40 vs. 70g of Food Protein per Meal? No Ceiling Effect for Improvement(s) in Net Protein Balance (+65% w/ 70 vs. 40g)
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.
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 ...
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/postworkout protein anabolic response... to cut a long story short, Kim et al. are completely right to say that it is thus only...
"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...
Read my article about the previous study.
[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)
"[...] 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)|
"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 (pre-cooked/raw).
|Timing may matter albeit only for trained individuals, it seem.|
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!
- 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.
- 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.