took this from IFL..great read.
Originally Posted by Blown_SCThe Protein Bible
By: John Berardi
The issue of protein intake has been a source of much controversy among medical doctors, registered dieticians, nutritionists, scientific researchers and, of course, all kinds of athletes.
It is my strong opinion that "the great protein debate" was resolved in the 90's when numerous well controlled research studies demonstrated that both strength and endurance athletes needed more protein than had been predicted by energy equations and by simple nitrogen loss measures. Actually, the research studies have become abundant.
Athletes universally believe that high-protein diets increase performance and or muscle mass. Although this could just be a strong placebo effect, I think there may be some validity to these claims. First, the high protein intakes could lead to a strong positive nitrogen status which, when combined with rigorous strength training, may potentiate the growth process. Secondly, there are several other nutrients in high protein foods that could enhance performance and/or hypertrophy. Although there are few data on this second point, some obvious nutrient possibilities include creatine, specific amino acids (perhaps one or several of the BCAAs), conjugated linoleic acid, and/or some other unknown growth factor(s) that remain(s) to be determined [Peter W.R. Lemon, Ph.D. Nutrition and Exercise Laboratory, University of Western Ontario, ON, Canada].
Protein Need vs. Optimal Protein Intake
Conservative research studies are designed to figure out how much protein is needed to prevent deficiency. While a deficiency will probably lead to a loss in muscle mass and/or a loss in athletic performance, eating just enough protein to prevent a deficiency may not exactly lead to the best possible performance.
Numerous well - controlled research studies have been done to determine the exact amount of protein needed in athletes and weightlifters to achieve nitrogen balance. Nitrogen balance occurs when the amount of protein that goes into the body is equal to the amount that leaves the body (through urine, sweat, feces, etc) [Peter Lemon, Ph.D., and Mark Tarnopolsky, M.D., Ph.D.,. have conducted some of the best research in this area [Lemon et al. 1981, Lemon, 1997, Tarnopolsky et al. 1988, Tarnopolsky et al. 1992]. The results of these studies have demonstrated that both endurance and strength athletes often require more than double the protein of the average sedentary person (see Figure 1)].
In Figure 1, different protein intakes were compared and the resulting nitrogen balances were reported. These data tell us that endurance athletes need at least 0.54-0.64g/lb. while strength athletes need at least 0.77-0.82g/lb. to achieve nitrogen balance.
Recall that the recommended daily allowance (RDA) for protein has been set at ONLY 0.36g/lb. (0.8g/kg).
Many athletes are convinced that even higher levels of protein consumption beyond what Drs. Lemon and Tarnopolsky recommend will definitely impact muscle mass if not performance!
A 200-lb. strength athlete who desires to maintain body weight and prevent protein deficiency should eat approximately 154-164g of protein per day. Eating enough total calories is important as well, because protein needs are affected by many factors including: the type of training that you do (endurance vs. strength), your training history and your total calorie intake. Basically the fewer calories you are eating, the more protein your body needs to stay in balance or to achieve positive status [Lemon, 1995].
Some people have speculated that testosterone and anabolic steroid users will benefit from increased protein intake above the 1.5-2.0g/kg that Dr. Peter Lemon recommends for natural weightlifters. I certainly believe it's a distinct possibility that some supplements require a protein intake beyond current recommendations to exert noticeable effects. Any drugs or supplements that may have an impact on anabolism may require a higher protein intake [Tim Ziegenfuss, Ph.D. Human Nutrition Laboratory, Kent State University, Ohio, USA. Director of Research and Education, Phoenix Laboratories, New York, USA].
Seeking Maximum Muscle Mass
But what athletes want maximum muscle mass? Again, looking at Figure 1, it is evident that increased protein intakes above those needed to prevent deficiency will lead to a greater positive nitrogen status. Although at these high levels of protein intake, both total body protein synthesis and protein breakdown are increased, the amount of protein that stays in the body is usually higher at the higher protein intakes (up to a point).
