Bustin Broscience - a new article series by the Appnuts
- 11-28-2008, 12:56 PM
Bustin Broscience - a new article series by the Appnuts
where rep points don't matter
The appnuts got together and dedcided we wanted to give some back to the community, and so we're starting a new regular feature called Bustin Broscience. We're going to take bits of common broscience and examine them, try to find scientific justifications to either support or contradict them. We'll present it to you in a clean easy to read format, giving you more tools to work with. I expect we'll all learn a few things we didn't know (or get scientific evidence for things we felt were true) over the course of this series of articles. Our first topic is "You can only absorb 25 grams of protein in one meal" by EasyEJL, Applied Nutriceuticals Rep.Animis Rep
- 11-28-2008, 12:56 PM
How much protein per meal?
Its something I’m sure you’ve all heard before although the exact number used varies. “You can only absorb ___ grams of protein in one meal,” with 25g being probably the most commonly used number. Like with many pieces of broscience, the real answer is a lot more complex. Lets start with the simplest part of this, ignoring bodybuilding entirely. For men, the USRDA for protein is .8g/kg. That equates to 72g of protein for a 200lb male. Divided into 3 meals, that would only come to 24g per meal, which falls inside the 25g per meal myth. But that of course is the minimum recommended, not a maximum absorbable.
From what I’ve seen, I believe the myth started with some of the early studies on egg protein absorption. For whatever reason, 25g is the commonly used amount for egg protein studies, which is the amount roughly in 3 jumbo eggs, or 4 large eggs. There are numerous studies done with the egg protein showing various amounts escaping digestion. A fair example is this one Amount and fate of egg protein escaping assimilation in the small intestine of humans -- Evenepoel et al. 277 (5): 935 -- AJP - Gastrointestinal and Liver Physiology . The important piece to keep in mind is that even in this case the protein absorption throughout the digestive tract occurs over a 72 hour period given the time it takes to pass through the intestines, with a total recovery of approx 5% of the protein leaving the body rather than being used. But even with egg’s high bioavailability and rapid absorption, you don’t see peak levels until 3 hours or so post intake.
With other protein forms such as milk based (casein, whey, etc), you have both different digestion rates, as well as different absorption rates. This study Compared with casein or total milk protein, digestion of milk soluble proteins is too rapid to sustain the anabolic postprandial amino acid requirement -- Lacroix et al. 84 (5): 1070 -- American Journal of Clinical Nutrition specifically was looking at milk based proteins. What is interesting for the sake of this myth is the figure 3 graph of changes to serum amino acids. The milk soluble protein isolate reached a peak serum BCAA level 3x higher than either casein or total milk protein within 1 hour and remained 2x as high through the second hour. It dropped back to below the level of the other proteins by 4 hours. This was based on approx 22g of protein in each of the types. The important point demonstrated is that amino acid levels are able to be elevated significantly higher than what 22g of casein will raise it in a single meal. Note that the total milk protein and casein both showed elevated BCAA levels out to 8 hours, and overall elevated amino acid levels to 7 hours, showing how long a single meal can take to travel through digestion.
A similar study The digestion rate of protein is an independent regulating factor of postprandial protein retention -- Dangin et al. 280 (2): E340 -- AJP - Endocrinology and Metabolism was done using free amino acids, whey, casein and repeated whey meals. These were done with 30g. Even with the free form amino acids, peak plasma concentration of (remember, this is basically eating a spoonful of leucine) wasn’t until 60 minutes.
A compilation of protein studies is available as a separate study here http://www.humankinetics.com/eJourna.../pdfs/5642.pdf which gives some pretty specific numbers for protein absorption rates. Using caseins they show an approximate rate of 6g/hr, with whey at the top being 8-10g/hr. Using those as maximums per day, you can probably reach (in 3 meals) as much as 50g of casein, and still utilize it all. Whey on the other hand dose show the fast spike but relatively fast drop as well, so although there is a theoretical higher grams per hour its washout is also higher, requiring more frequent meals to maintain the absorption, so probably 25-30g as whey every 3 hours gets you optimal absorption.
