How Much Protein Do I Need?


This is probably the most common question I am asked as a dietitian. Whether someone is an elite athlete or a casual weight lifter, it seems they all want to supplement with this magic muscle powder. However, most of the population has major misconceptions about what protein is, how your body uses it, and how much you should be consuming.

complete-protein-incomplete-proteins

What Is Protein?

Protein is one of the three major macronutrients (along with carbohydrates and fat) that contain amino acids and nitrogen.  There are 20 different amino acids. The human body can synthesize 9 of the amino acids on its own (non-essential amino acids), but cannot synthesize the other 11 amino acids (essential amino acids) and need to be consumed through the diet. Thus, it is important to consume a variety of protein in your diet in order to have a balance of essential and non-essential amino acids. Proteins provide a variety of biochemical functions in the body.

Functions Of Protein

1. Energy – 1 gram of protein = 4 calories

2. Antibodies – to help defend again foreign pathogens (ex: Immunoglobulin G)

3. Muscle building and contraction – (ex: actin and myosin muscle fibers)

4. Messaging – protein hormones help send chemical messages throughout the body (ex: insulin, growth hormone)

5. Storage

6. Transport – transport proteins help move molecules to different parts of the body (ex: hemoglobin)

7. Structure – provide structure and support to cells

8. Enzymes – help to catalyze biochemical reactions (ex: lactase)

Daily Protein Requirements

The general population:            0.8 grams protein/kg body weight   OR  10-35% of total energy intake

Endurance athletes:                  1.2 – 1.4 grams protein/kg body weight

Resistance-trained athletes:    1.6 – 1.7 grams protein/kg body weight

*Key Point To Remember: These ranges are in KILOGRAMS of body weight, NOT pounds of body weight. (1 kilogram = 2.2 pounds)

Example – For an average 150 lb individual:   150 lbs x (1 kg/2.2 lbs) = 68 kg

68 kg x 0.8 g protein/kg body weight = 55 grams of protein per day

If you don’t feel like doing the calculations, below is a table of the RDA for protein by gender and age.

protein RDA

In general, Americans are consuming well over the RDA for protein. The graph below depicts the average amount of protein consumed by Americans. Throughout the lifespan, the amount of protein is consumed the greatest between the ages of 19-30 years old. Since I am a part of this age group, maybe that is why so many of my peers are asking me questions about how much protein they need.

Source: NHANES 2003-2004

Source: NHANES 2003-2004

Amount of Protein in Common Foods:

  • 1 oz beef = 7 g
  • 1 oz chicken breast = 9 g
  • 1 oz soft cheeses = 6 g
  • 1 oz medium cheese = 6-7 g
  • 1 oz hard cheese = 10 g
  • 1 oz tuna = 7 g
  • 1 cup soybeans = 29 g
  • 1 large egg = 6 g
  • 1 oz nuts = 9 g
  • 1 oz tofu = 2 g
  • 1 slice bread = 2 g
  • 1 slice bacon = 3 g
  • 2 TB peanut butter = 8 g
  • 8 oz milk = 8 g

How Much Is Too Much?

“The more protein I eat, the bigger my muscles will get.” This is not necessarily true. First of all, consuming an excess of calories, whether it’s via protein, carbs, fat, or alcohol…will be stored in the body as fat. Second of all, the human body cannot properly utilize protein beyond a certain amount.

The upper limit for protein is generally 2 grams protein per kg body weight.

protein lifter

Side effects of excess protein consumption include metabolic imbalance, toxicity, nervous system disorders, and kidney problems. When excess protein is consumed, your body uses more water in order to excrete it. For this reason, individuals consuming a high protein diet should also be consuming adequate water in order to prevent dehydration. High protein diets also tend to be higher in cholesterol and saturated fat, which can increase your risk for heart disease and stroke.

Does Whey Protein Aid In Muscle Building?

Please refer to one of my previous blog posts for an in-depth explanation behind the research on whey protein.

Bottom Line:

1. Most Americans consume far more protein than they need.

2. Consume a variety of different protein sources to get a variety of other nutrients.

3. Do not OVER supplement with protein, this can cause long-term damage to your kidneys as well as your wallet.

What is a “Certified Specialist in Sports Dietetics”?