Lemon has suggested that intakes over 0.82g/lb.-0.90g/lb. (1.8-2.0g/kg) may not be beneficial despite the apparent increases in positive nitrogen status. He believes that a ceiling may exist that prevents more muscle gain when eating above this level [Lemon, 2000]. One of the studies supported this in that although nitrogen balance was greater in subjects consuming 1.2g/lb. (2.6g/kg) vs. those consuming less protein for an 8-week weight training period, the higher protein group was no bigger [Tarnopolsky et al. 1992]. However, maybe this was due to the short duration of the study rather than the inability of higher protein to increase muscle mass.
Lemon tends to agree in at least one case, and suggests that when using anabolic agents (i.e. growth hormone, testosterone, etc), a high-protein intake may be necessary to maximize muscle gains [Bhasin et al. 1996, Lemon, 2000].
It's well accepted in the weight lifting community that during anabolic steroid use, protein intake should be around 2g/lb. (4.4g/kg). (So a 200-lb., hard training bodybuilder also using AS and GH might use 400 grams of protein a day)!
Going back to our 200-lb. natural strength athlete looking to increase muscle mass, I suggest that he/she might benefit from 182g of protein per day. The research is unclear whether more protein may further produce muscle gains, however, anabolic steroids theoretically increase nitrogen retention and, therefore, protein requirements.
Protein Intake: Performance Or Mass?
Athletic performance is dependent on many factors including skill level, conditioning, and team or individual strategies. Certainly, lack of nourishment will decrease performance but eating an excess of protein, carbohydrate, or fat might not increase performance (unless you are a strength and power athlete). Studies examining whether very high protein intakes can enhance a variety of athletic performance have not been promising [Lemon, 2000].
The bottom line is that it appears better to over-eat than to under-eat protein when someone's trying to add muscle mass while keeping body fat off. Excess protein calories are not as likely to be stored as body fat compared to carbs and most fats. This is because the metabolism and processing of protein is energy costly endeavor in that it's more thermogenic and activates hormones that help with fat loss [Lonnie Lowery, PhD. Human Nutrition Laboratory, Kent State University, Ohio, USA].
Carbohydrates make up the predominant energy source for most athletic activities. In general, only a small amount of protein is burned for energy during exercise. In fact where normal diets are consumed, it is only significant (5-15% of total calories burned) for long duration endurance training [Dohm et al. 1982, Lemon and Mullin 1980, Lemon et al. 1983, Yarasheski and Lemon, 1983]. High levels of blood or muscle protein don't immediately contribute to the energy needs of exercise modes.
However, while protein is not a great pre-game meal, athletes usually follow year-round intense training programs. Recovery from these intense training sessions is necessary to see continual progress. Therefore, from a recovery perspective, protein intake may be as important, or more so, to the athlete as the other macronutrients.
Will a high protein diet increase muscle mass? Yes. But, will this increase performance? Since many athletes believe in the power of protein to increase muscle mass, more studies need to be done. However it only stands to reason that if muscle mass is increased due to long-term high protein intakes, athletes involved in strength and power sports will undoubtedly receive a benefit over time.
Benefits Of Increased Protein Beyond Athletic Performance
While high protein diets may not necessarily improve athletic performance (beyond recovery considerations) and it's nor proven that protein above 0.82g/lb. (2g/kg) will increase muscle mass, are there any other benefits of a relatively high protein intake? I think the answer to this question is yes.
Protein and Metabolic Rate
Protein intake may positively affect body composition. Since all food requires metabolic processing, all macronutrients increase metabolism. However, the metabolic increases seen when eating protein are double those seen when eating carbohydrates or fat. Therefore a high protein intake may in fact be thermogenic and may lead to increased calorie burning and fat loss.
During dieting, this may enhance calorie expenditure and therefore the rate of fat loss [Blacklevin et al. 1975, Ballor and Poehllman 1994, Skov et al. 1999, Alford et al. 1990]. As I said above, more protein is needed on a low calorie diet anyway; especially when working out. During overeating in an attempt to gain muscle, although higher protein intake may not be needed for positive nitrogen status, it's likely better to eat excess protein rather than carbohydrates or fats. Since overeating leads to both some muscle and some fat gain, eating more calories as protein may lead to more lean weight and smaller gains in fat weight.
