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Walk into any gym or health food store and you'll see protein supplements for sale. There are many different kinds, like casein and whey, promising to help you burn fat or gain muscle. What they all have in common is a little note on the label that reads, "These statements have not been evaluated by the Food and Drug Administration.” That’s because they probably won't help you burn fat or gain muscle.
Fast fact: 1.2% of your muscle are replaced every day. That means you get a completely new set about every 3 months.Lots of people believe the advertising because they see improvement while they’re taking the protein powder. And when you plonk down fifty bucks for a drink powder, you're likely to do everything possible to make it work, like sticking to an exercise routine and eating better. You’ll see positive results and figure the protein supplement must be helping. Muscles are made of protein, so if you eat more protein, it’ll get added to your muscles, right? It only makes sense...
Here's what's really going on: Your body is constantly rebuilding itself, taking apart little pieces—cells and molecules, including proteins—and putting them back together (synthesis). Keeping things in flux like this helps your body react quickly to new circumstances. By changing how quickly it breaks itself down and builds itself back up, your body adapts to a more or less active lifestyle.
After intense exercise, the cycle of breakdown and synthesis in your muscles speeds up. If there are enough amino acids—the things proteins are made of—floating around in your bloodstream, protein synthesis will outpace breakdown for the next day or two, slowly increasing the amount of muscle protein over time.
Fast fact: You have tens of thousands of different types of proteins in your body. Some are very long, like the ones in your hair and muscle fibres. Others, such as digestive enzymes, look more like tiny, crumpled up balls of paper.You get these amino acids by eating foods that have protein in them. Digestion breaks the proteins apart and sends amino acids where they're needed. So it comes down to eating the right amount of protein to meet your body’s needs.
For an average Grade 9 student, 50 grams per day is enough. Yet the average Canadian consumes over 75 grams per day! So just by eating normally, you probably get way more protein than you can use. Of course, not everyone is perfectly average, and having more or less mass to maintain changes the recommendation. A good rule of thumb is about one gram of protein per kilogram of body weight. For almost everyone, that will be plenty.
Consuming extra protein won't help you burn fat or gain muscle because your body doesn't just automatically add whatever you eat to your muscles. Once your body uses all the protein it needs to rebuild itself, the rest of the protein is just broken down and burned off or stored for energy.
So if you really want to get in shape, ignore the advertising for expensive supplements. Worry more about eating enough fruit and vegetables, and keep working out!
Nutrition for Everyone: Protein (US Centers for Disease Control and Prevention)
Canadian Trends in Nutrient Intake from Food Consumption (Alberta Ministry of Agriculture and Rural Development) Dietary Reference Intakes (Health Canada) Dietary Supplement Labeling Guide (US Food and Drug Administration)
Scholarly publications and textbooks
Atherton PJ, Smith K. 2012. Muscle protein synthesis in response to nutrition and exercise. The Journal of Physiology. 590.5:1049–1057. Campbell NA, Reece JB. 2005. Biology. 7th ed. San Francisco: Pearson. Kumar V et al. 2009. Human muscle protein synthesis and breakdown during and after exercise. Journal of Applied Physiology. 106:2026-2039. Nelson DL, Cox MM. 2008. Lehninger Principles of Biochemistry. 5th ed. New York: W. H. Freeman and Company.