Author: Dariella Gonitzke, MS, RD
Protein supplements are popular among trained athletes, especially bodybuilders and strength athletes. These supplements are marketed as powders, premixed drinks, and bars. Along with resistance training and adequate calories, proteins from either food or supplement sources can contribute to increasing skeletal muscle. Protein supplements are neither more nor less effective than food proteins for muscle growth.
The purity of dietary supplements has become a critical issue for athletes as some supplements may be tainted with substances banned by their sports governing body. To avoid this, many athletes choose to obtain protein from food source alone. Using a combination of food sources and supplement sources is the most common method since supplements offer the convenience of portability and preparation (e.g. adding protein powder to water can be done quickly anywhere). Keep in mind that supplements are chosen for convenience, not because adequate protein cannot be obtained from food alone.
Protein Supplement Ingredients
Protein supplements typically contain whey, casein, egg and soy proteins. Whey is the most common ingredient in many protein supplements. Whey and casein are both processed from milk, and whey is further processed into whey protein isolate, whey protein concentrate or whey powder. Whey concentrate and whey powder contain lactose. Whey protein isolate is a more concentrated source and both carbohydrate (lactose) and fat are removed. The end product is high in essential amino acids, especially the branched-chain amino acids (leucine, isoleucine, and valine).
When shopping for a whey protein powder always read the ingredients list to know which type of whey is provided. Isolate refers to the purest form and has the most protein (90%), while concentrate contains less protein (80%) and is typically cheaper.
Casein, which often appears as caseinate on a label, has a different amino acids composition and is particularly high in glutamine. Egg white protein (albumin) refers to dried, pasteurized egg whites.
Protein powders may contain only protein but most also contain carbohydrate to make them more palatable and to provide some post-exercise carbohydrate.
Types of Protein: Slow versus Fast
Protein consumed should always be of high quality. High quality proteins include egg white, whey, casein, and soy. Although these proteins contain about the same amount of essential amino acids, they are digested and absorbed differently.
Whey and soy are known as “fast” proteins and are rapidly digested so blood amino acid concentration quickly increases but remains elevated for only a relatively short period of time. In contrast, ingestion of casein, a “slow” protein, results in slower but more sustained rise in blood amino acids.
A combination of rapidly and slowly absorbed protein at each meal or snack may be the best approach because “slow” proteins inhibit skeletal muscle breakdown whereas “fast” proteins increase protein synthesis. Milk is a combination of both “slow” (casein) and “fast” (whey) proteins. The ingestion of milk after resistance exercise appears to promote skeletal muscle growth faster and to a greater extent in the short term compared to soy. Many protein supplements contain both whey and casein to take advantage of their different absorption rates.
How much Protein do I Need?
The Academy of Nutrition and Dietetics and the American College of Sports Medicine recommend 1.2-1.7 grams of protein per kilogram (kg) of bodyweight per day with the higher end of the range recommended for people trying to increase skeletal muscle. For example, a 130 pound female would need a range of 71-100 grams of protein per day. However, many athletes consume much more than recommended and some bodybuilders have an intake of up to 3-3.5 grams/kg/day. This is far more than the body can safely handle!
The maximum amount of protein that the body can safely handle is 2.5 grams per kilogram per day. Why is this the maximum? Normal protein metabolism requires that amino acids (the building blocks of protein) to be broken down in the liver. As part of this process, ammonia is produced. Ammonia is toxic to the body and must be converted to urea for excretion in the urine. All humans have a maximum rate of urea synthesis, which is well above that needed to metabolize the amount of protein normally contained in the diet. When protein intake surpasses 2.5 grams/kg/day there is a danger that the individual’s maximum rate of urea synthesis will be exceeded, which can lead to elevated blood ammonia levels, a dangerous medical condition. In addition, there is no scientific evidence that such a high intake is more effective for increasing skeletal muscle size. Studies have shown that there is a ceiling for protein intake and muscle building.
How much Protein do I Consume per Meal?
Many people wonder what the maximum amount of protein that the body can absorb at each meal. A common belief among strength athletes is 30-50 grams per meal which has resulted in diet plans that include multiple meals or snacks throughout the day, each with an excessive amount of protein.
Scientific evidence suggests that this rationale is incorrect. In general, the absorption of amino acids from protein is slow, about 5-8 grams per hour. Whey protein isolate has the highest rate of absorption, about 8-10 grams per hour. If you eat every 2 hours you need to consume 10-16 grams of protein per feed or 16-20 grams of whey protein isolate per feed. Taking more protein than this results in the amino acids being oxidized (burned for energy) because the skeletal muscle cannot use the excess protein.
Timing of Protein Intake
Eating every 2-3 hours helps to increase lean body mass while having protein several times during the day may enhance available amino acids during workouts. Going into strength workouts nourished may enhance strength gains and decrease net protein losses. Eat about 10 grams of high quality protein plus a simple carbohydrate before workouts.
Recovery nutrition after a workout is crucial. The short-term effect of exercise is to put the body into a catabolic “breaking down” state of certain tissues to provide energy. This catabolic or “breaking down” state is followed by an anabolic or “building” state that allows for recovery and muscle growth. Refueling immediately after workouts during that “anabolic window” 1-2 hours after exercise and will enhance strength gains. Aim to consume 10-20 grams of high quality protein along with a complex carbohydrate immediately after exercise, but no later than 2 hours after exercise.
There are 10 grams of protein in:
o 1.5 oz meat, fish or poultry
o 3 oz of tofu
o 2 eggs
o 1 cup of milk or 1.5 cup of soy milk
o 2/3 cup of beans
o ˝ cup nuts
o 2 Tbsp peanut butter
Concerns of a High Protein Diet
Protein supplements make it too easy to consume high amounts of protein which can often be excessive. The practical concerns with excessive protein are dehydration, low carbohydrate intake and excessive calorie intake.
Dehydration can occur because additional water is needed to metabolize protein. Extra water is also needed to flush out urea, one of the by-products of protein metabolism.
Consuming large amounts of protein may come at the expense of limited carbohydrate foods. If protein replaces adequate carbohydrate intake, this could result in lower muscle glycogen (sugar) stores after several days of training. If protein consistently exceeds usual intake, then caloric intake may be too high and body fat may increase over time. Maintaining a balance of carbohydrates, protein and fat along with calories is important.
In summary, for maximum amino acid availability, aim to consume balanced meals and snacks that contain 10-20 grams of high quality protein every 2-3 hours. Choose protein supplements that contain whey isolate and casein for best results and remember to fuel with a protein/carbohydrate mix immediately after workouts for recovery nutrition. Drink plenty of water throughout the day and remember to enjoy your workout and your food!
Dariella offers a variety of nutrition counseling services. Visit her site eatfreelynutrition.com for information regarding how to lose weight fast.
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About the Author
Dariella became a Registered Dietitian after receiving her Bachelors in Dietetics and Masters in Nutritional Science from California State University, Long Beach.
She is a member of the Academy of Nutrition and Dietetics, and has served as President for the California Dietetic Association, Orange District Region. Dariella was awarded "Recognized Young Dietitian of the Year" in California by the Academy of Nutrition and Dietetics for 2010.