It is widely assumed that exercise is a key part of controlling one's
weight. However, there are many people who find that exercise alone has
very little impact on their weight while others seem able to exercise
and lose weight easily. What is going on? Well, people all respond
slightly differently to exercise due to age, sex and their genetic
inheritance. However, despite any difficulty in losing weight that you
may have inherited, there are different forms of exercise that will
definitely be able to help you lose weight. The different forms of
exercise all have different effects on weight loss. Below I look at:
- Easy/medium intensity cardiovascular exercise - aerobic.
- Hard, high intensity cardiovascular exercise - anaerobic.
- Weight training and other resistance exercise.
1 Aerobic exercise
What is aerobic exercise?
Aerobic exercise is exercise which most people can sustain for hours if
properly conditioned. Heart rates are typically 55-85% of the maximum
heart rate. You breathe in oxygen through your lungs at a rate which
generally allows you to talk. Your heart then pumps blood containing the
oxygen to your muscle fibres. As your muscle fibres contract to produce
movement, they use up oxygen. The harder and faster you go, the more
oxygen that you need, and as a consequence you breathe faster. As you
increase your effort your muscle fibres burn up more sugars and fats to
produce the energy required to make them contract. The result? You burn
calories faster.
What is fat burning? Fat burning
is a form of aerobic exercise that became popular in the nineties. It
is basically lower intensity aerobic exercise. Heart rates are at
typically 55-65% of the maximum heart rate. Unfortunately it is not the
best way to remove excess fat. You actually burn more fat as you
increase the effort. Although the fat burning zone burns a greater
proportion of fat compared to sugar than high effort zones, the high
effort zones burn both more fat and more sugar. The amount of sugar
burnt increases faster than the amount of fats as you up the effort, and
so you could say you enter a sugar burning zone as you go harder.
However, along with the sugar you will also be burning more fat. There
are many studies that have looked at the weight loss effects of aerobic
exercise. Most show a small positive benefit, but one that is far less
effective than modifying dietary intake. These studies have been mostly
done on sedentary or obese people and involve amounts of exercise
typically of between 2-4 hours per week. The truth is that if you are
not intending to do more than 2-4 hours of aerobic exercise per week,
then you are unlikely to lose much weight as a result, unless you also
significantly modify your diet. However, that is not to say you
shouldn't do it. Most studies also show that physical and psychological
health both benefit significantly from this small amount of exercise
when compared to doing nothing. Larger amounts of more intensive aerobic
exercise are generally more effective at achieving weight loss. The
effects of larger amounts of exercise on people vary. Some are
responders and others non-responders. Non-responders are thought to be
people who reduce their levels of everyday activity when undertaking an
exercise program, in order to compensate. In other words if you are
going to treat yourself with extra food or slump in front of the TV
after introducing a new exercise routine then it may well not have any
effect on your weight. I have many clients who are responders, who eat
more healthily when exercising a lot and who treat themselves when they
are having a break from their hard exercise routines. Needless to say
these clients are prone to developing a small paunch when taking it
easy, but find it easy to lose the weight once they start up their
exercise routines once again.
2 High intensity - anaerobic exercise
Anaerobic
threshold is defined as the point during a graded exercise test at
which lactate in the blood begins to accumulate faster than it can be
got rid of. A fit athlete can maintain an effort at the anaerobic
threshold for about 1 hour as long as the blood lactate does not
continue to rise. If the intensity of exercise continues to increase
from this point, as it would in a graded exercise test, then
acidification occurs. This is due to the accumulation of hydrogen ions
formed when the lactic acid produced in muscle is converted to lactate.
The acidification soon causes a severe muscle fatigue and the intensity
of exercise can no longer be maintained.
What is anaerobic exercise?
Your muscle fibres, and most other cells in your body have two main
routes of making energy. The first is aerobic respiration in which sugar
or fat is burnt with oxygen in the mitochondria to produce the energy.
Think of mitochondria as power stations. The second is anaerobic
respiration, in which sugar is turned into lactic acid without a need
for oxygen to produce energy. This happens in the sarcoplasm of the
muscle cells. Anaerobic exercise occurs when you run low on oxygen. As
you exercise harder your muscle fibres try to get more oxygen into the
mitochondria to burn your fuel faster. As you pass through your
anaerobic threshold (see panel to the left), your body is not providing
enough oxygen for your mitochondria to produce all the energy you need.
