Saturday, May 16, 2015

When it Comes to its Satiety Effect, More Protein Doesn't Help More - Athletes Trying to Lose Weight May Fare Better if They Spread Their Intake to Several 20-30g Servings

One scoop would suffice to maximize satiety. And as far as the energy balance and the compensation effect is concerned 20g of protein is actually more effective than 40, 60, or 80 g.
Come on, if you've read my article about the insulinogenic effects of whey protein ("Whey More Insulinogenic Than White Bread: Insulin Spike is Mediated by GIP Secretion in the Gut & Effect of EAAs on the Pancreas + Why Whey is Still the Better Choice" | read more), you can hardly be surprised that the insulin spike that occurs with the ingestion of large amounts of easily digestible protein and the subsequent clearance of blood sugar in healthy individuals may impair the satiating effects of protein. So, is it really that surprising that a recent investigation into the effects of dose manipulation on the subjective sensations of appetite and food intake in a cohort of athletes did not confirm the brosciene principle "you can never eat too much protein"?
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Unless your brain has already shriveled away under the influence of all the ammonia that is produced when you neglect the classic "energy delivering" nutrients, i.e. fat and carbohydrate, and "nurture" yourself with a 80% protein diet, it should thus not surprise you that the Kristen MacKenzie-Shalders, Nuala Byrne, Gary Slater, and Neil King found that 20, 40, 60 and 80g of whey protein had the exact same (within the usual statistical margin) effect on the appetite sensation of the 10 male athletes who performed both resistance and aerobic (endurance) training (21.2 ± 2.3 years; 181.7 ± 5.7 cm and 80.8 ± 6.1 kg) the researchers from the s, Queensland University of Technology, the Bond University, and the University of the Sunshine Coast had recruited for the four counter-balanced testing sessions during which the subjects consumed a manipulated whey protein supplement (20, 40, 60 or 80 g protein) 1 hour after a standardised breakfast.
Figure 1: Effects of 20, 40, 60 and 80g post-breakfast whey protein "snack" on hunger (VAS | MacKenzie-Shalders. 2015)
From previous SuppVersity articles you will be aware of the futility of visual appetite scores (you get a line where a cross on the left would "no hunger" and on the right would be "ravenous" and the scientists simple measure where their subjects left their mark) as they were used to create Figure 1.
One piece of advice: If you want to make it easy for yourself and your clients, just stick to the SuppVersity 30g of quality protein (=high EAA, like meats, eggs, fish, dairy, pea, soy, etc.) with every meal. If you follow this simple rule, and eat 3-5 meals per day and an optional whey protein shake after workouts you come damn close to "optimal". This does not mean that a lower meal frequency and intermittent or alternate day fasting cannot be viable short-term strategies to shed body fat if you are dieting, or a sedentary couch potato (Johnstone. 2014).
Figure 2: Food intake of subsequent ad-libitum meal that was served thee hours after the protein supplement and thus 4h after standardized breakfast (MacKenzie-Shalders. 2015).
What really counts are not subjective feelings, but objectively measurable data. Data like those represented in Figure 2, data that represent the subsequent energy intake on an ad-libitum (=eat as much as you want) meal that was served three hours after the protein supplement.

Eventually, the additional data from the test meal does yet not change the original results: While the provision of extra protein 1h after the test breakfast lead to a significant decrease in ratings of hunger (50–65%; P < 0.05) at the time of supplement consumption, the scientists did not find evidence to confirm the broscientific hypothesis that more protein would trigger a more pronounced appetite suppression.

It is thus not surprising that there were no significant differences between the conditions at any time point for the energy consumed in the ad libitum meal, either: 4382 ± 1004, 4643 ± 982, 4514 ± 1112, 4177 ± 1494 kJ - that's basically the exact same intake, irrespective of the size of the protein preload.
So what do we make with the results? The authors are making a point, when they caution that "excessive, frequent protein intake may be problematic if they compromise [an athlete's] dietary energy or carbohydrate intake relative to their individual requirements" (MacKenzie-Shalders. 2015). On the other hand, the study provides a mechanistic explanation for the observation that staggering a meal containing 14% protein over a longer time frame significantly impacts on appetite hormones including glucagon-like peptide 1 (learn more) and ghrelin (more) with higher satiety sensations and lessened sensations of hunger over three hours (Lemmens, Martens, Born, Martens, & Westerterp-Plantenga, 2011).
It is thus obvious that neither the whey induced decrease in appetite ratings, nor its effects on energy intake on a subsequent meal scale (=in this case this means "increase") with the amount of whey protein you "snack", bro ;-)

Practically speaking the result is thus much similar to studies on the protein synthetic response to whey protein in young individuals. Studies, which show that the same 20g of whey protein which suffice to maximally stimulate the post-prandial protein synthesis (in young men!), will also be enough to maximize the satiety effect of whey protein. Whether this ceiling effect is in any form related to the initially cited insulinogenic effect of whey protein is yet questionable, because the latter "ceils" with ~30g, too. In view of the fact that the energy-overcompensation was maximal with the 20g dose (20g protein ~80kcal; energy reduction on subsequent meal ~120kcal+), it appears logical to assume that anyone looking to lose weight would be best off if he or she ingested more frequent 20-30g whey meals vs. one bolus ingestion of 80-120g - a result that is in line with the latest meta-analysis on the effects of meal frequency on weight loss and body composition which also suggests that there's "a potential benefit of increased feeding [and thus protein intake] frequencies for enhancing body composition" (Schoenfeld. 2015) | Comment on Facebook!
  • Johnstone, A. "Fasting for weight loss: an effective strategy or latest dieting trend&quest." International Journal of Obesity (2014).
  • Lemmens, Sofie G., et al. "Staggered meal consumption facilitates appetite control without affecting postprandial energy intake." The Journal of nutrition 141.3 (2011): 482-488.
  • MacKenzie-Shalders, Kristen, et al. "The effect of a whey protein supplement dose on satiety and food intake in resistance training athletes." Appetite (2015).
  • Schoenfeld, Brad Jon, Alan Albert Aragon, and James W. Krieger. "Effects of meal frequency on weight loss and body composition: a meta-analysis." Nutrition Reviews 73.2 (2015): 69-82.