Metabolism explained: what is it and how it works
Nowadays we are often bombarded with the word ‘metabolism’. We keep
hearing, reading and using the word metabolism as if it were some
sort of magic word! But what is metabolism? Well, in very simple
terms, metabolism is the rate at which the body burns up energy.
Metabolism varies from person to person and can be slower of faster
compared to a person of similar body size.
Basal Metabolic Rate (BMR)
order to compare one person's metabolism with another's, scientists
have devised a new buzz word - basal metabolic rate (BMR).
BMR is the rate at which the body uses up energy when at rest - e.g.
when sleeping or just lying in bed.
more a person weighs the higher BMR will be. The metabolic rate of
very heavy women is about 25% higher than that of thin women.
BMR is much greater in childhood than in adulthood. After
the age of about 20, it drops about 2 per cent, per decade.
People whose bodies contain a higher proportion of muscle
to fat, tend to have a higher BMR than those with lower muscular
proportions - all other things being equal.
very rough guide, the average person's BMR is about half a calorie
per pound of body weight, per hour. So, if you weigh 140 pounds you
will use up approximately 70 calories an hour or 1680 calories per
day doing nothing.
5 important things to know
higher your BMR, the easier it is to lose weight
other things being equal, the more energy your body needs in order
to tick over, the more food you can eat without gaining weight - or
conversely, the less reduction in food you need to make in order to
lose weight. Thus a high BMR tends to make dieting and weight loss
BMR decreases when you go on a diet which has fewer calories than
your normal diet
response to fewer calories, the body lowers its BMR because it
thinks there is a famine. It therefore 'slows down' in order to
conserve energy. This means that when you eat less, your body will
try to store more in order to ensure ‘survival’. Therefore, if you
go on a diet, it is important that you are sensible about it and
don’t suddenly restrict drastically your intake of calories.
(3) Your BMR increases in response to increased physical
only do we use up calories doing exercise but the increased BMR
continues even after we have done our exercise, often for several
hours. The amount of increase varies from person to person but even
a modest increase should counteract the body's tendency to decrease
BMR when we cut calories.
Exercise is the ONLY effective way to increase your BMR
diets claim to increase metabolic rate through special fat-burning
exercises or fat-burning foods. The truth is, your metabolic rate
falls if you start dieting and start to shed excess pounds. You may
be able to reduce the extent of the fall by increased exercise but
there is no evidence whatsoever that your metabolic rate will be
higher than it was before you dieted.
Obesity is not caused by a slow BMR
Except in the rare
cases of serious metabolic illness it is not possible to blame your
metabolism for obesity. Your metabolism certainly has an effect on
how much you weigh but the main reasons lie elsewhere. So don’t make
up excuses, start exercising (half an hour walk everyday qualifies
as exercise) and stop eating junk food!