- In terms of satisfying hunger, protein ranks highest of all macronutrients. In fact, subjects on high-protein hypocaloric diets often report greater satiety and overall satisfaction than those on lower-protein (higher-carbohydrate) diets (Johnston et al., 2004;Layman et al., 2003;Layman et al., 2005). It is well documented that keeping food cravings to a minimum is integral to the success of a diet.
- The calculated metabolizable energy from protein is 17 kJ/g, however the actual measured net energy yield is 13 kJ/g. The discrepancy lies in the thermogenic effect of protein ingestion, which takes into account the amount of energy needed to break-down proteins; thus, it takes more ATP to metabolize and store proteins than any other macronutrient (Westerterp-Plantenga et al., 2006). Interestingly, it has been also shown that the potent thermic increase is related to the high ATP cost of increased protein synthesis after ingesting protein (Tessari et al., 2003;van Milgen J., 2002). The metabolism of the protein source directly impacts the expenditure and it's subsequent thermic effect after ingestion (Westerterp-Plantenga et al., 2006). Thus, the absorption rate of the protein is directly related to its thermic effect on the body. Science supports this claim (Boirie et al., 1997;Dangin et al., 2001;Dangin et al., 2002), as such, hyrodrolysed whey protein and whey protein isolates (preferably CFM WPI) result in a more robust thermic effect than does whey concentrate or casein protein. (For more information on protein sources and absorption rates, see our protein source guide.
- High-protein diets result in a decrease in the ratio between fat-mass and fat-free-mass. Buchholz and Schoeller conducted a thorough meta-analysis and reported that high-protein diets resulted in approximately (or greater than) 6 lbs more weight loss after 12 weeks of treatment (Buchholz & Schoeller, 2004). Numerous well designed studies, conducted on obese populations, have shown that higher-protein diets result in a greater loss of fat-mass while maintaining lean (muscle) mass, even while in caloric deficit (Farnsworth et al., 2003;Foster et al., 2003;Johnston et al., 2004;Layman et al., 2005;Layman et al., 2003;McAuley et al., 2005).
- Those who achieve their lean physique through high-protein diets tend to maintain their fat-loss better than others. This is due to a positive shift in metabolic profile (based on healthy body composition). It has been shown that in the weight-maintenance phase of a diet, when one may observe a slight increase in body-weight, the extra pounds tend to be due to increased fat-free-mass (Westerterp-Plantenga et al., 2006).
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Buchholz AC & Schoeller DA (2004). Is a calorie a calorie? Am J Clin Nutr 79, 899S-906S.
Dangin M, Boirie Y, Garcia-Rodenas C, Gachon P, Fauquant J, Callier P, Ballevre O, & Beaufrere B (2001). The digestion rate of protein is an independent regulating factor of postprandial protein retention. Am J Physiol Endocrinol Metab 280, E340-E348.
Dangin M, Boirie Y, Guillet C, & Beaufrere B (2002). Influence of the protein digestion rate on protein turnover in young and elderly subjects. J Nutr 132, 3228S-3233S.
Farnsworth E, Luscombe ND, Noakes M, Wittert G, Argyiou E, & Clifton PM (2003). Effect of a high-protein , energy-restricted diet on body composition, glycemic control, and lipid concentrations in overweight and obese hyperinsulinemic men and women. Am J Clin Nutr 78, 31-39.
Foster GD, Wyatt HR, Hill JO, McGuckin BG, Brill C, Mohammed BS, Szapary PO, Rader DJ, Edman JS, & Klein S (2003). A randomized trial of a low-carbohydrate diet for obesity. N Engl J Med 348, 2082-2090.
Johnston CS, Tjonn SL, & Swan PD (2004). High-protein , low-fat diets are effective for weight loss and favorably alter biomarkers in healthy adults. J Nutr 134, 586-591.
Layman DK, Boileau RA, Erickson DJ, Painter JE, Shiue H, Sather C, & Christou DD (2003). A reduced ratio of dietary carbohydrate to protein improves body composition and blood lipid profiles during weight loss in adult women. J Nutr 133, 411-417.
Layman DK, Evans E, Baum JI, Seyler J, Erickson DJ, & Boileau RA (2005). Dietary protein and exercise have additive effects on body composition during weight loss in adult women. J Nutr 135, 1903-1910.
McAuley KA, Hopkins CM, Smith KJ, McLay RT, Williams SM, Taylor RW, & Mann JI (2005). Comparison of high-fat and high-protein diets with a high-carbohydrate diet in insulin-resistant obese women. Diabetologia 48, 8-16.
Tessari P, Kiwanuka E, Zanetti M, & Barazzoni R (2003). Postprandial body protein synthesis and amino acid catabolism measured with leucine and phenylalanine-tyrosine tracers. Am J Physiol Endocrinol Metab 284, E1037-E1042.
van Milgen J. (2002). Modeling biochemical aspects of energy metabolism in mammals. J Nutr 132, 3195-3202.
Westerterp-Plantenga MS, Luscombe-Marsh N, Lejeune MP, Diepvens K, Nieuwenhuizen A, Engelen MP, Deutz NE, zzout-Marniche D, Tome D, & Westerterp KR (2006). Dietary protein, metabolism, and body-weight regulation: dose-response effects. Int J Obes (Lond) 30 Suppl 3, S16-S23.