For the past couple of weeks, I have been on a rotation with WVU’s Certified Specialist in Sports Dietetics (CSSD).  Many individuals do not realize what this certification means and the requirements to obtain this certification.

“The CSSD is offered by the Commission on Dietetic Registration (CDR) for registered dietitians (RDs) who have specialized experience in sports  dietetics. Being Board Certified as a Specialist in Sports Dietetics designates specific knowledge, skills, and expertise for competency in sports dietetics practice.”

The requirements to become a CSSD are as follows:

    • Current Registered Dietitian (RD) status by the Commission on Dietetic Registration.
    • Maintenance of the RD status, for a minimum of two years from the original examination date (by the date of the specialty examination).
    • Initial Certification: Documentation of 1,500 hours of specialty practice experience as an RD within the past five years (by the date the application is due).
    • Recertification: Documentation of 1,000 hours of specialty practice experience as an RD within the past five years by the date the application is due (effective until 2014).

 

What are the “Top 10 Reasons to Consult a CSSD?” Find out here!

 

“Assault” Pre-Workout Supplement


I have recently had a special request from an undergraduate student to blog about a specific nutritional supplement.  Like many other college-aged males, this student is physically active with an overall goal of increasing lean muscle mass and decreasing body fat. It is rare that I look into one specific brand or supplement, but he asked me to investigate the type of pre-workout supplement he uses, which is called Assault (sounds kind of scary, right?)

Traditionally, pre-workout supplements are consumed prior to training in the hope of enhancing focus, energy, and endurance during exercise as well as decreasing muscle fatigue post-workout.  Pre-workout supplements typically have an array of different ergogenic ingredients. When ingested together, these components are meant to work synergistically to enhance athletic performance. There are literally thousands of nutritional supplements being marketed to the public.  Therefore, athletes need to be wary of  exactly what they are putting into their body, the ingredients, the side effects, and the dosage.  What many individuals do not realize is that the Food and Drug Administration does not federally regulate nutritional supplements. Therefore, there is no 100% guarantee in regards to the manufacturer’s ingredients, nutritional claims, and safety regulations.

Assault Nutrition Facts

Assault is manufactured by MusclePharm in Denver, CO. It contains a vast variety of ingredients, thus making it difficult to pinpoint which ones specifically are the active ingredients that provide the greatest benefit.

One serving of Assault is half a scoop.  However, it is more realistic to assume that many athletes use one whole scoop at a time, making it twice the serving size.

One scoop (or 2 servings) provides:

  • 80 calories
  • 18 g carbohydrates
  • 28 mg Vit. B6 (1400% DV)
  • 170 mcg Vit. B12 (2833% DV)
  • 5 g creatine monohydrate
  • 6 g branched chain amino acids (BCAA)
  • 4 g beta alanine
  • Nitric oxide – Citrulline malate, L-arginine
  • 300 mg caffeine – That’s as much as about 3 cups of coffee…but imagine drinking them all at one time!

The main active ingredient in Assault is more than likely the caffeine content.  The other ergogenic ingredients are the B-vitamins and nitric oxide.  B-vitamins assist with energy metabolism, DNA synthesis, the formation and repair of red blood cells.  Nitric oxide (such as L-citrulline and L-arginine) increases blood flow and oxygen supply to skeletal muscles, which also helps the body to pump out the lactic acid that creates muscle soreness (4).

However, researchers state the creatine and beta-alanine in the supplement both require “loading periods” of ingestion over several weeks in order to provide the best effects. (3)

Proposed Claims and Possible Risks

A 32-serving tub of Assault will run consumers around $30-$40, which will last about a month if used 3-4 times per week. Many users rave about its drinkability because of it’s variety of flavors, such as green apple, blue arctic raspberry, raspberry lemonade, fruit punch, and watermelon.  In fact, bodybuilding.com dubbed Assault the “Best New Supplement of Year, 2011”.

