Obesity is a term which is used to describe a person who is very overweight with a high degree of body
fat. There are a number of
ways a person's weight may be assessed. The most widely used method is
body mass index. Body mass index (BMI)
is your weight (in kgs) divided by your height (in metres squared). You can
use the NHS Choices BMI healthy weight calculator in order to work out your own
BMI:
- if your BMI is between 25
and 29, you would be considered overweight
- if your BMI is between 30
and 40, you would be considered obese
- if your BMI is over 40, you
would be considered very obese (known as "morbidly obese").
Obesity is an worsening health problem of the developed world.
Another useful method
is to measure around your waist. People with very fat waists (94cm or more in
men and 80cm or more in women) are more likely to develop obesity-related
health problems.
Being obese increases
your risk of developing a number of serious and potentially life-threatening
diseases, such as:
- type 2 diabetes
- heart disease
- some types of cancer, such
as breast cancer and colon cancer
- stroke.
In addition, obesity
can damage your quality of life and can often trigger depression. If you are pregnant,
being very overweight can cause complications for you and your baby.
There are four main
goals in the treatment of obesity:
- preventing further weight
gain
- gradually losing weight
through a combination of a calorie-controlled diet and regular exercise
- avoiding regaining any lost
weight
- improving general health and
reducing the risk of obesity-related complications.
Some people prefer a
one-to-one consultation with a trainer or dietitian, while others
prefer being part of a weight loss group, which can either be organised by
local clinical commissioning groups (CCGs) or through commercial organisations.
You may want to use an internet application such as the NHS BMI Tracker
tool to monitor your weight.
A medication called
orlistat can aid weight loss, but this should be used in combination with the
steps mentioned above, not as an alternative. Your family doctor will be able to advise
whether orlistat is suitable for you. Many people will also
need help examining and changing unhealthy patterns of thinking and behaviour.
Map of USA showing how obesity affects each of its states.
Weight loss surgery
is used as a last resort to treat people who are dangerously obese. A gastric
band or gastric bypass operation is only available on the NHS to treat people
with potentially life-threatening obesity that does not respond to non-surgical
treatments, such as lifestyle changes.
Most cases of obesity
are caused by a person eating more calories than they burn off, and the unused
calories being turned into fat. Modern lifestyles also do not help:
- there is easy access to
cheap, high energy food that is often marketed aggressively
- people's lifestyles and jobs
are much less active than in the past – many leisure activities,
such as watching television, playing video games and browsing the
internet, are usually done sitting down
- people drive or use public
transport and tend to walk a lot less than they used to.
There are also a
number of conditions that can cause weight gain, such as polycystic ovary
syndrome.
A survey published in
2012 found that just over a quarter of all adults (26%) in England are obese. Obesity is also an
increasing problem in children, with around one in
seven children classified as obese.
There is no
"magic wand" treatment for obesity. Weight loss programmes take
commitment and can be challenging, but they are successful for people who stick
with them. Research looking at
obese people who completed a commercial weight loss programme lasting 12 months
found they lost around 5-10% of their body weight.
While this may not
sound like a great amount, it is important to stress that even a modest
reduction in weight brings important health benefits. Losing this amount of
weight will significantly reduce your risk of developing conditions such
as type 2 diabetes and heart disease.
Causes of obesity
Most cases of obesity
are caused by eating too much and moving too little. If you consume high
amounts of energy from your diet but do not burn off the energy through
exercise and physical activity, the surplus energy is turned into fat.
The energy value of
food is measured in units called calories. The average
physically active man needs 2,500 calories to maintain a healthy weight, and
the average physically active woman needs 2,000. This may sound high, but it
can be easy to reach this limit if you eat certain types of food.
For example, eating a
large take away hamburger, fries and a milkshake can add up to 1,500
calories of your intake. Another problem is
that many people are not physically active, so lots of the calories they
consume end up being "wasted" and converted into fat cells.
Obesity does not just
happen overnight – it develops gradually from poor diet and lifestyle
choices. For example,
unhealthy food choices could include:
- eating processed or fast
food high in fat
- not eating fruit, vegetables
and unrefined carbohydrates, such as wholemeal bread and brown rice
- drinking too much
alcohol – alcohol contains a lot of calories, and heavy drinkers
are often overweight
- eating out a lot – you
may have a starter or dessert in a restaurant, and the food can be higher
in fat and sugar
- eating larger portions than
you need – you may be encouraged to eat too much if your friends or
relatives are also eating large portions
- comfort eating – if you
feel depressed or have low self-esteem, you may comfort eat to make
yourself feel better.