Did you know that eating protein might increase your metabolic rate and nutrient balance? By virtue of this phenomenon, a higher protein diet may contribute to body fat losses. Since protein foods require more "metabolic processing" than carbohydrates and fat it only stands to reason that the metabolic increases seen when eating protein would be higher than those seen when eating fat or carbohydrate. In fact, several research investigations have shown just that. The metabolic increase seen with eating protein is just about double that of eating carbohydrates or fats [Welle et al. 1981, Robinson et al. 1990, Nair et al. 1983].
Protein and Hormones
In addition to the calorie burning effects of protein, higher protein intakes can increase the release of the hormone glucagon from the pancreas [Guntiak et al. 1986, Linn et al. 2000)]. The hormone insulin prevents fat loss from adipose (fat) tissue, but glucagon is responsible for reversing this effect [Yamauchi et al. 1988]. Glucagon also does a nice job of decreasing the enzymes responsible for making fats and building up the fat stores in the liver and in the fat cells [Girard et al. 1994].
So again, higher protein intakes may lead to losses in body fat due to the thermogenic effects as well as the hormonal effects of eating protein. During dieting, this may lead to a greater rate of fat loss [Blacklevin et al. 1975, Ballor and Poehllman 1994, Skov et al. 1999, Alford et al. 1990]. And, during overfeeding, it may lead to a smaller increase in fat mass relative to lean mass gains.
Additionally, in applicable human studies, protein and branched-chain amino acid supplements have been shown to increase the igf-1 response to eating and to exercise [Kraemer et al. 1998, Thissen et al. 1994, and Carli et al. 1992]. Therefore both protein and calorie intake may be responsible for raising igf-1 levels. Since igf-1 can regulate the muscle growth [Adams 1998], I believe that a high protein intake may assist in muscular development.
Protein and Cardiovascular Disease Risk
Finally, increasing the percentage of protein in the diet while decreasing the percentage of carbohydrates and fats may have some real health advantages. Increasing protein intake from 11% to 23% can lead to very favorable changes in blood lipids and cardiovascular disease risk.
So, there may be some real health and body composition benefits to higher (even "excessive") protein intakes. More research on these topics is needed but until this research is done, the reports of hundreds of athletes, bodybuilders, and weightlifters have confirmed my speculation.
We have data showing that increasing protein intake from about 10 to 20% while decreasing carbohydrate intake from 55 to 45% (with fats kept constant at 35%) can lead to favorable changes in blood lipids. However, with athletes, increasing protein to levels higher than 20% might not offer much more benefit in terms of blood lipids and may actually decrease performance since either carbohydrate and/or fat would have to be reduced in order to do so. For the majority of athletes, since carbohydrates and fats are essential for athletic performance, I would not recommend decreasing either in favor of more protein [Len Piche, Ph.D, RD. Nutrition Program, Brescha College, University of Western Ontario, Ontario, CA].
Safety of A High-Protein Diet
In the previous section I suggested that not only a high protein intake, but also an excess protein intake might have some benefit to those interested in changing body composition and decreasing cardiovascular disease risks. Again, an important distinction has to be made. High protein diets aren't necessarily in excess. In fact, according to the data discussed earlier, high protein diets in athletes are just enough to get these individuals to nitrogen balance. So this isn't an excess of protein at all!
Replacing Carbs with Protein
Why are nutritionists recommending high carbohydrate diets when research has demonstrated that replacing some dietary carbohydrates with protein can lead to favorable blood lipid profiles?
Dr B.M. Wolfe, a nutrition researcher at the University of Western Ontario, has been asking himself this very question for several years. In three separate studies, Dr Wolfe has shown that when increasing protein intake from about 11% of the diet to about 23% of the diet, blood markers associated with heart disease took a turn for the better [Wolfe and Piche, 1999, Wolfe, 1995, Wolfe and Giovannetti, 1991]. This benefit occurs in both healthy and high-risk people.
As the protein intake increased, Dr Wolfe made sure that the fat content of the diet stayed the same (25-35% fat) while the carbohydrate content was reduced (from about 63% to about 48%).