Proposed Claims (1)

  • Fights muscle fatigue and decreases recovery time
  • Boosts performance
  • Builds lean muscle and decreases body fat
  • Amps up intensity
  • Increases focus and intensity
  • Hydrates muscles – From what I can tell, it really doesn’t “hydrate” your muscles. Instead, it will dehydrate your body because caffeine is a diuretic. In fact, the manufacturer’s recommend drinking a gallon of water a day while taking Assault.  In terms of electrolytes, it certainly doesn’t contain enough to have a hydrating effect…with one serving containing only ~1% DV for potassium and ~2% DV for sodium.

Possible Risks and Side Effects (the company suggests staying hydrated by consuming 1 gallon of water per day to avoid some of these side effects)

  • Fidgety – Probably due to the large dose of caffeine
  • Prickly or tingly feeling of the skin – Probably due to beta-alanine. There are two theories as to why beta-alanine causes itchiness of the skin. 1) Beta-alanine stimulates nerve receptors to trigger the firing of neurotransmitters at random, and 2) Beta-alanine perpetuates the response of nitric oxide, causing a person to literally “feel” the blood running through the capillaries that are close to the skin. (2)
  • Increased heart rate – Caffeine
  • Dizziness – Caffeine or dehydration
  • Headaches – Caffeine or dehydration
  • Trouble sleeping – Caffeine
  • Nausea

Down to the Science

A study published earlier this year investigated the effects of Assault on athletic performance.   The randomized, double-blind study was conducted by researchers at the University of Alabama, the University of Oklahoma, and the University of South Alabama. Twelve recreationally-trained males (average age of 28) participated in the three-week study. Participants were required to attend three separate training sessions. The first session consisted of baseline testing.  During the next two sessions, subjects were randomly assigned to ingest either 1 scoop of the Assault supplement or a placebo drink 20 minutes prior to exercise. The placebo was a flavored carbohydrate drink with similar color and flavor to the supplement.

Subjects were asked to perform exercises to determine 1 repetition max (1 RM) on the bench and leg press, 75% 1 RM on the bench and leg press repetitions to exhaustion, VO2 max, and various choice reaction time testing (which basically tested agility).  Participants were also asked to complete a subjective survey to describe feelings of energy, fatigue, alertness, and focus on a 5-point likert scale.

Results found that ingesting the Assault supplement 20 minutes prior to training provided significant increases only in leg press repetitions to exhaustion, perceived energy, alertness, focus, and some agility exercises.  Most of the benefits of the supplement were seen in anaerobic exercises with no significant increases seen in aerobic endurance performance. (3)


PROs of this study:

  • It was a randomized, double-blind study, meaning neither the researchers nor the participants knew the contents of the drink at that particular time.
  • The researchers were not funded by the manufacturer.
  • The supplement and placebo were similar in color, taste, and size.
  • Subjects completed a 2-day food diary prior to the second training day in order to calculate caffeine intake from other sources.

CONS of this study:

  • Small sample size of only 12 participants.
  • Participants were all male, with no females.
  • Short time period of only 3 weeks
  • Participants were all recreationally trained (with strength values in the 75th and 90th percentile in the bench and leg press 1 RM and VO2 max in the 60th percentile).  It would have been interesting to observe the inclusion of individuals with varying levels of physical activity to see if there are differences in benefits based on a person’s baseline fitness level.
  • According to the 2-day food diaries, subjects consumed an average of 31.5 + 109.4 mg of caffeine per day through other food sources in their diet. To give some perspective, a 12 oz can of Coke contains 35 mg of caffeine and a cup of coffee can contain up to 100 mg of caffeine.  Thus, men who consumed larger quantities of caffeine on a daily basis may not have experienced the same effects of the supplement due to increased tolerance.

What’s the bottom line?

As a nutrition professional, my opinion is always to avoid taking any unnecessary supplements and to get proper nutrients from whole food sources. That being said, Assault DOES seem to work. In the study described above, participants felt more energized and alert during training sessions and the men were able to perform more leg press repetitions compared to the placebo.  The main effect of Assault is most likely due to the high caffeine content. For this reason, habitual caffeine users may not experience the same effects as non-caffeine users due to a higher tolerance. My concern with caffeine is the dangers it has to the body as well as the heart…ESPECIALLY when someone is exercising and their heart rate is increased to begin with.  I also do not like the fact that several users claim to feel “tingly” or “itchy” while using this supplement. I’m no doctor, but I’d say that definitely isn’t normal and definitely isn’t a good thing.

