Saturday, November 5, 2016

40 vs. 70g of Food Protein per Meal? No Ceiling Effect for Improvement(s) in Net Protein Balance (+65% w/ 70 vs. 40g)

This study does almost everything right and yet, it still needs a follow up study to address the question whether the results would be the same for fast(er) digesting proteins such as whey protein where 'more', i.e. ever-increasing boluses of protein, could actually increase the amount of protein that is being fet into gluconeogenesis, bros.
You've read it here, you've read it elsewhere: Simply doubling your protein intake ain't going to double your gains. That's true and the latest data from the Center for Translational Research in Aging and Longevity at the University of Arkansas for Medical Sciences ain't going to change that.

The questionable, if not incorrect overemphasis on postprandial (meaning right after you ingested a protein shake) and/or post-exercise and -prandial (meaning after the protein shake you consumed right after a resistance training workout) skeletal muscle protein synthesis of the vast majority of studies that investigate the effects of different doses of protein on acute protein kinetics has, however, given rise to the intrinsically flawed idea that any extra protein (in excess of 20-40g of high EAA protein, depending on the study you look at | the younger the subjects, the less appears necessary) would be wasted.
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In the experiment for their latest paper, Kim, Schutzler, Schrader, Spencer, Azhar, Ferrando and Wolfe went one step further. In a previous study in older subjects (discussed at the SuppVersity News a year ago | read it), the authors have already proven the ...
Read my article about the previous study.
"potential importance of suppression of protein breakdown in response to dietary [meaning intake from food] intake of meals containing two levels of protein totaling either 0.8 or 1.5 g protein/kg/day...

[More specifically, they] found that at both levels of dietary protein [i.e. 0.8 or 1.5 g protein/kg/day from food] whole body net protein balance became positive in the fed state compared with the fasted state, mainly due to reductions in protein breakdown" (Kim. 2015) 
This novel focus on the response to (a) food proteins and (b) the important net protein balance differentiates the study at hand, as well as the previously quoted preceding study from the rest of the pack which focused entirely on the response of muscle (often to various forms of protein supplements, instead of foods) and may thus (a) underestimate the total anabolic response to feeding and (b) give the false impression that it takes protein supplements to maximize the postprandial / pos-workout protein anabolic response... to cut a long story short, Kim et al. are completely right to say that it is thus only...
"[...] reasonable to examine whole body effects of exercise in the context of quantifying the anabolic response to different levels of dietary protein [as they did it in their latest study in which they] have quantified protein kinetics (protein synthesis (PS), breakdown (PB), and net balance (NB)) at the whole body level before and throughout the response to two levels of protein intake in mixed meals with or without prior resistance exercise in healthy young adults, [hypothesizing] that 1) the whole body net anabolic response (NB) would be greater with intake of 70 g protein, compared with 40 g protein in mixed meals; and 2) the whole body net anabolic response to either level of dietary protein in mixed meals would be greater following resistance exercise" (Kim. 2016).
To test this hypothesis, the scientists recruited twenty-three healthy subjects [18–40 yr] who didn't suffer from diabetes, or any other active malignancy within the past 6 mo, didn't have gastrointestinal bypass surgery, a chronic inflammatory disease, low hematocrit or hemoglobin concentration, low platelets, concomitant use of corticosteroids, any unstable medical conditions, and who already performed resistance exercise more than once per week.
Table 1: Subject characteristic (before the experiment | Kim. 2016)
We are thus dealing with previously trained, albeit not exactly jacked young subjects (see Table 1 for detailes subject characteristics) who may be considered representative of 'the average gymgoer' who were randomly assigned to the resistance exercise group (X) or the resting group (R).
"The resistance exercise bout consisted of 3 sets of 10 repetitions of bench press, lateralis pull-down, leg press, and leg extension each at 80% of 1 repetition maximum (1 RM, the maximum weight that can be lifted for 1 repetition). Each set was completed within 30 s. The rest interval between sets was <2 min, and the entire exercise bout was completed in ∼45–50 min" (note: the subjects trained only on day 4 | my emphasis in Kim. 2016).
To standardize the subject's dietary intake(s) the meals for both, the medium and high protein groups were provided for both, the 3-day run-in period (intended to be dietary normalization period) before the metabolic study and the metabolic study on day 4.
This is not the end of the 30g of protein per meal rule: Why's that? Well, first of all the scientists measured total body protein turnover. It is thus not possible to say how much of the 65% decrease in protein breakdown was muscle specific (some people will argue the answer is zero). In addition to that, the study at hand provides evidence only for the acute effects of a single large high protein meal. The chronic effect could be different or less pronounced - especially if this meal is consumed as part of a diet that is already high in protein.
The protein source of choice was, just as in the previously cited study in older individuals (Kim. 2015) 85% lean ground beef from a local grocery that was formed into patties weighing 113.4 g (4 oz) or 283.5 g (10 oz) of the beef (precooked/raw).
Table 2: Macronutrients of 3-day run-in on day 1–3 and metabolic infusion study on day 4; Values are expressed as means SE. Each subject consumed his or her respective interventional foods based on their sex; n number of subjects. X, exercise group; R, resting group; MP, low protein; HP, higher protein; M, male; F, female; CHO, carbohydrate (Kim. 2016)
Subjects were asked to record time of meal consumption and percentage of meal consumption and to photograph the meal before and after consumption, as well as to return all unused or empty meal/supplement packaging on the morning of the fourth day when they reported to the lab for the metabolic study (only subjects who achieved a minimum compliance of 80% consumption of meals progressed to the metabolic study).
Timing may matter albeit only for trained individuals, it seem.
Remember: For trained individuals timing may matter - While the evidence for nutrient and protein timing may be skinny (Kerksick. 2008; Aragon 2013; Schoenfeld. 2013), it's not as if there was no data suggesting that you want to put a special emphasis on consuming adequate amounts of high quality [=high essential amino acid (EAA)] protein such as whey (or dairy in general), meat, eggs, fish, soy or pea protein in the vicinity of your workouts.