The exact magnitude of the changes was pretty large as in one particular study, the bad fats like LDL cholesterol decreased by between 6% and 9%, while the good fats like HDL cholesterol increased by between 12% and 17% [Wolfe, 1995]. In addition, in this study, the ratio of plasma total cholesterol to HDL cholesterol (the lower the ratio the better) decreased by between 15% and 16%. Finally, in this study, the total triglyceride levels decreased by between 18% and 23%.
Another interesting effect of the protein increase in these studies was that the satiety levels of subjects tended to be higher with the high protein diet. Therefore they felt fuller at the same calorie intake. Protein is well known to have this effect on appetite.
Protein and Kidney Strain
The kidneys ultimately process chemicals derived from protein breakdown. Because of this, some have theorized that extra protein break down could cause strain and therefore damage to the kidney. From the research, though, there is no data (in healthy rats or in healthy humans) that support such theories.
In fact a new study directly contradicts this theory. In this study protein intakes up to 1.27g/lb. (or 2.8g/kg) did not cause kidney damage. Some rat studies have revealed that when rats were given an 80% protein diet for long periods of time, none of the rats showed any signs of kidney damage [Zaragoza et al. 1987].
Protein and Osteoporosis
Past research has revealed that high protein intake was associated with increased calcium loss in the urine. From this researchers thought that this could lead to osteoporosis. Recently, though, such concerns have been dismissed. Recent studies have shown that higher protein intakes usually lead to a higher bone mineral content instead [Cooper et al. 1996, Freudenheim et al. 1986]. Since exercise is known to increase bone mass, a high protein diet coupled with exercise training leads to a net increase in bone mass despite any potential losses in calcium.
The Purported Hazards of Eating Lots of Protein
So what is the truth? Are high protein diets dangerous? Look and see what the research has to say.
Impaired Kidney Function?
Although studies have been published showing that in individuals with unhealthy kidneys, an excessive protein intake could place undue strain on their kidneys, healthy individuals have little to worry about with high protein diets. To demonstrate this, a recent study revealed that when bodybuilders consumed up to 1.3 grams of protein/lb. (2.8g/kg) of body weight kidney function was not impaired [Poortmans and Dellalieux 2000]. In fact, in an older study conducted with female rats, kidney function seemed to be improved with high protein diets [Sterck et al. 1992].
A few original studies demonstrated that when protein intake was raised to 140-225g per day, excess calcium was lost from the urine at a faster rate than normal [Hegsted et al. 1991]. However, in these studies, calcium intake as well as phosphorus intake was restricted and not allowed to increase in proportion to the protein intake. Since whole-food proteins contain both calcium and phosphorous and even protein supplements are fortified with calcium and phosphorous, it only makes sense that increases in protein intake are typically accompanied by increased dietary calcium and phosphorous. In this scenario, the research has demonstrated that when taking in additional protein, there is actually a positive calcium balance and there are no adverse affects on bone calcium content [Hegsted et al. 1991, Zigler and Filer, Jr. 1996, National Academy of Sciences National Research Council 1989].
If protein supplements are used, they should be fortified with calcium and phosphorous.
There is no doubt that maintaining protein synthesis rates is a major problem for a high-volume/high-intensity endurance athlete (one of the reasons why anabolic steroid use is prevalent in pro cyclists). Metabolically speaking, these athletes spend much of their day in a major catabolic state. Therefore I think it is vital that these athletes be well on the positive side of nitrogen balance (closer to 2g/kg) to ensure that the massive daily calorie expenditure doesn't negatively impact lean muscle mass. However, too much protein (above 2g/kg) can be a problem for endurance athletes since it can change the acid/base balance of the body - decreasing the ability to sustain high intensity activity, or it may replace much needed carbohydrates in the diet [Eric Noreen, MS, PhD candidate. University of Western Ontario, ON, Canada].
Whole Foods vs. Supplemental Protein
Athletes and nutritionists have been arguing for years about whether or not protein supplements are necessary. Nutritionists argue that protein needs can be met by whole food sources. They also say that supplemental protein powders offer no advantages. I don't necessarily agree with the nutritionists on this point.
Clearly, it is more "fun" to eat a 16-ounce filet mignon than a can of protein. But protein supplements can offer significant advantages over whole food sources.