So what does this all mean? Well, for starters its pretty obvious that with casein supplying aminos for as much as 9 hours post-meal and a max absorption in normal healthy individuals NOT weight training of around 6 grams per hour means that a meal as large as 54g of casein can be almost entirely absorbed. As far as fish, poultry or beef goes, there aren’t nearly as many studies done, and none that are so granular in terms of timing. Given that eggs have around a 3g/hr rate, and /soy go from 3-4g/hr that it is not at all unreasonable to assume that animal sources have somewhere in the range of 3-10g/hr.
The piece missing from any studies I could find which could make a significant difference is the addition of carbohydrates and/or fats. Is it possible that with the addition of fats or fiber that a larger amount of whey proteins can be taken in a meal, with overall movement of the protein from stomach to amino acids in bloodstream would be slowed down enough that the 10g per hour could be maintained for 5 or 6 hours keeping the 10g/hr bloodstream absorption? I think it is likely to be the case, and hope that someday we see some studies done with more real world scenarios than fasted whey only meals.
So is the myth busted? You bet, its definitely possible to take in as much as 50-60g of casein in a single serving, and use the vast majority of it, and that is for a non-weight training individual. With increased protein turnover in a bodybuilder, its likely that you can absorb even more. The other thing I learned as I researched this that may interest many of the rest of you is as below
“An important question then must be posed: “Does a more rapidly absorbable protein result in greater in vivo protein synthesis?” This is a central issue of large protein consumption with fitness enthusiasts, athletes, and bodybuilders. Early findings suggest that rapidly absorbed proteins such as free amino acids and WP, transiently and moderately inhibit protein breakdown, yet stimulate protein synthesis by 68% [using nonoxidative leucine disposal (NOLD) as an index of protein synthesis]. Casein protein has been shown to inhibit protein breakdown by 30% for a 7-h postprandial period, and only slightly increase protein synthesis. Rapidly absorbed amino acids despite stimulating greater protein synthesis, also stimulate greater amino acid oxidation, and hence results in a lower net protein gain, than slowly absorbed protein. Leucine balance, a measurable endpoint for protein balance, is indicated in Figure 1, which shows slowly absorbed amino acids (~ 6 to 7 g/h), such as CAS and 2.3 g of WP repeatedly taken orally every 20 min (RPT-WP), provide significantly better protein balance than rapidly absorbed amino acids.”
A quickie summary of this is that although casein seems to only slightly increase protein synthesis, overall there is a better net protein gain than with faster absorbed proteins sich as whey, unless you feel like taking 3g of whey every 20 minutes. So I may be changing a bit more of what little I take in protein shakes now for more casein, or a mixed casein/whey source.
Broscience Busted - There is no particular evidence that 25, 30, 40 or even 50g is a maximum absorbable in a single meal, the type of protein has a lot more bearing. As much as 60 or 70g protein from casein could be taken in and still be used over the next 8 hours even in a non-weightlifting individual.Animis Rep
- 11-28-2008, 12:59 PM
Hope you enjoy that first article, there will be more in the series coming regularly in the future. Any comments, questions or suggestions feel free to let us know. It was interesting for me to research this, as i'm still a bit surprised as to how long even BCAAs or whey take to get to bloodstream (for all that people say they are fast), and how relatively rapidly casein gets there.Animis Rep
One recommendation, though. I think it would be beneficial to impatient readers if you were to put a 'cliff notes' in bold at the bottom. Just a one or two sentence summary.
Looking good, Eric This series shall be quite INTERESTING, to say the least
A good reiteration of an important aspect of nutrition. I feel for the guys that actually believe you can only absorb 25g prot at any given point in time...
I'd have to eat a ridiculous amount of meals everyday if I could only have 25g at each!
this is a really good idea. i think one to be examined would be pre and post workout nutrition. maybe not which one is best, but the science behind the different methods people use.
very nice article.
can i recommend the next one? how about soy and estrogen in men DURING PCT. many articles have debunked soy in men, and its estrogen conversion, but what makes women different here? is it the test-estrogen levels, and if so, is it wise for men to use soy products during PCT?
Well, that was well worth my time. Thanks for the excellent read!
Subscribed for further information/discussion.
Very nice write-up Easy...
And you're right, it's disappointing that there aren't any studies more closely related to real world applications. Whether it be carb and/or fat intake along with protein or even a wider variety of protein. You'd think think that one of the most essential aspects of bodybuilding would be studied a bit more....
Subbed for future issues.
Good first topic, some guy told me the same story. And I called bs in my head and researched it myself previously.
Do one on the importance of pumps in the gym.
Albiet, I still will believe its very important even if u disprove it.
Nice work My only comment is to throw in a line reminding people that we all are genetically different, and that individual ability to digest/utilize protein varies. Just because Gaston ate a dozen eggs doesn't mean you should
what about side effects of massive amounts of protein, ie liver and kidneys that have to process it?
phyto estrogens effect on SHBG and Testosterone.... how one effects the other ect, that would be an AWESOME READ , ill supply u with a great article too.
Breaking the Myth: "If I lift heavy I’ll end up looking like a man"
Breaking the Myth: "If I lift heavy I’ll end up looking like a man"
Rosie Chee, BExSpSc
8 December 2008
You hear it time and again from females in and out of the gym, when it is suggested to them that they either a) lift weights, or b) increase the weight that they are lifting. "I don't want to do that, because I don’t want to look like a man." Many people, males included, have come to believe that for a female to lift weights means that she will somehow transform into the stereotype image of the female bodybuilder. This is simply NOT the reality of females and resistance training. This article will discuss and compare the physiology, the hormonal adaptations to resistance training, and the role of diet in gaining muscle, in both males and females.
Whilst males and females are structurally similar, there are many physiological differences that affect the sexes’ ability to gain muscle mass.
The primary reason that females cannot gain muscle mass as fast or to the extent as males is the difference in hormone status.
Testosterone is one of the androgenic hormones responsible for anabolism in the body (Kraemer & Ratamess). It is testosterone that is responsible for masculine traits (i.e. excess hair (especially facial), deepening of voice, increase in muscle mass). Both males and females produce testosterone, as it is necessary for hormonal balance and body function (Marieb, 2004). However, males have much HIGHER levels of testosterone than females, with the 'normal' range of total testosterone (in the bloodstream) being 0.95-4.3 pg/dl, compared to the 0.7-3.6 pg/dl of females. However, it is not so much the total amount of testosterone that an individual has that determines their potential/ability for muscle growth, since most of the testosterone in the body is bound to either sex hormone binding globulin (SHBG) or other non-specific proteins such as albumin (Wheeler, 1995), but their levels of FREE testosterone (i.e. the amount of testosterone that is NOT bound in the body). In males 0.3-5% (with an average of 2%) of their total testosterone if free, with their free testosterone normal values being 270-1100 ng/dl, compared to only 6-86 ng/dl of free testosterone available to females.
The female 'equivalent' of testosterone is estrogen (Marieb, 2004). Whilst estrogen may increase Growth Hormone (GH), it also increases a) SHBG, which decreases the amount of free testosterone in the body; and b) cortisol, which reduces muscle mass (Hakkinen, 1989).
Muscle Fibres and Types
There is a similar distribution of the percentage of Type I, Type IIa, and Type IIb muscle fibres in both males and females. However, females have ~60-80% of the muscle cross-sectional area (CSA) and whole muscle anatomical cross-sectional area (ACSA) than that of males. Therefore, despite the potential for muscle hypertrophy in a relatively short period of time (Gregory, Stephen, Frederick, & & Lemmer, et al., 2006), similar percentage increases in either muscle mass or volume as a result of resistance training, results in smaller total overall gains in CSA and ACSA in females than in males (Folland & Williams, 2007).
Resistance Training and Hormonal Adaptations
Studies have shown that resistance training acutely increases total testosterone in males (Hakkinen & Pakarinen, 1995); whereas there is NO change in females. However, free testosterone HAS been shown to be elevated up to 25% in females after resistance training (Nindl, Kraemer, Gotshalk, & Marx, et al., 2001). Yet, because females have less free testosterone than males at rest, any increase is not significant enough to allow for muscle hypertrophy to the extent of a male. Therefore, it has been suggested that other anabolic hormones, such as GH may be responsible for hypertrophy in females (Kraemer & Ratamess, 2005).