Your muscle then increasingly relies on the anaerobic respiration in the
sarcoplasm. So at this point the mitochondrial power stations are
working at close to full capacity and as a result you are breathing
pretty hard. Anaerobic respiration is interesting in that it uses up
sugar 15 times faster than the mitochondria. How could this affect
weight loss? Well this form of respiration is now burning calories 15
times faster than the mitochondrial one. The fact is that as you push
harder beyond the anaerobic threshold you make increasing use of
anaerobic respiration and so burn calories at exponentially increasing
rates. You reach a point at which your breathing is at a maximum. This
is called the VO2max. A fit athlete may be able to maintain this rate of
breathing for a maximum of 10 minutes. Your mitochondria are now
working at full capacity and your anaerobic respiration in the
sarcoplasm is working towards maximum. The anaerobic metabolism is
building up lactic acid, which results in increasing acidosis in the
muscles the longer and harder you go on. The fatigue becomes unbearable
and you soon slow down.
Will I lose weight?
Clearly you can burn calories quickly with intense exercise.
However, you can't maintain high intensity for long and so the total
amount of calories burnt may be less than during a long aerobic workout.
However it is likely that your body will remain working long after the
exercise finishes, as it will need to repair itself from the muscular
trauma that normally accompanies high intensity efforts. Other bodily
systems are stressed as well, and these all need energy to be fully
repaired. Basically anaerobic exercise is a useful weight control tool,
but because of its intense nature it should be used sensibly. It is easy
to over exercise and end up injured, ill or disheartened. It is
important to recover from intense sessions, ideally you become fit
enough to use easier exercise sessions as a recovery between the harder
sessions. This way the metabolism is kept high and calories continue to
be burnt faster than before.
3 Resistance exercise
Resistance exercise leads to more muscle mass and an increased
metabolic rate that burns more calories. This is because muscle tissue
requires more calories at rest than fat containing adipose tissue.
Will I lose weight?
There are a number of studies that show resistance exercise to be
effective at producing weight loss. These exercises also increase the
tone of your body. If you select a good range of exercises including
bodyweight exercises and exercises that challenge your balance and
agility, you should find many benefits that go beyond mere weight loss
and looking good. In particular a stronger more supple body is less
injury prone. As a result, less time is spent injured, and exercise
regimes can be kept up for longer without breaks. Breaks that can
easily lead to unwanted weight gain from excess fat deposited around the
body. Also it is worth remembering that the muscle strength and
flexibility gained from resistance exercise can increase the efficiency
of your movements and open up the possibility of new movements that can
burn yet more calories.
Won't I become too muscular?
If you are female and worried that resistance exercise or exercise
with weights in particular will make you too muscular and male in
appearance then think again. There are many different ways of doing
weights and plenty which build strength, agility and balance without
increasing muscle bulk. Most bodyweight exercises won't bulk you up, nor
will all the balance and agility exercises that you can do. Into the
bargain you will find that weight training will build strength, which
will help you avoid injury. It will also tone up your torso, arms and
legs, reducing flabbiness, cellulite and bingo wings.
In summary
Exercise is highly beneficial to psychological health and physical
health. The confidence and satisfaction gained from keeping an exercise
programme going add to self esteem and very often have a positive impact
on attempts to change diet. As explained above, the exercise itself is
most likely to reduce your weight if you follow as many of the following
points as possible:
- Keep the exercise programme going for at least 3 months or more.
- Build up your exercise programme to at least 5 hours per week.
- Try to incorporate all types of exercise, steady aerobic efforts, short and hard anaerobic efforts and resistance training.
- Don't build up too quickly. If you are getting particularly sore or
tired, ease off a bit with shorter sessions and/or less intense
exercises.
- Keep it enjoyable. This exercise lark only really works when you
enjoy it. So make it an exercise/sport that appeals. If not the chances
of giving up and putting weight back on are high.
Resistance band training, or strength training, is a form of
exercise that stretches and strengthens the body using resistance bands.
By stretching elastic bands instead of free weights or machines for
resistance, a person can strengthen one group or a number of muscle
groups at any one time through a series of high interval resistance band
exercises. The workouts are designed to only last about 30 seconds or
so, doing as many repetitions as you can with the exercise, with the
focus being on high intensity and good form.
How much weight you can lose will depend on several factors. Keep in mind
success shouldn't just be based on how much weight you show on the
scales. Muscle tissue is more dense then fat, so although you may be
losing excess body fat, because you are adding lean muscle mass you may
actually weigh the same. Some of the factors which will determine how
fast you can lose body fat include: