Metabolism, Weight Loss
and How to Boost Both
Fast metabolism, slow metabolism, phfft...what's the
Actually, it's a pretty big one, as it turns out. Possibly
big enough to stop you from losing weight. Ah! Now you're
Metabolism is a much-talked-about, little-understood
topic among people who are trying to gain control of
their weight. To find out what you need to know about
the big difference your metabolism can make, and what
you can do to change it, read on.
What's your Basal Metabolic Rate?
The standard measurement for metabolism is called the
Basal Metabolic Rate (BMR). This describes the minimum
amount of calories needed to simply keep your body going,
sustaining vital functions such as digestion, breathing
BMR varies a lot between different
individuals. These variations can make the difference
between someone being overweight or of normal weight.
For example, many obese people don’t eat any
more food, and might eat less than non-obese people.
For many obese people, this is the result of an extremely
low level of physical activity. For others, it may
simply mean that the obese person has a more efficient
metabolism that requires fewer calories.
BMR generally accounts for around 1200-1400 calories
per day in females, and 1400-1800 calories in males.
This is the number of calories it takes for you to stay
alive. Many factors affect BMR including:
- Gender: Men
tend to have more lean muscle in their bodies than
women. Lean muscle requires more calories, so men’s
BMR is greater than women’s.
- Age: Because of the
increased activity of cells undergoing division, the
younger the person, the faster their metabolism. There
is therefore a decline in BMR of approximately 2% for
every 10 years after age 30.
- Weight: The
heavier a person is, the higher their energy requirements,
so they need more calories to keep their body functioning
and moving. Their BMR is higher, but that doesn’t
mean their metabolism is faster; a point of confusion
- Height: The taller a person is, the
higher their BMR as they have more body surface area
(skin) exposed to the outer elements, equating to greater
- Environmental temperature: People living
in tropical or very cold climates tend to have BMR's
5 - 20% higher than those living in moderate climates.
- Physical activity: People who are physcially
active generally have a higher BMR than those who are
Increasing your metabolism
The higher your metabolism, the faster you will burn
calories. So the obvious question is - how do you increase
your metabolism? Exercise can make a big difference for
First, it can increase the muscle component of your
Lean Body Mass (LBM). Your LBM is made up of your muscles,
bones, organs such as the liver and heart, and the fat
stored in your heart, lungs, kidneys, intestines, muscles,
nervous system and bone marrow.
The greater the muscle component of your LBM, the higher
your metabolic rate, i.e. more calories are burned. Males
usually have a higher LBM (and therefore a higher metabolic
rate) than females by virtue of their larger muscles.
Some female athletes, however, such as swimmers and shot
putters, may have a higher LBM than a male of equal weight.
You don't need to become muscle-bound to significantly
raise your metabolic rate. Any exercise will tone and
improve your muscle build and, as a result, burn extra
calories and help use fat stores.
Second, exercise has the added advantage of increasing
metabolic rate for up to 24 hours after you've finished
working out, depending on how strenuous the exercise
was. So when you relax in a chair after a brisk walk
you are burning up more calories than the person sitting
beside you who didn't exercise.
Without exercise your metabolism slows down. When you
try to lose weight just by cutting calories, you actually
lose muscle from your LBM as well as body fat. This has
the effect of slowing down your metabolism. But if you
exercise as well, then mainly body fat is lost while
LBM is maintained or, more likely, increased. For this
reason, exercise makes weight control easier.
Crash diets slow your metabolism down
The advertising claims for some diets can be quite dramatic.
Claims of an 8 kg loss in two weeks are common. What
is not told, is that about 6 kg of that weight loss is
fluid and muscle tissue. The overall effect is to dehydrate
the body and reduce muscle tissue, the very tissue that
needs to be maintained and built up. Soon the body takes
steps to regain the lost water and weight begins to rise,
causing frustration and disappointment.
The rapid loss in weight is seen
by the body as a “famine” situation.
In a concerted effort to survive, the body dramatically
reduces its metabolic rate within 24-48 hours after you
start dieting. The reduction in basal metabolic rate
can be as high as 45%. This is exactly the opposite effect
to what you want for long-term weight control.
Repeated bouts of severe calorie
restriction can actually have a drastic long-term effect
on weight loss. The body adapts to these constant periods
of “cyclic fasting” by
slowing down metabolic rate to conserve energy. The result
is that diets become progressively less effective.
Menstrual cycle boosts metabolism!
(But not by much)
In the two weeks before menstruation
begins (i.e. after ovulation) there appears to be a natural
inclination for women to increase their food consumption.
Biologically, this makes good sense as the body is preparing
for a possible pregnancy. One study estimated the increased
food intake to account for an extra 500 calories a
day for the 10 days before menstruation. Chocolate
especially seemed to be craved for at this time - a
potential contributor to weight gain.
Within this same
two weeks, basal metabolic rate increases by about 10%.
However, this increase does not compensate for the extra
500 calories consumed on average! Some control over food
intake is required to prevent weight gain. Women on the
pill may not experience this effect of increased basal
Smoking and metabolism
When someone quits smoking, weight is often gained
even if they don’t alter their diet or their exercise
routines at all. That’s because smoking causes
the body to burn slightly more calories in order to cope
with carbon monoxide and other tobacco toxins. When someone
quits, their metabolism slows down to more normal levels,
which means fewer calories are burned. This can lower
energy needs by as many as 200-500 calories.
This might sound like a good reason to continue or take
up smoking. Not so! It is far healthier to be overweight
than to be a smoker. Weight gains when you quit smoking
can be avoided by sensible eating and daily exercise.
Exercise in particular can be very effective in countering
the drop in metabolic rate.
Reproduced with permission from CalorieKing.com.au. All material copyright CalorieKing.com.au