“Protein, along with fiber and water, were significantly and positively correlated with satiety scores.” – T.L. Halton, Harvard University
In addition to water and fiber (Part 1), the amount of protein in food impacts whether our brain is telling us we are hungry or full. While water and fiber help us feel satisfied by activating the stretch receptors in our digestive organs, protein satisfies us by triggering short- and long-term Satiety hormones. More protein means more “full” signals being sent to our brains’ Satiety centers via our hormones. And by eating more protein we can “full” ourselves into burning bunches of body fat 🙂
These scientific findings have been shown in numerous clinical trials:
- University of Washington Study: People ate an unlimited quantity of calories while having the percentage of protein in their diet increased from 15% to 30%. They responded by unconsciously avoiding 441 excess calories per day without feeling hungry.
- University of Sussex Study: People ate either a high-protein or a low-protein meal. The high-protein people unconsciously ate 26% less than the low-protein people at their next meal without feeling hungry.
- University of Leeds Study: People ate the exact same weight of food, but one group ate a higher percent from protein. The higher-protein group unconsciously ate at least 19% fewer calories than the lower-protein group without feeling hungry.
- Karolinska Hospital Study: People ate more or less protein for lunch. The more-protein group got full on 12% fewer calories at dinner than the less-protein group.
There is no lack of proof. Here is a summary of what researchers said in their studies:
“Protein is more satiating than carbohydrate and fat in the short term…and in the long term.” – M.S. Westerterp-Plantenga, Maastricht University
“An increase in dietary protein from 15% to 30% of energy at a constant carbohydrate intake produces a sustained decrease in…caloric intake.” – D.S. Weigle, University of Washington
“Protein appears to be the macronutrient that suppresses energy intake to a greater extent than any of the other macronutrients.” – John E. Blundell, University of Leeds
“Diets high in protein…resulted in greater weight losses than traditional low-fat diets…This effect is likely due to increased satiety caused by increased dietary protein.” – D.A. Schoeller, University of Wisconsin-Madison
In summary: More protein means more Satiety. More Satiety means we are too full for low-quality food. And less low quality food means less clogging, a lower set-point, and more burning of body fat.
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- Blundell John E., Stubbs R. James. Diet Composition and the Control of Food Intake in Humans In: Bray GA, Couchard d, James WP, eds. Handbook of Obesity. New York: Marcel Dekker, 1997: 243-272.
- Booth DA, Chase A, Campbell AT. Relative effectiveness of protein in the late stages of appetite suppression in man. Physiol Behav. 1970 Nov;5(11):1299-302.PubMed PMID: 5524514.
- Halton TL, Hu FB. The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review. J Am Coll Nutr. 2004 Oct;23(5):373-85. Review. PubMed PMID: 15466943.
- Hill AJ, Blundell JE: Macronutrients and satiety; the effects of a high protein or high carbohydrate meal on subjective motivation to eat and food preferences. Nutr Behav3 :133 –144,1986 .
- Paddon-Jones D, Westman E, Mattes RD, Wolfe RR, Astrup A, Westerterp-Plantenga M. Protein, weight management, and satiety. Am J Clin Nutr. 2008 May;87(5):1558S-1561S. Review. PubMed PMID: 18469287.
- Schoeller DA, Buchholz AC. Energetics of obesity and weight control: does diet composition matter? J Am Diet Assoc. 2005 May;105(5 Suppl 1):S24-8. Review. PubMed PMID: 15867892.
- Stubbs RJ, van Wyk MC, Johnstone AM, Harbron CG. Breakfasts high in protein, fat or carbohydrate: effect on within-day appetite and energy balance. Eur J Clin Nutr. 1996 Jul;50(7):409-17. PubMed PMID: 8862476.
- 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. PubMed PMID: 16002798.
- Westerterp-Plantenga MS. The significance of protein in food intake and body weight regulation. Curr Opin Clin Nutr Metab Care. 2003 Nov;6(6):635-8. Review. PubMed PMID: 14557793.