Needless to say that this does not imply that you "wasted" your time whenever you fail to get your protein shake or high protein meal in within X minutes after your workout! 
By the means of phenylalanine as a tracer amino acids, the subjects' individual whole body protein kinetics were calculated based on the determinations of the rate of appearance (Ra) into the plasma of phenylalanine and tyrosine and the fractional Ra of endogenous tyrosine converted from phenylalanine as in the previous study (18). The analysis of this data yielded the following results (Kim. 2016): (a) Exercise did not significantly affect protein kinetics and blood chemistry, the feeding, however, (b) resulted in a positive net protein balance (NB) at both levels of protein intake, but...
  • Figure 1: Changes in rates of whole body protein net balance (NB), synthesis (PS), and breakdown (PB) from the fasted state in response to meal containing 40 g (MP) or 70 g (HP) of dietary protein with prior resistance exercise (X) or time-matched resting (R | Kim. 2016).
    the net protein balance (NB) was  65% greater in response to the meal containing HP vs. MP (i.e. 40g vs. 70g of protein; P < 0.00001) - irrespective of exercise, 
  • the greater NB with HP was achieved primarily through a 66% greater reduction in protein breakdown (PB) and to a lesser extent stimulation of protein synthesis (for all, P < 0.0001), and 
  • the HP resulted in greater plasma essential amino acid responses (P < 0.01) vs. MP, with no differences in insulin and glucose responses - likewise without sign. differences in the exercise (X-MP and X-HP) vs .the resting (R-MP and R-HP, respectively, in Figure 1) condition. 
As the scientists point out in the conclusion of their study, the ingestion of an increased amount of protein in form of a whole protein (in this case lean beef) will thus significantly improve the whole body net protein balance in the rested and trained state in healthy, young male and female subjects - mostly due to a previously often overlooked reduction in protein breakdown.
Bottom line: The study addresses an important question that had been left open in the previously discussed study in older subjects, i.e. 'Is the beneficial effect of increased protein intakes an age-specific phenomenon?' - with the answer being 'no, it isn't' and the study providing further evidence of the benefit of extra protein in both a sedentary and resistance training context, the study at hand provides further incentive to 'super-size" your average per meal protein intake to achieve total protein intakes way beyond the USDA recommendation of only 0.8g/kg body weight.

Latest Study Shows that a 3.3 g/kg High-Protein Diet is Safe -- And Yes, This Means it Doesn't Hurt Your Kidney or Liver | more
What the study does not do, however, is to address the question whether that's the same for fast-absorbing (more anabolic) whey protein, where both, the protein anabolic response (i.e. acute postprandial protein synthesis) as well as the postprandial protein breakdown could still show a ceiling effect in both, young and older individuals. Until this interaction with protein quality / the type of protein will not have been investigated, it still appears to make sense to aim for a higher per meal (and thus total) protein intake - after all, Antonio et al. (2016) have only recently shown that the often-cited potential detrimental effects on your health simply don't exist | Comment on Facebook!
References:
  • Antonio J, Ellerbroek A, Silver T, et al. A high protein diet has no harmful effects: a one-year crossover study in resistance-trained males. J Nutr Metab. 2016.
  • Aragon, Alan Albert, and Brad Jon Schoenfeld. "Nutrient timing revisited: is there a post-exercise anabolic window?." Journal of the international society of sports nutrition 10.1 (2013): 1.
  • Kerksick, Chad, et al. "International Society of Sports Nutrition position stand: nutrient timing." Journal of the International Society of Sports Nutrition 5.1 (2008): 1.
  • Kim, Il-Young, et al. "Quantity of dietary protein intake, but not pattern of intake, affects net protein balance primarily through differences in protein synthesis in older adults." American Journal of Physiology-Endocrinology and Metabolism 308.1 (2015): E21-E28.
  • Kim, Il-Young, et al. "The anabolic response to a meal containing different amounts of protein is not limited by the maximal stimulation of protein synthesis in healthy young adults." American Journal of Physiology-Endocrinology and Metabolism 310.1 (2016): E73-E80.
  • Schoenfeld, Brad Jon, Alan Albert Aragon, and James W. Krieger. "The effect of protein timing on muscle strength and hypertrophy: a meta-analysis." Journal of the International Society of Sports Nutrition 10.1 (2013): 1.