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Protein Supplements

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Reviewed for medical accuracy by:

Added to knowledge base:

Jackie Munch

Virginia Uhley, Ph.D., R.D.,


UM Medical School

Dept. of Integrative Medicine





When asked what she thinks of protein supplements, Dr. Virginia E. Uhley, Ph.D., R.D., in the Department of Integrative Medicine at the University of Michigan, says, “It depends on what you’re trying to accomplish.”  With the Atkins diet peaking in popularity, protein seems to be the only “good guy” left of the dietary macronutrients (proteins, fats, and carbohydrates).  Protein powders and bars have also been advertised for years by bodybuilders and trainers as a great way to build muscle.  It is easy, however, to misconstrue the advertising.  In general, more protein does NOT equal more weight loss, and more protein does NOT equal more muscle!  Despite the changes in fad diets, the fundamental principle for weight gain and loss has not changed: to gain weight, eat more calories than you burn; to lose weight, eat fewer calories than you burn.  So if your goal is to lose weight, eating more protein may be counterproductive.  Adding a protein supplement to your diet adds calories (3-4 Cal/g of protein), and your body uses these calories in three ways:  First, it lays down glycogen, the quick energy source for cells, in the form of carbohydrates.  Second, it builds muscle, using protein.  Finally, it stores whatever is leftover as adipose tissue, or fat.  The bad news?  The body has “set points” for the amounts of glycogen and muscle it stores, but (as many of us are painfully aware), the body’s capacity for storing fat is infinite!  The good news is that, by exercising regularly, we can gradually train our bodies to burn more of these calories, and, to an extent, build more muscle. 

Just how much protein do you need?  The dietary guidelines vary with age and activity level, and some general categories are below (1 kg = 2.2 lb).  Information was gathered courtesy of Dr. Mary Ann Nirdlinger, MD, MPH.

Infants (6 months) need 2.2 g/kg bodyweight/day of protein

Age 6 months – 1 year: 1.6 g/kg/day

By 7 years old: 1.0 g/kg/day

Adult men (19) and women (15): 0.8 g/kg/day

Pregnancy: add 10 g/day


            First 6 months: add 15 g/day

            After 6 months: add 12 g/day

Some measures of macronutrient requirement use percentages based on a 2400 cal/day diet, and the current American Dietary Guidelines are for 55% of dietary calories to come from carbohydrates (no more than 10% sugars), 15% to come from protein, and 30% or less to come from fat.  The proportion of daily protein intake also changes with age:

            Infancy: 40%

            Children: 35%

            Adults: 15-20%

Elite athletes and people who are fighting an acute illness need more daily protein than normal to replace what they burn (1 g/kg/day or more). 

According to Dr. Nirdlinger, most people in the United States are not protein deficient.  So why would someone need a protein supplement?  If you’ve calculated your daily requirement and determined that you are not meeting that need, you might be a candidate.  Many people choose a protein supplement because they are unable or unwilling to eat the amount of eggs, meats, or other food sources needed to achieve their daily protein requirement.  This includes vegetarians or people on very low-fat or calorie-restricted diets.  On the other hand, others might choose a protein supplement because they are trying to overcome a very high metabolism and gain weight without taking in too much fat or cholesterol.  Basically, a protein supplement is a legitimate option for people whose bodies will burn the protein.    

So you’ve decided to take a protein supplement.  With all of the different products out there, which one do you choose?  Dr. Uhley recommends protein powders over protein bars, because bars often contain extra unwanted ingredients.  Dr. Uhley also points out that any protein supplement should contain all nine essential amino acids: histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine.  Essential amino acids are those protein molecules that our bodies cannot synthesize, so they must be obtained in our diets.  Once you’ve established that a supplement meets these requirements, there are three basic types of protein powders from which to choose: egg, soy, and whey.  Most have comparable amounts of protein per scoop (usually about 20-24 g), so you will probably base your decision on other factors.  Take a look at your powder’s nutrition information to see what else you are eating along with the protein.  Many powders contain some amount of fat and carbohydrates, and perhaps some cholesterol.  Whey powders are derived from milk, and are not a good choice for people who are lactose intolerant.  Egg powders are derived from egg whites (note: if you want to save some money, and are willing to add some egg whites to your diet, it’s the same thing!), and soy powders are derived from soy beans.  For those consumers at risk for cholesterol problems or heart disease, soy might be the powder of choice: in 1999, after a review of human studies indicating the effects of soy protein on cholesterol levels, the FDA approved the claim on food labels that “a daily diet containing 25 g of soy protein, also low in saturated fat and cholesterol, may reduce the risk of heart disease.” (Read the article at http://www.cfsan.fda.gov/~dms/fdsoypr.html)  As always, consult your physician about your individual dietary requirements and risks, and happy hunting!


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