Unhealthy eating
habits tend to run in families, as you learn bad eating habits from your
parents. Childhood obesity can
be a strong indicator of weight-related health problems in later life, showing
that learned unhealthy lifestyle choices continue into adulthood.
Lack of physical
activity is another important factor related to obesity. Many people have jobs
that involve sitting at a desk most of the day. They also rely on
their cars rather than walking or cycling. When people
relax, they tend to watch TV, browse the internet or play computer games, and
rarely take regular exercise.
If you are not active
enough, you do not use the energy provided by the food you eat and the extra
calories are stored as fat instead. The Department of
Health recommends adults do at least 150 minutes (2 hours and 30 minutes)
of moderate-intensity aerobic activity such as cycling or fast walking every
week. However, if you are
obese and trying to lose weight, you may need to do more exercise – in
some cases, up to 300 minutes (five hours) may be recommended.
Regular exercise can help prevent and treat obesity.
Some people claim
there is no point in losing weight because "it runs in my family" or
"it's in my genes". While there are some
rare genetic conditions that can cause obesity, such as Prader-Willi syndrome,
there is no reason why most people cannot lose weight. It may be true that
certain genetic traits inherited from your parents – such as taking
longer to burn up calories (having a slow metabolism) or having a large
appetite – can make losing weight more difficult, but it certainly
does not make it impossible. Many cases where
obesity runs in families may be due to environmental factors, such as poor
eating habits learned during childhood.
Medical conditions
that can cause weight gain include:
- Cushing's syndrome, a rare
disorder that causes the over-production of steroid hormones
- an underactive thyroid gland
(hypothyroidism), where your thyroid gland does not produce enough thyroid
hormone.
Certain medicines,
including some corticosteroids and antidepressants, can also contribute to
weight gain. Weight gain can also be a side effect of taking the combined
contraceptive pill and from quitting smoking.
Symptoms of obesity
Being a little overweight may not cause many noticeable
problems. However, once you are carrying a few extra kilograms (or pounds), you
may develop symptoms that affect your daily life.
Obesity causes
day-to-day problems such as:
- breathlessness
- increased sweating
- snoring
- difficulty sleeping
- inability to cope with
sudden physical activity
- feeling very tired every day
- back and joint pains.
Obesity can also
cause changes you may not notice that can seriously harm your health, such as:
- high blood pressure
(hypertension)
- high cholesterol
levels (fatty deposits blocking your arteries).
Both conditions
significantly increase your risk of developing a cardiovascular disease, such
as:
- coronary heart disease,
which may lead to a heart attack
- stroke, which can cause
significant disability and can be fatal.
Another long-term
problem that can affect obese people is type 2 diabetes. It is estimated that
just under half of all cases of diabetes are linked to obesity. The main
symptoms of diabetes are:
- feeling very thirsty
- going to the toilet a lot,
especially at night
- extreme tiredness.
In addition to the
day-to-day problems of obesity, many people may also experience psychological
problems, such as:
- low self-esteem
- low confidence levels
- feeling isolated in society.
These can
affect relationships with family members and friends and may lead to
depression.
Diagnosing obesity
Body mass index (BMI) is currently used
as the most accurate and reliable way of measuring how overweight you are. You
can use the healthy weight calculator to calculate your BMI. You will need
to know your height and weight. For most adults, a
healthy weight is having a BMI between 18.5 and 24.9. A BMI between 25 and 29.9
is considered overweight. A BMI over 30 is considered obese.
The BMI calculation
cannot take very muscular figures into account. Muscle can add extra weight,
and this may give you an overweight or obese BMI when you are not an unhealthy
weight. For example, a
heavyweight boxer would be classed as obese using the BMI, when he is in fact a
healthy weight. However, for most
people BMI remains an accurate method of assessing weight.
Children and young
people should not use BMI to calculate if they are a healthy weight, as their
bodies are still developing. Instead, children and young people should visit
their doctor, who will be able to tell them if they are overweight or obese for
their height and sex. Most modern leisure
centres have weighing scales that can electronically measure the percentage of
your body weight that is fat. This can be compared with the ideal for your
height, age and sex, and may give you an indication of how overweight you are.
If you are overweight
or obese, visit your doctor to find out if you are at increased risk of
health problems, and how you can safely lose weight. Your doctor will ask about:
- any underlying causes for
your obesity – for example, if you are on certain medication or
have a medical condition that causes weight gain
- your lifestyle –
particularly your diet and how much physical activity you do, and also
whether you smoke and how much alcohol you drink
- how you feel about being
overweight – for example, if you are feeling depressed
- how motivated you are to
lose weight
- your family history of
obesity and other health conditions, such as diabetes (a condition caused
by too much glucose in the blood).