 

Sources:

1.       www.gnc.com

2.       http://www.cnpprofessional.co.uk/blog/?p=186

3.      Spradley, et al. Ingesting a pre-workout supplement containing caffeine, B-vitamins, amino acids, creatine, and beta-alanie before exercise delays fatigue while improving reaction time and muscular endurance. 2012. Nutrition & Metabolism, 9:28.

4.      http://www.nutritionexpress.com/showarticle.aspx?articleid=286

Coconut Water – It’s Mother Nature’s Sports Drink!


In the past few months, I have been noticing coconut water creating quite a buzz in the nutrition-world. I never really heard much about coconut water until I saw a few of my friends downing the drink after an intense workout.  We aren’t stranded on a desert island, here…so why in the world are people drinking this stuff?

As it turns out, the drink has many proposed health benefits such as being an excellent source of hydration and electrolytes, and preventing kidney disease, heart disease, and aging. Hm, are these claims about coconut water valid, or is it just another hyped-up marketing scheme?

What is Coconut Water?

Coconut water is the clear liquid from the inside of immature or green coconuts. This is not to be confused with fatty coconut milk, which is squeezed from the grated meat on the inside of a coconut. In general, coconut water contains more potassium, less sodium, and less calories than sports drinks.

The PROS of Coconut Water

  1. Loaded with electrolytes – Coconut water is referred to as “mother nature’s sports drink” due to it’s electrolyte content. As you can see by the nutrition facts label below, it is loaded with potassium, sodium, chloride, magnesium, and calcium. Electrolytes are especially beneficial after exercise and physical activity because many electrolytes, especially potassium and sodium, are lost through sweat. The most abundant electrolyte in coconut water is potassium.  Did you know that 1 cup of coconut water contains 600 mg of potassium…which is more than a banana or an avocado?!
  2. Hydration – Perfect for rehydrating post-workout and can even alleviate those horrible hangovers! Professional tennis player John Isner swears by coconut water during his famous 11-hour Wimbledon win. He states, “It is super hydrating and has kept me going in long matches and prevented me from cramping even in the hottest and most humid conditions”,
  3. Low in calories – Containing only 46 calories in a 1 cup serving, coconut water is much lower in calories compared to many other commercial sports drinks (which can contain up to 250-300 calories).  Thus, coconut water may be a great option for individuals who need extra hydration for various health reasons, but don’t want to pack on the pounds with extra calories.
  4. Fat free and cholesterol free – Coconut water has NO cholesterol, NO fat, NO saturated fat, and NO trans fat…enough said.
  5. It’s natural – Coconut water comes strictly from nature with no chemical additives or added sugars. The 9 grams of carbohydrate in coconut water comes from simple, natural sugars…as opposed to refined and added sugars that are commonly found in processed foods and drinks.

Nutrition Facts Label for 1 cup of coconut water.


The CONS of Coconut Water

  1. Price – Compared with commercial sports drinks, coconut water tends to be more expensive.  Depending on the manufacturer and the brand, coconut water runs around 15-18 cents per ounce, whereas Gatorade runs around 5-8 cents per ounce.
  2. Quacky claims – Sorry, but downing gallons and gallons of coconut water is not going to cure you of diabetes, stave off cancer, make you look 20 years younger, or any of the other quacky claims you may see in the media.
  3. Taste – Some brands may vary in taste. Does coconut water taste as good as a sports drink? Well, that is strictly a subjective assessment. Because sports drinks offer a variety of sugary, artificial, and exotic flavors, the chances of consumers finding a sports drink they like may be more realistic than someone liking the single flavor of coconut water.
  4. May not be appropriate for ELITE athletes – Elite athletes or individuals who sweat profusely for over 3 hours lose a VAST amount of potassium and sodium.  Esteemed sports nutritionist, Nancy Clark, MS, RD, suggests neither coconut water nor sports drinks contain enough sodium or carbs for someone who is sweating profusely.  She states, “Supplement with a quick source of energy like a banana or some raisins and a handful of pretzels to provide nutrients to replenish your stores”.

