We use cookies and similar technologies to you the best experience on our site, to analyse site traffic, and for advertising purposes. The Locker. Fast, slow and medium proteins are becoming increasingly popular descriptions for protein powders.
During they are going to be the big talking point because more and more research talks about the digestion rate of proteins and either the positive impact on protein synthesis muscle building or ability to prevent catabolism muscle breakdown. If you want to use protein powders to their maximum effect you really need to understand what all of this means to you, so let's start with a simple explanation of each of the 3 types:.
Written by Reflex Nutrition Specialists in targeted sports nutrition since Exercise physiologist Helen Kollias notes on the Precision Nutrition website that it can take four hours or more for amino acid levels to peak in your body after drinking whey.
Digestion is not the same as absorption when it comes to whey, and your body is not able to use all of the nutrients from the foods and drinks you consume.
Kollias states that you can absorb a maximum of 8 to 10 grams of whey protein per hour, and it takes about an hour and a half for whey to become absorbed within the digestive tract.
That means if you drink a shake that has more than 15 grams of whey protein, your body might not have the opportunity to absorb and use all of that protein, and the rest could become waste products. Different brands of whey protein have different compositions, so not all of them will digest at the same rate.
The researchers speculated that the large amount of muscle mass activated from the total body RT bout necessitated a greater demand for AA that was met by a higher exogenous protein consumption.
It should be noted that findings by McNaughton et al. Given that muscular development is a function of the dynamic balance between MPS and muscle protein breakdown MPB , both of these variables must be considered in any discussion on dietary protein dosage. Kim et al. Results showed that the higher protein intake promoted a significantly greater whole-body anabolic response, which was primarily attributed to a greater attenuation of protein breakdown.
Given that participants ate large, mixed meals as whole foods containing not only protein, but carbohydrates and dietary fats as well, it is logical to speculate that this delayed digestion and absorption of AAs compared to liquid consumption of isolated protein sources.
This, in turn, would have caused a slower release of AA into circulation and hence may have contributed to dose-dependent differences in the anabolic response to protein intake. A notable limitation of the study is that measures of protein balance were taken at the whole-body level and thus not muscle-specific. It therefore can be speculated that some if not much of anti-catabolic benefits associated with higher protein intake was from tissues other than muscle, likely the gut.
Even so, protein turnover in the gut potentially provides an avenue whereby accumulated amino acids can be released into the systemic circulation to be used for MPS, conceivably enhancing anabolic potential [ 25 ]. This hypothesis remains speculative and warrants further investigation. It would be tempting to attribute these marked reductions in proteolysis to higher insulin responses considering the inclusion of a generous amount of carbohydrate in the meals consumed.
Although insulin is often considered an anabolic hormone, its primary role in muscle protein balance is related to anti-catabolic effects [ 26 ]. Given evidence that a 45 g dose of whey protein causes insulin to rise to levels sufficient to maximize net muscle protein balance [ 29 ], it would seem that the additional macronutrients consumed in the study by Kim et al.
Although the previously discussed studies offer insight into how much protein the body can utilize in a given feeding, acute anabolic responses are not necessarily associated with long-term muscular gains [ 30 ].
Wilborn et al. Similarly, a lack of between-group differences in lean mass gain was found by Fabre et al. In a day study of elderly women, Arnal et al. A follow-up study by the same lab in young women reported similar effects of pulse versus spread patterns of protein intake [ 34 ]. The combined findings of these studies indicate that muscle mass is not negatively affected by consuming the majority of daily protein as a large bolus.
However, neither study employed regimented resistance training thereby limiting generalizability to individuals involved in intense exercise programs. Insights into the effects of protein dosage can also be gleaned from studies on intermittent fasting IF.
Typical IF protocols require intake of daily nutrients, including protein, in a narrow time-frame — usually less than 8 h — followed by a prolonged fast. A recent systematic review concluded that IF has similar effects on fat-free mass compared with continuous eating protocols [ 35 ].
However, the studies reviewed in the analysis generally involved suboptimal protein intakes consumed as part of a low-energy diet without a resistance training component, again limiting the ability to extrapolate findings to resistance-trained individuals.
Helping to fill this literature gap is an 8-week trial by Tinsley et al. The TRF group lost body weight via lower energy intake kcal less on fasting vs. Perhaps most interestingly, biceps brachii and rectus femoris cross sectional area showed similar increases in both groups despite the h fasting cycles and concentrated feeding cycles in TRF, suggesting that the utilization of protein intake in the ad libitum 4-h feeding cycles was not hampered by an acute ceiling of anabolism.
Unfortunately, protein and enrgy were not equated in this study. Subsequently, an 8-week trial by Moro et al. These findings further call into question the concern for breaching a certain threshold of protein intake per meal for the goal of muscle retention.
In contrast to the above findings showing neutral-to-positive effects of a temporally concentrated meal intake, Arciero et al. During the initial day eucaloric phase, HP3 and HP6 consumed protein at 2. HP6 was the only goup that significantly gained lean mass. During the subsequent day eucaloric phase, HP3 and HP6 consumed protein at 1. HP6 maintained its lean mass gain, outperforming the other 2 treatments in this respect HP actually showed a significant loss of lean mass compared to the control.
In any case, it is notable that comparisons in this vein specifically geared toward the goal of muscle gain, hypercaloric comparisons in particular, are lacking.
An important distinction needs to be made between acute meal challenges comparing different protein amounts including serial feedings in the acute phase following resistance training and chronic meal feedings comparing different protein distributions through the day, over the course of several weeks or months.
Longitudinal studies examining body composition have not consistently corroborated the results of acute studies examining muscle protein flux. Quantifying a maximum amount of protein per meal that can be utilized for muscle anabolism has been a challenging pursuit due to the multitude of variables open for investigation. Perhaps the most comprehensive synthesis of findings in this area has been done by Morton et al.
This was based on the addition of two standard deviations to their finding that 0. In line with this hypothesis, Moore et al. Importantly, these estimates are based on the sole provision of a rapidly digesting protein source that would conceivably increase potential for oxidation of AA when consumed in larger boluses. It seems logical that a slower-acting protein source, particularly when consumed in combination with other macronutrients, would delay absorption and thus enhance the utilization of the constituent AA.
However, the practical implications of this phenomenon remain speculative and questionable [ 21 ]. The collective body of evidence indicates that total daily protein intake for the goal of maximizing resistance training-induced gains in muscle mass and strength is approximately 1.
However, 1. Bandegan et al. This reinforces the practical need to individualize dietary programming, and remain open to exceeding estimated averages. It is therefore a relatively simple and elegant solution to consume protein at a target intake of 0. Using the upper CI daily intake of 2. This tactic would apply what is currently known to maximize acute anabolic responses as well as chronic anabolic adaptations.
Further research is nevertheless needed to quantify a specific upper threshold for per-meal protein intake. Brad Schoenfeld conceived of the article. Both authors equally contributed to the writing of the manuscript. Both authors read and approved the final manuscript.
Brad Schoenfeld serves on the scientific advisory board for Dymatize Nutrition. The authors declare no other conflicts of interest.
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