Just exactly what is metabolism? And how does it influence your ability to manage your weight? If you’re not sure, you are not alone. The word metabolism is often misunderstood and misused. On the other hand, if you’ve ever thought “it must be my metabolism” keeping me from losing weight. You may be right and then again you may not.
Metabolism is complex. It involves more than simply burning calories. You might think of it as the way in which your body gets the energy it needs to function from the food you eat. You need energy to keep your heart beating, lungs breathing, and nerves firing even when you are at rest. However, it also involves the processes by which your body fuels all of the chemical reactions needed to build, maintain, breakdown, and repair body tissues.
The speed with which your body performs these functions is often referred to as metabolic rate.
What Makes Your Metabolism Unique?
Your metabolism is influenced by such things as your body composition and weight, gender, age, height, thyroid, and activity level. What you eat can also influence your metabolism. But the effect of food and other supplements is very small.
Body Composition and Weight
The rate or speed with which you burn calories when you are AT REST is primarily influenced by your body composition. The more fat-free mass you have relative to your total body weight the higher your metabolic rate. Fat free mass is commonly referred to as lean body mass or LBM. It includes tissue such as lean muscle, bones, and organs.
The activity of lean body mass is much greater than that of fat tissue. Men typically have significantly more muscle mass than women. This is why the average man has a higher metabolic rate than the average woman by as much as 10 to 20 percent.
Although lean body mass may be the primary determinant of metabolic rate for individuals with a healthy body weight, it is a different and more complicated story for those who are significantly overweight.
The greater a person’s weight the harder the body must work to support tissue of all kinds, both fat and fat-free. A plus-sized woman could have a metabolic rate as much as 50 percent higher than a thin woman!
Height
As with weight, height influences body size. The taller you are the greater the distance that must be covered to provide your body with the energy and nutrients it needs. This increases metabolic rate.
Gender
As mentioned previously in the discussion on body composition, men usually have more muscle mass than women. This gives men a faster or higher metabolic rate.
Temperature
The colder or hotter the environment, the harder your body must work to regulate body temperature. This will raise metabolic rate. However, given that many people today live in temperature controlled environments, the effect of temperature on metabolism is minimal.
Age
The older a person’s age, the slower the metabolism. There are many reasons for this. There tends to be a loss in muscle tissue in part from the aging process itself and in part from a decrease in level of activity. Exercise can slow down but not stop this natural process.
Thyroid
The thyroid is a small gland that lies just below the skin under the Adam’s apple in the neck. The thyroid secretes hormones that influence metabolic rate (speed of metabolism).
Certain medical conditions and medications can influence the functioning of the thyroid gland. If the thyroid is over stimulated it will speed up metabolism. If it is under stimulated, metabolism is slowed down.
Heredity
Some people are born with a metabolic rate that is faster than the average. For these individuals, eating enough food to avoid being too thin may be challenging. Other people with an inborn tendency for a slower metabolism struggle to avoid weight gain.
Most people fall within the range of average.
Activity Level
You have no control over your height, gender, age, or heredity. The functioning of your thyroid gland, on the other hand, needs to be checked and, if necessary, managed with the assistance of your medical doctor. The one thing YOU CAN DO to positively impact your metabolism for weight loss is to engage in increased physical activity or exercise.
If you’ve thought, it must be my metabolism, how do you feel now? Still convinced?
I’ll cover how metabolic rate is determined and the ways in which increased physical activity or exercise can positively impact metabolism in parts two and three of this series.
Till next time, watch your calorie intake, eat healthy food, and be active!
Update: The other articles in the series on metabolism are now complete:
{ 3 comments… read them below or add one }
I am surprised that you did not mention how certain medicines can also affect metabolism. Many people do not realize how their medication can be working against their weight loss or weight management goals. Some medications for some people cannot be avoided of course, but in my case I was put on an anti-depressant that frequently causes weight gain and after gaining 40 pounds my doctor is switching me to another anti-depressant. If I would have known up front about the high possibility of weight gain, I would have asked to try a different anti-depressant from the beginning. It’s extremely frustrating to gain so much weight so quickly. I never had a weight problem before going on this particular anti-depressant.
Thanks.
Antidepressant statistics
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http://www.cdc.gov/nchs/pressroom/04news/hus04.htm
Almost Half of Americans Use at Least One Prescription Drug Annual Report on Nation’s Health Shows
For Immediate Release
Thursday, December 2, 2004
Contact: CDC National Center for Health Statistics Press Office (301) 458-4800
E-mail: paoquery@cdc.gov
Health, United States, 2004, With Chartbook on Trends in the Health of Americans. 513 pp. (PHS) 2004-1232. GPO stock number is 017-022-01575-7. This report may be purchased from the Government Printing Office
Health, United States, 2004, Homepage
The Nation’s medicine cabinets are more crowded than ever, with almost half of all people taking at least one prescription medicine and one in six taking three or more medications, according to the U.S. Department of Health and Human Services’ (HHS) annual check-up on Americans’ health.
Hi Janet,
Yes, I absolutely agree. Medications can and often DO influence metabolism. I mention that in this article under the section on the thyroid gland.
“Certain medical conditions and medications can influence the functioning of the thyroid gland. If the thyroid is over stimulated it will speed up metabolism. If it is under stimulated, metabolism is slowed down.”
Your experience is all too common I’m afraid. Although medications are important and necessary in certain situations, I believe they tend to be over-prescribed. That’s why I am so passionate about teaching the merits of healthy eating and healthy living. Thanks for sharing the stats!
Lori
Thank you VOICE OF REASON! So many diet pills and powder websites completely misuse the word metabolism.They all seem to think it’s a muscle or something,it’s become such a diet industry buzzword because it sounds scientific but all it really means is “breakdown”. It’s great to see blogs like this telling people the truth about how our bodies work.
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