What’s the bottom line?

If you’re an active person who doesn’t mind the taste or price of coconut water, it could definitely be worth it. Coconut water is completely natural and void of the added sugars and additives in many sports drinks.  Coconut water is also high is potassium, low in sodium, and low in calories and fat.

Sources:

http://www.nutritiondata.com

http://phenomwater.com/top-10-coconut-water-nutrition-facts

http://health.usnews.com/health-news/diet-fitness/heart/articles/2009/08/10/do-coconut-oil-and-coconut-water-provide-health-benefits?page=2

http://www.webmd.com/food-recipes/features/truth-about-coconut-water?page=2

Whey Protein, “Whey” Worth It


Consumption of sufficient dietary protein along with a resistance exercise program has been shown to increase muscle mass.  The average person requires about 0.8 g protein/kg body weight.  However, many athletes have a much higher requirement for protein from 1.2-1.7 g protein/kg body weight.  I always believe that consuming nutrients through food is much more beneficial than relying on supplements.  However, many athletes find it difficult to consume this high amount of protein that their body requires strictly through food sources.  Thus, many athletes resort to protein supplements and powders as an extra addition of protein. Specifically, whey protein is extremely popular amongst athletes and active individuals.  In fact, a 2001 study reported that 50% of college freshmen football players believed that protein supplementation was necessary to increase muscle growth (12).  Although, the specific sources and types of dietary protein that are most beneficial to the body has been a hot topic for debate. Therefore, I chose to delve into some of the research on whey protein and come to a conclusion based on science.

Whey protein is a popular supplement for athletes trying to build muscle mass.

What is Whey Protein?

Whey protein in particular has been a preferred source of protein, over other sources such as casein and soy, because it is fast acting, quickly digested, and has a high branched chain amino acid content (BCAA) (1).  The BCAA’s (leucine, isoleucine, and valine) are used as fuel for muscles during exercise, stimulate protein synthesis, and improve muscle recovery time.  In recent years, whey protein has been a popular ergogenic aid in those attempting to increase muscle mass. Contributing to 77% of domestic powdered protein sales in 2004, whey has been a popular source of protein because of its BCAA composition, it’s ability to synthesize protein and increase muscle mass, it is easily available on the market, and has a desirable taste.  The market price of whey protein varies greatly depending on the manufacturer and the purity of the whey protein and can run anywhere from $10-$30 per pound.  Whey is produced during the process of cheese making throughout the separation of the curds and the whey.  The curds contain the component casein and the translucent liquid byproduct contains the whey protein. Once consumed, whey protein reaches the small intestine very quickly and rapidly, but once in the small intestine, hydrolysis requires a longer amount of time compared to casein, thus allowing for a greater absorption rate (3).

Forms of Whey Protein

1.  Whey protein isolate: This is the “purest” form of whey protein. It contains the most amount of protein per serving (90%+ protein by weight), has the highest bioavailability compared to other forms of whey, and has very little carbs and lactose. The downside to isolate is it is usually pretty expensive.

An example of a nutrition facts label for whey protein isolate.

2.  Whey protein concentrate: Concentrate is not as pure as isolate, containing 29%–89% protein by weight. The downside is that concentrate has more calories from fat and has a slightly higher amount of carbs and lactose. However, whey protein concentrate tends to be decently priced.

An example of a nutrition facts label for whey protein concentrate.

3.  Whey protein hydrolysate: This is predigested and partially hydrolyzed to aid in easier digestion and metabolism.  The hydrosylate form also produces less of an allergic reaction, which is beneficial to people with lactose intolerances.  However, it is usually more costly.

Does Whey Protein Increase Muscle Mass as a Supplement to Resistance Exercise?

Based on peer-reviewed research, whey protein is considered an excellent source of protein (Grade A = Strong positive scientific evidence).  It is also considere to be beneficial in increasing muscle mass and as an aid in weight loss (Grade B = Positive scientific evidence).  The grading system reflects the level of available scientific evidence (13).

