolic rate and energy expenditure in hunger and appetite control: a new formulation. dis Model Mech. 2012 Sep;5(5):608-13. doi: 10.1242/dmm.009837. PMID: 22915022; PMCID: PMC3424457.
- King JA, Wasse LK, Ewens J, Crystallis K, Emmanuel J, Batterham RL, Stensel DJ. Differential acylated ghrelin, peptide YY3-36, appetite, and food intake responses to equivalent energy deficits created by exercise and food restriction. J Clin Endocrinol Metab. 2011 Apr;96(4):1114-21. doi: 10.1210/jc.2010-2735. epub 2011 Jan 26. PMID: 21270331.
- Wells JC, Davies PS, Hopkins M, Blundell JE. The "drive to eat" hypothesis: energy expenditure and fat-free mass but not adiposity are associated with milk intake and energy intake in 12-week infants. Am J Clin Nutr. 2021 Apr 13:nqab067. doi: 10.1093/ajcn/nqab067. epub ahead of print. PMID: 33851194.
- Aronica L, Rigdon J, Offringa LC, Stefanick ML, Gardner CD. Examining differences between overweight women and men in 12-month weight loss study comparing healthy low-carbohydrate vs. low-fat diets. Int J Obes (Lond). 2021 Jan;45(1):225-234. doi: 10.1038/s41366-020-00708-y. Epub 2020 Nov 14. PMID: 33188301; PMCID: PMC7752762.
- Whitehead JM, McNeill G, Smith JS. The effect of protein intake on 24-h energy expenditure during energy restriction. Int J Obes Relat Metab Disord. 1996 Aug;20(8):727-32. PMID: 8856395.