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Metabolic rate

A company called healthetech have just (2001/12) released a device called the BodyGem, which is a handheld device capable of measuring the basal (resting) metabolic rate (RMR) in a ten minute test, rather than taking hours or days in a sealed respiratory chamber with continual gas testing.

It works using the sneaky technique of knowing that everyone breathes in 20.8 percent oxygen, and that over time, you will breath out unused oxygen according to your metabolic rate, so it measures the difference in oxygen over time in the breath.

This means that it is now definately possible to test and find out if your basal metabolic rate is being affected, and use this to improve your health.

Your metabolic rate can be influenced by a number of factors, some of which you can control. These include:

• Gender: Due to their larger size and greater muscle mass, men's rates are 25 to 30 percent higher than women's.
• Race: Black people have a slower metabolism than white people.
• Size: Heavy people have higher metabolic rates.
• Age: Young people burn calories faster. The RMR in girls (15 to 18) peaks earlier than in boys (18 to 21). It then drops by about 3 percent per year.
• Physical Condition: fit people have a faster metabolism due to their leaner body composition. 1 pound of muscle burns 6 times as much energy as 1 pound of fat.
• Conscious State: Metabolic rate slows down when you sleep and rises when you wake up.
• Stimulants: Metabolic rate rises temporarily with caffeine and nicotine, which raise the heartbeat, and also with alcohol, which causes internal temperature changes that have an impact on RMR.
• Hormones: Some surveys have found that metabolism dips just before ovulation, and at menstruation, then it starts to rise when the body temperature climbs. Menopause causes the metabolism to slow down.
• Climate: As the weather gets warmer, RMR drops slightly as less energy is expended on keeping warm.

You can do stuff which will affect your metabolic rate. These things include:

• Have breakfast: A substantial protein-rich breakfast can boost RMR. A big meal at night, followed by bed will not be burned, and is thus stored as fat.
• Get active: Your metabolic rate rises during aerobic exercise and for up to an hour afterwards.
• Train seriously: A long term commitment to training can convert fat into muscle, so much so, that if you have been sedantary in your lifestyle, you could see improvements of up to 10 percent per year.
• Diet: Only diet if you are overweight, don't try and lose more than 2 pounds per week, and don't try and lose more than 5 percent of your body weight per session. If you do, your body will react to being starved, and change your metabolism to cope, thus negating your efforts at dieting.

Your RMR is the single biggest component in the amount of calories that you use every day. If you are an exercise nut, it can be 60 percent of all the calories that you use in a day, but if you are a couch potato, that rises to 80 percent of daily calorie expenditure.

last modified 00:45 2003/08/14