KEEPING HEALTHY - Diet and Exercise
Balanced nutritious food intake and doing some regular 'aerobics' to help reduce
the risk from some non-communicable diseases, obesity indexes
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What constitutes a healthy balanced diet? Why do we need protein in our diet? Why do we need both fats and carbohydrates in
our diet? Why is regular exercise good for? What is metabolism?
Sub-index for this page
What is a healthy
Metabolism and body mass
Aerobic exercise reduces risk from some non-communicable diseases
Know that inherited factors also affect
obesity - body mass index and waist-to-hip ratio
Respiration - aerobic and anaerobic
Keeping healthy - non-communicable diseases
- risk factors for e.g. cancers
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Diet and exercise
What is a healthy balanced diet?
Know that a healthy diet contains the
right balance of the different foods you need and the right amount of
energy and the different food groups are ...
Carbohydrates and fats are
needed to provide energy for your body chemistry to function correctly, and
of course to keep you warm at 37oC,
but, not too much, or
excessive fats or carbohydrates build up in your body which can lead to obesity.
Obesity is a common disorder in
developed countries eg in Europe and the US.
Obesity is defined as 'having a
body mass of at least 20% greater than the maximum recommended body mass.
Although the usual causes of
obesity are overeating, lack of sufficient exercise and bad diet, hormonal
problems can also help cause obesity.
Obesity can contribute to other
medical problems eg arthritis (joint inflammation), type 2 diabetes (failure
to control blood sugar levels), high blood pressure and heart disease and
even some types of cancer.
If you have too much saturated
fat in your diet, your blood cholesterol levels are raised above what is
needed and deposits form on the walls of your blood vessels leading to
higher blood pressure.
Proteins are used by the body to build cells
- growth of new tissue, cell repair and cell replacement.
Mineral ions and vitamins are needed in small
amounts for healthy functioning of the body - organs, skin, bones etc.
Fibre keeps everything
moving smoothly through your digestive system.
A person is malnourished if
their diet is not balanced.
Lack of a good healthy diet can
cause a person to be overweight or
An unbalanced diet may also lead to deficiency diseases or
conditions such as Type 2 diabetes.
You need to eat the right types
of healthy food and in the right amounts/proportions to maintain a healthy
People who live on a poorly
balanced diet are malnourished and malnourishment is common in
the poorer developing countries of the world eg in Africa.
Don't confuse with starvation, where there is not enough food of any description to
maintain life - the pictures you see on your TV of very thin people in
Africa, on the edge of life exemplifies this pitiful state.
However, malnourished people can
be overweight as well as thin, from an imbalanced diet eg those fat people
who live off too much junk food and excess fat are as malnourished in some
ways just as much as a 'thin' person in a poor third world country!
The effects of malnutrition do
depend on what is missing from the diet but common symptoms are slow growth
in children (arrested development), weight loss in adults, poor resistance
to disease and infection, fatigue (low physical activity, lack of energy).
Particular deficiency diseases
are caused by lack of specific vitamins or minerals eg lack of vitamin C
causes scurvy which leads to problems with gums, the skin and joints. Tissue
is not efficiently repaired and ulceration is common.
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Metabolism and body mass
is your metabolism? What is metabolic rate?
The rate at which all the
chemical reactions in the cells of the body are carried out (the metabolic
rate) varies with the amount of activity you do and the proportion of muscle
to fat in your body.
A person loses mass when the
energy content of the food taken in is less than the amount of energy
expended by the body.
need energy to fuel the chemical reactions in your body to keep you alive
and these reactions are called your metabolism.
Different people have small
differences in their resting metabolic rates because eg muscle needs more
energy than fatty tissue, so more muscular people tend to have a higher
metabolic rate because of the higher ratio of muscle to fat.
Bigger people tend to have a
higher metabolic rate because more energy is needed to maintain a greater
mass of cells.
On average men tend to have a
greater metabolic rate because they tend to have a greater proportion of
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Regular aerobic exercise can reduce
your risk from some non-communicable diseases
If you have a high resting heart
rate (measured by your 'pulse') and you are slow to recover from
physical exercise, you should be aware these observations are linked
to an increased risk of developing heart disease (CVD,
Regular exercise can
reduce your resting heart rate and speed up your recovery rate after
engaging in physical activity e.g. brisk walking, manual work,
climbing stairs, jogging etc.
