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Everything You Need to Know About Your Metabolic Rate

If you've ever tried to lose weight, then you've probably wondered at one time or another about your metabolism, or metabolic rate. Metabolism is the body's biochemical anabolic (creating or synthesizing) and catabolic (breaking down) reactions, and the rate at which one burns calories.  

To figure out your rate of metabolism, everyone starts out with a basal metabolic rate (BMR). This is the number of calories you need to just stay alive in a lying state (no exertion). This is the rate your body burns calories in a rested state and in a room with neutral temperatures, while in a post-absorptive and fasting state. There are formulas to figure out exactly what your unique BMR is, but in general, most normal adults' BMR will require somewhere around 1,200 to 1,800 calories per day.

But don't be scared by this small caloric number.  To find your total energy needs, this number still has to be multiplied by a factor involving energy expenditure and/or illness, giving you your Total Energy Expenditure (TEE) calories, which of course will be a larger number than the BMR calories.

Yes, it's irritating but true:  Some people have higher metabolism and some lower - It's a very personal thing depending on many factors. The good news much of it is modifiable.  Some of these things include:

•    Exercise - Cardio and weight resistance can increase your metabolic rate up to 15 times your basal rate, so getting out the sneakers is one of the best ways to rev up your metabolic rate.

•    Hormones - Several hormones can affect metabolism, especially throxine (T4) and triiodothyronine (T3), which from the thyroid, raise metabolism. Hypothyroidism (lack of thyroxine) can lower metabolism and hyperthyroidism can increase it, and it's important to have enough iodine in the diet to prevent this problem. These thyroid gland hormones major function Is to direct metabolism, body temperature and such.

Other hormones also affect metabolism, such as testosterone, insulin and human growth hormone, which can increase metabolism rates by 5 to 15%. The more recently discovered hormones ghrelin and leptin affect metabolism, with grehlin causing hunger and leptin causing satiety.

•    Nervous system - Stress increases the release of epinephrine and norepinephrine, which also increases metabolic rate.

•    Age - Children and teens have higher rates of metabolism due to the massive growth they are undergoing. Older folks have lower BMR as they lose more muscle mass with age and bodily processes slow down.

•    Food - That plate of food you just ate actually temporarily increases metabolism, by about 10-20% with something called thermogenesis.  Different foods can increase it at different rates. High fiber and high protein foods can increase metabolism more than highly processed carbohydrates and fats.  Grapefruit fibers and antioxidants are known to increase metabolism, as are the catechins from green tea.

•    Temperature - When your body is hot, metabolism increases, such as when you have a fever, or when you are very cold and the body is trying to heat up to compensate.

•    Other factors such as pregnancy and inherited disorders can affect metabolism. Pregnancy increases metabolism, as does having a fever, cancer or other illness such as an infection. Fasting can slow metabolism because as body weight decreases, there is less body mass burning energy. And muscle is much more metabolically active than fat, another reason to hit the gym!

To find out in what shape your metabolism is, it's important to look at your overall lifestyle and situation and keep these many factors in mind. You can definitely increase your metabolism, if you take the steps needed to do so.

Catherine S. Hains, MS RD earned a Bachelor's Degree in Broadcast Journalism from Texas Christian University where she reported and wrote for the Fort Worth Star-Telegram for 12 years. Her lifelong  interest in nutrition and wellness continued to nag at her, however; and after starting a family, she went on to earn her Master's Degree in Nutrition from Eastern Michigan University. Catherine, now a Registered Dietitian, is the owner of Lighthouse Nutrition and Wellness in Gig Harbor, WA.  Her favorite areas include helping people lose weight, analyzing fad diet claims, easy and healthy food preparation, healthy lifestyles, teaching children nutrition, and keeping up with clinical findings. For more information on Catherine, visit www.lighthousenutrition.com or write to Catherine at info@lighthouse-nutrition.com.

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