Variety and Convenience
Most athletes and nutritionists will certainly agree that protein intake should come from a variety of sources. Different protein sources have different amino acid, vitamin and mineral profiles. The consumption of a limited variety of any macronutrient (protein, carbohydrates, or fats) or micronutrient (vitamins or minerals) can lead to nutritional deficiencies. So how does one prevent deficiency? Eat variety! Mainstays of the diet should be protein sources like lean beef, eggs, low fat cheese, milk, fish, and chicken.
But, typically athletes choose protein sources that are convenient and require minimal preparation (there goes the chicken, beef and eggs). In this scenario, because the protein sources are limited, the athlete doesn't eat enough of them. After all what 200-lb. guy wants to eat three whole containers of cottage cheese just to meet his 180-g protein requirement for the day.
In addition, food protein sources chosen for convenience may be missing certain amino acids necessary for growth and repair. If this happens, although the grams of protein eaten may seem to be adequate, there can be serious deficiencies in the diet. Specific amino acid deficiencies from a limited variety can impair normal function. An illustration of the complexity and importance of protein and amino acid transport in the body is illustrated in Figure 2. This figure also illustrates the complexity of protein metabolism.
Protein supplements often contain very high quality protein that requires no meal planning short of remembering to grab your protein packet or protein bar on the way out the door. In addition, since these protein powders are often fortified with vitamins and minerals (two other components of a balanced diet that many athletes are lacking), they may provide an easy source of other nutrients necessary for optimal nutrition and growth.
Protein Supplements and Cost
What about costs? Nutritionists have claimed that protein supplements are very expensive relative to their protein content and that whole food sources are cheaper. Not so.
As you can see, protein supplements, while slightly more expensive in some cases, are not substantially more expensive than whole food sources when compared per 40g of protein. Most supplemental protein powders that offer around 40g of protein, 24g of carbohydrate and 3g of fat are substantially cheaper (and certainly more nutritious) than the fast food meals that some individuals would choose over cooking 1/2 lb. of chicken or preparing a dozen egg whites. In addition, since many food sources contain other macronutrients, (carbohydrates and fats) if an individual is interested in increasing protein intake with a minimal increase in calories from other macronutrients, fat and carbohydrate-free protein powders are ideal.
Protein and Digestibility
Finally, another advantage of supplemental protein sources is that they are manufactured to be digested faster than whole protein sources. In addition to rapid digestion, a very high percentage of good protein powders are completely digested and absorbed due to the amino acid profiles of the supplements and the lack of lactose or fat. Today many supplemental proteins are also partially hydrolyzed (broken down) when processed. Therefore they require less natural GI processing before absorption.
Protein quality is measured in many different ways. Two of the most common are biological value (BV) and the protein digestibility corrected amino acids score (PDCAAS).
The BV score gives us an indication of how much of the protein eaten remains in the body (the rest is excreted via sweat, urine, feces). Since the BV score is measured relative to a high quality "test protein" (usually egg protein), the test protein is given a BV of 100. A BV score of 70% or greater is usually considered good quality protein.
The PDCAAS measures the individual amino acids in the protein. A deficiency in only one amino acid may cause dramatic negative consequences. Therefore, this measure of protein quality examines the essential amino acid content of the protein in question and compares it against the human requirement for essential amino acids. Since a protein is only as good as it's weakest link, the amino acid that is lowest in the protein source then is termed the limiting amino acid.
Wheat protein is known to be a poor quality protein due to the fact that its limiting essential amino acid is lysine. Since the lysine content of wheat protein is only 8mg/1g protein while the human requirement for lysine is 19mg/1g protein, this protein source only provides 42% (8 divided by 19) of the necessary lysine for growth and repair.
Animal products score better on both the BV and PCDAAS scales. This is why animal proteins are typically the proteins of choice for athletes. Other protein sources like beans, grains, and peanuts can be eaten but are usually insufficient to provide the body with the amino acids necessary for growth.
Due to the high quality protein in animal sources, researchers have examined whether animal protein is better for getting stronger, gaining mass and losing fat than vegetarian protein. From these studies it has been concluded that an omnivorous diet containing protein from several sources including various meats, eggs, and dairy is superior to a vegetarian diet containing no meat and only a small amount of dairy and eggs.
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