Role of Diet in Gaining Muscle
Diet is an important component of gaining muscle mass. To gain muscle mass one needs to be eating MORE than Maintenance calories. Because females are generally smaller than males (i.e. smaller bone size and mass, less muscle mass, etc.), they generally require (and eat) LESS than males. If a female ate the amount that a male ate to gain mass, they would most likely end up gaining a lot of unwanted bodyfat along with muscle hypertrophy. Females are also generally more prone to eating disorders such as anorexia and bulimia, etc. that are detrimental to muscle hypertrophy, and cause muscle loss (Beals & Houtkooper, 2006).
Masculinization in females does not occur as a result of [heavy] weight training, but rather because of the excess of androgenic hormones (i.e. testosterone) coupled with the correct stimulus for muscle growth (i.e. chronic resistance training AND diet directed at muscle growth). The stereotype image of the female bodybuilder in the media is a result of said females chronically using androgenic compounds (i.e. steroids) in order to increase their muscle mass and size. For the female who is NOT doing this, they can lift as hard and as heavy as they want, and will come nowhere close to "looking like a man".
Beals, K. A. & Houtkooper, L. (2006). Disordered eating in athletes. In L. Burke & V. Deakin (Eds.). Clinical sports nutrition (3rd ed.). (p. 201-226).
Folland, J. P. & Williams, A. G. (2007). The adaptations to strength training: Morphological and neurological contributions to increased strength. Sports Med, 37(2). (p. 145-168).
Gregory, F. M., Stephen, M. R., Frederick, M. I., Lemmer, J. T., Tracy, B. L., Hurlbut, D. E., Metter, E. J., Hurley, B. F. & Rogers, M. A. (2006). Age and sex affect human muscle fibre adaptations to heavy-resistance strength training. Exp Physiol, 91(2). (p. 457-464).
Hakkinen, K. (1989). Neuromuscular and hormonal adaptations during strength and power training: A review. J Sports Med Phys Fitness, 29. (p. 9-26).
Hakkinen, K. & Pakarinen, A. (1995). Acute hormonal responses to heavy resistance training in men and women at different ages. Int J Sports Med, 16. (p. 507-513).
Kraemer, W. J. & Ratamess, N. A. (2005). Hormonal responses and adaptations to resistance exercise and training. Sports Med, 35(4). (p. 339-361).
Marieb, E. N. (2004). Human anatomy & physiology (6th ed.). San Francisco, CA, USA: Pearson Benjamin Cummings.
Nindl, B. C., Kraemer, W. J., Gotshalk, L. A., Marx, J. O., Volek, J. S., Bush, J. A., Hakkinen, K., Newton, R. U. & Fleck, S. J. (2001). Testosterone responses after resistance exercise in women: Influence of regional fat distribution. Int J Sport Nutr Exerc Metab, 11. (p. 451-465).
Wheeler, M. J. (1995). The determination of bioavailable testosterone. Ann Clin Biochem, 32(4). (p. 345-357).
BROSCIENCE BUSTED: Unless a female is chronically using androgenic compounds (i.e. steroids) with the appropriate training stimulus and a diet targeted towards muscle hypertrophy, then a female CAN LIFT WEIGHTS AND LIFT THEM HEAVY AND NOT EVER LOOK "LIKE A MAN"!!!
rosie, this is by far one of the best posts ive EVER seen on AM. no joke. i cant tell you how long it took me to convince my girlfriend that she could train for hypertrophy and not look like a man haha
i explained it a little simpler, by comparing guys who train and train and eat and eat and still have trouble putting on muscle. and if it were that easy to get huge, EVERYONE would be huge haha
reps for sure!
As I have said before, I prefer training males, because you can tell them straight what's what and they listen. Most females just want to know that they can just do cardio and either eat nothing or what they like and look like a 'fitness' model.
So, KEEP telling her. If she doesn't believe you, get her to take a look at some of my pics; I'm only 5'2", 110lb, and I train harder and lift heavier than most guys I know, and in no way do I look "like a guy"!
My girlfriend is always saying,"I don't wanna bulk up". Perhaps, this will finally convince her that it is not the case!! Thanks!!!
Think training's hard,. try losing!
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