Protein supplementation from whey has been shown to increase muscle mass more efficiently than other protein sources. In a study by Kerksick et al., 36 males participated in resistance training 4 days/week over a ten week period. The participants were randomly assigned into one of three supplement groups in a double-blind study; a carbohydrate placebo (48 g/d), whey protein (40 g/d) plus casein (8 g/d), or whey protein (40 g/d) plus BCAA’s (3 g/d) and L-glutamine (5 g/d).  Results showed that after 10 weeks, the group that received whey protein plus casein had greater significant increases in 1 repetition maximum leg press, bench press, lean mass, and fat free mass than the placebo group (4). In another study by Andersen et al., twenty-two healthy males were given either a protein supplement drink or a carbohydrate drink immediately before and immediately after each resistance training session as well as one drink on non-training days. The protein drink contained 25 g of protein (16.6 g whey, 2.8 g casein, 2.8 g egg white protein, and 2.8 g of L-glutamine).  Resistance training was performed three times per week for fourteen weeks and included 3 to 4 sets of inclined leg press, isolated knee extension, and hamstring curls for 4 to 15 repetitions maximum. The results showed that Type I and Type II muscle fibers in the trained leg muscles had an 18% ± 5% (P < .01) and 26% ± 5% (P < .01) increase respectively, whereas the carbohydrate group showed no significant increases in muscle fibers (5).

Another study observed the effects of whey protein in short term exercise. Eighteen men were given either a whey (21.4 g), casein (21.9 g), or soy protein (22.2 g) sports drink (all ~100 kcal) after performing four intense unilateral leg exercises.  Consumption of the whey protein drink produced greater muscle protein synthesis both at rest and after exercises compared to casein and soy (6).  Animal studies have shown the beneficial effects of whey as well. In rats, when whey protein was ingested along with resistance exercise, its effects promoted higher body weight and muscle weight gain than in rats who exercised alone (7). Even in older aged men (over 70 years), whey protein stimulated muscle protein accretion more effectively than casein and casein hydrolysate (8).

The timing of whey protein consumption, either pre or post exercise, can have different effects on muscle mass and body composition. In one study, eight subjects were given either a whey protein or carbohydrate supplement twenty minutes before resistance exercise. Results showed that 24 hours post exercise, participants who consumed whey protein had significantly greater increases in resting energy expenditure than those who consumed a carbohydrate supplement (9).  In another study, 23 males consumed a supplement containing 40 g of whey isolate during a ten week resistance exercise program. One group consumed the supplement both immediately before and after resistance exercise and the other group consumed the supplement both before breakfast and before sleep.  Results showed that the group who consumed the whey protein immediately before and after exercise had significantly greater increases in lean body mass, greater decreases in body fat, and greater increases in 1 RM strength (10). These results are consistent with another study in which milk protein ingested within five minutes post-exercise showed greater muscle hypertrophy than those consuming it two hours post-exercise (11). Furthermore, from the results of various studies whey protein should be ingested as close to a bout of exercise as possible in order to reap the most beneficial effects on the muscle.

In conclusion, there is ample evidence to support the popularity for the ingestion of the ergogenic aid, whey protein.  Supplementation of whey protein has shown to promote greater muscle hypertrophy and increase muscle mass during a resistance training program. Also, the timing of ingestion of whey protein, either before or after, should be as close to a bout of exercise as possible to produce the best effects.

Whey Protein Shake Ideas

Consuming whey protein doesn’t have to be bland and tasteless.  There are hundreds of recipes and ideas to incorporate whey protein into shakes, drinks, and smoothies.  Here are a few recipes I found that sounded really tasty! You can find more recipes at www.bodybuilding.com.

Wild Berry Boost Shake

   1-2 scoops vanilla whey protein.

8 raspberries

4 strawberries

15 blueberries

16 oz nonfat milk

1/2 cup ice cubes

Peanut Butter And Banana Shake

  2 scoops protein powder

100g almond flakes

1 tbsp peanut butter

500ml skim milk

Half banana

Strawberry Yogurt Smoothie

1 scoop Vanilla Whey Protein
4 large ripe strawberries
3/4 cup milk
1/2 cup plain yogurt
3-4 ice cubes

How Safe Is Whey Protein?

