The basic principles of weight loss
is not rocket science so if
you've got an interest in losing some weight, here are a few things you ought to
know about first.
The picture on the left shows Sarah before she started eating
sensibly and exercising.
The picture on the right shows Sarah after she joined Dudley
Ladies.
Calories
Calories measure the energy content of the
food you eat. You use energy - that is, burn calories - just by being alive.
If you exercise, you use more energy than if you are sedentary.
If the
total energy you consume in a day exceeds the energy that you use up, then the
surplus is stored by your body, usually as fat.
So broadly
speaking, there are two ways to reduce the amount of fat in your body:
·
Eat fewer calories by eating less or differently; and/or
·
Burn more calories by exercising more. 
Provided
you achieve either or both of these, you will reduce your body fat.
To find out
the amount of calories you need each day, either see Phil and have your Body
Fat/Daily Calorie Intake taken on the clubs BIA Body Fat Monitor Scales or else
estimate it yourself by first multiplying your weight in kilograms by 33 to
estimate your daily calorie requirement for a moderately active person who does
not exercise.
So if you
weigh 75kg, are moderately active but do not exercise, you need about 2475
calories a day.
Then add
100 calories for every mile you walk, jog or run. So if you weigh 75kg and run
5 miles a day, you have a calorie requirement of (75 x 33) + (100 x 5) = 2975 calories a day.
If you want
to lose weight, reduce your calorie intake to less than your daily calorie
requirement. You should not reduce your calorie intake to less than 80% of your
calorie requirement.
If your
weight is broadly constant at 75kg and you take no particular exercise, then you
are probably consuming about 2475 calories a day. Suppose you start running 5
miles a day. Your calories consumption will go up by 500 calories a day - or
possibly a little more to take account of the increased metabolic rate. Fat
weighs in at 1/9g per calorie. So this calorie deficit should reduce your fat
level by 55-60g per day, or 0.4kg a week.
How weight loss programmes work
Weight loss
programmes are only effective if they reduce the calories you consume or
increase the energy you burn. They might work by:
·
changing the calorie content of a given volume of food, by
encouraging you to eat less fat (which is 9 calories per gramme) and more
carbohydrate and protein (4 calories per gramme) or water (0 calories)
·
making it difficult for you to eat so much, by forcing you
to combine foods in particular ways, or by forcing you to eat unappetising or
repetitive things
·
provoking your body into feeling satisfied, for example by
getting you to fill up on dietary fibre, which is bulky; eating often, and so
making sure you don't feel hungry; and ensuring that your blood sugar levels do
not swing around too much by encouraging you not too eat foods which promote an
insulin response
·
encouraging you to eat at times which increase your metabolic
rate and so increase your energy consumption. For example, it might be that
your metabolic rate is higher if you eat more often, or if you eat during the
day rather than in the evening.
Such weight
loss programmes may have value, but only if they help you to achieve the
underlying basic requirement of eating fewer calories or burning more energy.
Many diets are not sustainable, particularly if they work by artificially
limiting what you eat.
Diets that
cause weight loss by reducing your water content are certainly not going to be
sustainable and may make you ill.
Do you want to lose weight or reduce your body fat?
Consider
for a moment what it is you actually want to achieve. Does it really matter to
you how much you weigh? Or is this a proxy for other concerns you have about
yourself: for example about how your body looks, how toned your muscles are, or
how fit you are? It is important to decide what you really want to achieve.
The reason
this matters is that lean muscle tissue is heavier than fat. So if you
exercise, you may reduce your fat stores but develop more lean muscle tissue, so
that your weight may actually increase (or fall more slowly). Over time, you
may look more toned and fit, and carry less fat, but weigh much the same as
before.
Most people
who say they want to lose weight really want to reduce their body fat. Unless
there is some reason why you want to weigh less, you should focus on reducing
body fat.
Exercise and dieting
It is a bad
idea to increase your exercise and go on a diet at the same time. When you are
a runner, you need more energy and nutrients, and you are much more likely to
get ill or injured if you try to restrict what you eat at the same time.
Running
helps you to lose body fat in three ways:
·
you will burn more energy while you are running- about 100
calories for every mile you jog or run
·
you will raise your basic metabolic rate, so that you burn more
energy even when you are not exercising. (This effect is most pronounced if you
run at least 4 times a week for at least half an hour).
·
you will increase your quantity of lean muscle tissue, which burns
more calories.
Dieting
will reduce your fat, muscles and water content, whereas running will reduce
your fat but increase the quantity of lean muscle. In addition, running will
improve the tone of your muscles, which will contribute to an improved
appearance. Dieting is often difficult to sustain, because it requires you
constantly to deny yourself what you want. Sometimes, the constraints imposed
by diets are unhealthy, preventing you from eating a good variety of foods.
Running in the "fat burning zone"
Your body
has a number of sources for energy, including glycogen (which is stored in your
muscles and round your liver), protein and fat. Fat is an efficient way to
store energy, but it can only be translated back into energy fairly slowly.
When you
run at high levels of exertion, your body needs a lot of energy quickly, and
uses glycogen, which is the most accessible source of energy. Only a modest
proportion of the energy comes directly from fats. When you run more slowly,
your body does not need to call on the most accessible energy stores, and a
higher proportion of the energy you use comes from fat. This is why some
aerobic equipment in gyms, and some books about exercise, talk about fat burning
zones.
So it
sounds as if you must run more slowly to burn more fat, right? Wrong.
This
argument is wrong on two counts. First, you will almost certainly burn less fat
overall if you run slowly, even if it represents a higher proportion of the
energy you use. If you have an hour to exercise, the further you run the more
fat you will burn. Second, what matters for your fat levels is the amount of
energy you consume and the amount of energy you burn: not where the energy comes
from when you exercise. Body fat used during exercise will soon be replaced.
So the
best way to burn fat is to run as far as you can in the time available.