This has been clearly shown from
scientific studies e.g.
You take a biggish number of
volunteers (say a hundred) that do not exercise regularly.
Record their initial baseline
resting heart rate.
Get them all to do the same
physical exercise and record their recovery rate - that is the time
it takes for the increased heart rate to fall back to the resting
You then split the volunteers
into two groups and ask one group to do some regular exercise
every day e.g. brisk walking for an hour or 20 minutes on an
'aerobic exercise machine', and the other group asked to continue in
their normal 'non-aerobic' lifestyle.
After, say 2 months, remeasure
all their resting heart and recovery rates, and you should find a
definite improvement in these figures in the group who did regular
extra aerobic exercise.
Exercise increases the amount of energy expended by
Athletes or people engaged
in heavy manual work would need a greater energy (calorie) intake.
Your metabolic rate can stay up
even after you have finished engaging in more physical exercise,
particularly if it has been strenuous.
Regular exercise can increase
your metabolic rate because it builds muscle as well as using more energy
due to performing more physical activities than just sitting around.
People who have more active
physical jobs need more energy and hence more carbohydrates or fats ie your
dietary needs vary with your occupation.
Exercise increases the amount of
energy (via fat/carbohydrate etc.) used by the body and so decreases the
amount stored as fat, hence less chance of suffering from obesity.
Exercise also builds up muscle
which boosts your metabolic rate.
If you do little exercise and
have a job sitting in an office, you should reduce your carbohydrates and fats
intake accordingly because you need less energy to get through the day.
A note of caution - being fit
does not necessarily mean you are healthy, a common assumption! You can be
unhealthy because of a lack of balanced diet but you could still be
physically non-obese and fit.
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Know that inherited factors also affect
our health e.g.
Metabolic rate may be affected by
Your DNA profile ==> gene
expression ==> inherited characteristics, can have some bearing on your
metabolic rate eg an underactive thyroid gland which can lower metabolic
rate, increase fatigue and ultimately cause obesity. Any energy not used
will be stored as fat.
People can inherit factors that
affects the blood cholesterol level. Cholesterol is an essential fatty
substance for good health and its in every cell in the body but if it is too
high it causes fatty deposits on the inner surfaces of blood vessels causing
higher blood pressure and heart disease.
People who exercise regularly
are usually healthier than people who take little exercise.
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(e) Measures of obesity (one measure of healthiness and
There is no such thing as the 'perfect
weight', we come in all shapes and sizes, but there are limits
within which we should be to be healthy!
In the medical profession, a doctor can't just
simply that somebody is overweight, without reference to some kind
of statistical index, usually by one/both of the ratios described
Equally healthy people can have quite
different weights, but there are some reasonably good indicators as
to when your weight is not what it should be 'ideally'.
In rich developed countries we are often
dealing with 'overweight' people eating too much rich fatty food,
but in poorer underdeveloped countries we are dealing 'underweight'
people, particularly young children suffering from malnutrition.
means lack of proper nutrition, caused by not having enough to eat,
not eating enough of the right things, or being unable to use the
food that one does eat.
The Body Mass Index
The body mass index is a 'rough' guide to help
the medical profession decide whether you are underweight, normal,
overweight or obese - based on your height and height.
The higher your BMI the more fat you are
carrying - but not necessarily unhealthily.
Body Mass Index (BMI) = (body mass in kg) /
(height in m)2
When measured, you then consult a table of BMI
values to se where you fit in!
Table of BMI values (from
|Body mass index
|less than 18.5
|18.5 to 24.9
|25.0 to 29.9
|30.0 to 40.0
If you eat too much fatty sugary foods and
don't take enough exercise, most people will put on weight and too
much of it. You are taking in too much energy rich food for your
The excess energy releasing food is stored as
fat and gives you a raised BMI value.
Having a higher than normal BMI value
increases your risk of developing type 2 diabetes.
Note of caution: Having a high BMI is not
always unhealthy e.g. athletes train hard to build up extra muscle
which is heavier than fat, so they will tend to have higher than
'normal' BMI values and would not be classed as overweight.
Note from 2020 on the covid-19 flue pandemic:
Research has shown that obese people are more likely to be seriously
ill with the virus than non-obese people - more severe fever, more
likely to be hospitalised and more likely to die!