The U.S. FDA does not regulate herbs and supplements, and thus there are no safety “guarantees”.  However, if taken properly and in the right dosages, whey protein is considered safe for the general population.   Prolonged and excessive whey protein use can cause kidney damage.  Whey protein tends to lower blood glucose levels and individuals who are diabetic should take caution.  It can also lower blood pressure and increase the risk of excessive bleeding (13).  Some other common complaints are gastrointestinal issues such as gas, bloating, and cramps.

References

1. Paul GL. The Rationale for Consuming Protein Blends in Sports Nutrition. J Am Coll Nutr. 2009;24:464S-472S. http://search.ebscohost.com/login.aspx?direct=true&db=s3h&AN=49785134&site=ehost-live.

2. Hulmi JJ, Lockwood CM, Stout JR. Effect of protein/essential amino acids and resistance training on skeletal muscle hypertrophy: A case for whey protein. Nutrition & Metabolism. 2010;7:51-61. http://search.ebscohost.com/login.aspx?direct=true&db=a9h&AN=52859182&site=ehost-live. doi: 10.1186/1743-7075-7-51.

3. Whey Protein. Alternative Medicine Review. 2008;13(4):341-347. http://search.ebscohost.com/login.aspx direct=true&db=a9h&AN=36459242&site=ehost-live.

4. Kerksick CM, Rasmussen CJ, Lancaster SL, et al. The Effects of Protein and Amino Acid Supplementation on Performance and Training Adaptations during Ten Weeks of Resistance Training. Journal of Strength & Conditioning Research (Allen Press Publishing Services Inc ). 2006;20(3):643-653. http://search.ebscohost.com/login.aspx?direct=true&db=s3h&AN=22681341&site=ehost-live.

5. Andersen LL, Tufekovic G, Zebis MK, Crameri RM, Verlaan G, Kjaer M, Suetta C, Magnusson P, Aagaard P. The effect of resistance training combined with timed ingestion of protein on muscle fiber size and muscle strength. Metabolism. 2005; 54(2):151-6.

6. Tang JE, Moore DR, Kujbida GW, Tarnopolsky MA, Phillips SM. Ingestion of whey hydrolysate, casein, or soy protein isolate: effects on mixed muscle protein synthesis at rest and following resistance exercise in young men. J Appl Physiol. 2009;107(3):987-992. http://search.ebscohost.com/login.aspx?direct=true&db=s3h&AN=44180926&site=ehost-live.

7. Haraguchi FK, Silva ME, Neves LX, dos Santos RC, Pedrosa ML. Whey protein precludes lipid and protein oxidation and improves body weight gain in resistance-exercised rats. Eur J Nutr. 2011; 50(5):331-9.

8. Pennings B, Boirie Y, Senden J, Mg, Gijsen A, P., Kuipers H, Jc. Whey protein stimulates postprandial muscle protein accretion more effectively than do casein and casein hydrolysate in older men. Am J Clin Nutr. 2011;93(5):997-1005. http://search.ebscohost.com/login.aspx?direct=true&db=c8h&AN=2011049478&site=ehost-live.

9. Hackney KJ, Bruenger AJ, Lemmer JT. Timing protein intake increases energy expenditure 24 h after resistance training. Med Sci Sports Exerc. 2010;42(5):998-1003. doi: 10.1249/MSS.0b013e3181c12976.

10. Cribb PJ, Hayes A. Effects of supplement timing and resistance exercise on skeletal muscle hypertrophy. Med Sci Sports Exerc. 2006; 38(11):1918-25.

11. Esmarck B, Andersen JL, Olsen S, Richter EA, Mizuno M, Kjaer M. Timing of postexercise protein intake is important for muscle hypertrophy with resistance training in elderly humans. J Physiology. 2001; 15;535(Pt 1):301-11.

12. Sports Nutrition: A Practice Manual for Professionals 4th ed. 2006, Marie Dunford.

13.  http://www.mayoclinic.com/health/whey-protein/NS_patient-wheyprotein/DSECTION=safety