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I want you to read the title of this post, and then read it one more time. I cannot stress enough that this is simply an introductory measure to helping you understand metabolism. Too often I have found that people, in general, rely too heavily on one source of information without going the extra distance to verify the authenticity/credibility. I want you to understand that I'm still learning every day, and I have a far way to go before I can consider myself a nutrition guru.

Okay, now let's begin.

What is metabolism? It is "The sum of all the physical and chemical processes by which living organized substance is produced, and maintained (anabolism), and also the transformation by which energy is made available for the uses of the organism (catabolism)" (Cancerweb). What this definition is basically stating is that metabolism is the sum of two metabolic functions: anabolism, and catabolism. Anabolism deals with the building processes that your body goes through, such as, adding muscle, bone, and everything else on your body that grows. For this process to go on, it needs energy and raw nutrients; catabolism is the mechanism by which anabolism is powered. Catabolism deals with the breakdown of the nutrients supplied to/by your body.

Another important nugget of information to retain before we venture forth is the idea of negative feedback. According to Tortora and Derrickson, negative feedback is a process which most organisms on this planet use to keep biochemical homeostasis (pg. 10). That is to say that just as organisms make up an environment, biochemical components within our own bodies make up a microscopic environment of their own. The way it works is that once a bodily process completes a cycle, its output is partially fed back into the system’s input to “decide” at what rate to continue this process, if at all. For example, I’m sure most of us have drunk alcohol before. I’d go as far to say that many of us have probably been black-out, passed-out drunk. While blacking-out depends more on a person’s individual brain chemistry, passing-out is a negative feedback mechanism that keeps you from killing yourself. Here’s how: When you drink alcohol you are increasing your BAC (blood alcohol content), and once you knock back enough drinks, your BAC gets dangerously high. Well, as you’re metabolizing the alcohol your body gets signals that the BAC is dangerously high, so once a threshold is reached, your body shuts off and you pass out. This is to keep you from consuming more drinks, and risking alcohol poisoning or death. That’s the cliff notes version but, it sufficiently demonstrates how your body utilizes the feedback system.

Now back to metabolism. It’s a known fact that metabolism decreases with age. The question is why. In some people it seems like metabolism plummeted as soon as puberty stopped, and for others there may have not been a drastic difference between high school and the golden years. The key to keeping your metabolism going strong is proper dieting and supplementation, routine activity, and abstinence from drugs. You see, during your childhood, and adolescence, your body is working hard to develop your brain and your body to their predefined, genetic limits. That means anytime you eat, those nutrients are being allocated to the various parts of your body that require it. Once puberty stops, however, your skeletal structure remains more or less constant, and your brain has pretty much reached maturity as well. This means that a lot less nutrients are being utilized in your body now and if you continue your same lifestyle (exercise/eating/sleeping habits) you’ll most likely notice weight gain. Why? Well, before you may have been ingesting 2,000 calories a day. From those 2,000 calories, your body was using 1,400 for maintenance, another 300 to build your body up, and 300 for exercise. Now that your body is not growing much, save for exercise induced hypertrophy, you have an excess of 300 calories a day that are not being utilized. That’s a lot of excess caloric intake in one day. Now this excess energy is getting stored away as fat, and glycogen stores (daily energy). You are now gaining weight and your body knows it, so to keep from gaining weight unnecessarily so, it’s going to drop your metabolism by the process of negative feedback. What your body is trying to accomplish is slowed weight gain because if less nutrients are being broken down, and used to build up, that means less is becoming fat. The problem here is that if the same amount of nutrients are being ingested then all that has been accomplished is a slowed metabolism. This cycle will perpetuate itself and that’s how many people lose control of their body.

In the next section we will discuss metabolism as it relates to you, and ways to increase your metabolism.

References

Cancerweb. 2007. 8 November 2008 http://cancerweb.ncl.ac.uk/cgi-bin/omd?metabolism.

Tortora, Gerard J. and Bryan Derrickson. Principles of Anatomy and Physiology. Danvers: Von Hoffmann Press, Inc., 2006.