As well as
calculating your BMI, your doctor may also perform tests to determine if
you are at increased risk of health complications because of your obesity.
These could include:
- measuring your blood
pressure
- measuring your waist circumference
(the distance around your waist)
- measuring the glucose
(sugar) and lipid (fat) levels in a sample of your blood.
Your doctor may also
consider your age and ethnicity, as these can affect your risk of certain
conditions. For example, some
people of Asian, African or Afro-Caribbean ethnicity may be at increased risk
of high blood pressure (hypertension), and some older people may be at lower
risk.
Preventing obesity
The best way to prevent becoming overweight, or obese, is by eating
healthily and exercising regularly. As obese children
also tend to be obese in later life, it is important for parents to set
the right example for their children from an early age. You can find more
detailed advice about eating a health diet in the Health A-Z, including
what you should be eating from the main food groups and how much you should be
drinking every day. The Live Well section
contains advice on:
- losing weight
- good food
- fitness.
Eating healthy with lots of fruit and vegetables can help prevent and/or treat obesity.
The National
Institute for Health and Care Excellence (NICE) has produced a booklet
called Treatment for people who are
overweight or obese (PDF, 484kb). It covers NHS care and treatment
of people who are overweight or obese in England and Wales. NICE has also
published Preventing obesity and staying a healthy weight (PDF,
666kb), a booklet about the prevention of obesity and staying a
healthy weight. It aims to help you understand when you might need help
and where you can go to get support.
Treating obesity
If you are obese and you want to lose weight, you should see your doctor. They
will recommend:
- what type of diet you should
be following
- how much exercise you will
need to do
- whether you need further
testing or treatments for obesity-related conditions
- whether you need treatment
for an underlying cause of obesity, such as polycystic ovary syndrome.
Your doctor may refer you
to other services, such as local weight loss groups. These could be provided by
the NHS or may be commercial services you pay for. If it is appropriate,
your doctor may recommend exercise on prescription, where you are referred to a
local active health team for a number of sessions under the supervision of a
qualified trainer. Depending on where you live, the exercise programme may be
free or at a reduced cost.
While there is no
single rule, most obese people are told they have to reduce the energy intake
from their diet by 600 calories a day. The best way to
achieve this is to swap unhealthy and high energy food choices such as
fast food, processed food and sugary drinks (including alcohol) for healthier
choices. A healthy diet should
consist of :
- plenty of fruit and
vegetables
- plenty of potatoes, bread,
rice, pasta and other starchy foods (ideally you should choose wholegrain
varieties)
- some milk and dairy
foods
- some meat, fish,
eggs, beans and other non-dairy sources of protein
- just small amounts of food
and drinks that are high in fat and sugar.
Also avoid food that
contains high levels of salt as this can raise your blood pressure, which can
be dangerous in already obese people. You will also need to
check calorie information for each type of food and drink you
consume to make sure you do not go over your daily limit. Some restaurants,
cafés and fast food outlets provide calorie information per portion, but
providing this information is not compulsory. Be careful – some foods can
quickly take you over the limit, such as burgers, fried chicken and some
curries or Chinese dishes.
You should avoid fad
diets that recommend unsafe practices such as fasting (going without food for
long periods of time) or cutting out entire food groups such as meat, fish,
wheat or dairy products. These are not
sustainable, can make you feel ill, and may cause unpleasant side effects such
as bad breath, diarrhoea and headaches.
This is not to say
that all commercial diet programmes are unsafe. Many are based on sound medical
and scientific principles and can work well in some people. A responsible diet
programme should:
- educate you about issues
such as portion size, making changes to behaviour and healthy eating
- not be overly restrictive in
terms of the type of food you can eat
- be based on achieving gradual
sustainable weight loss rather than short-term rapid weight loss, which is
unlikely to last.
A very low calorie
diet (VLCD) is where you consume less than 1,000 calories a day. An
example of a VLCD would be:
- a bowl of cornflakes for
breakfast
- a single jaffa cake as a
mid-morning snack
- a chicken salad sandwich for
lunch
- a low calorie lasagne for an
evening meal
- a pear for an after-dinner
treat.
This plan also
assumes that you will be drinking water or diet drinks throughout the day, as
most other popular drinks such as tea and coffee contain calories. Remember, excessive
amounts of fizzy diet drinks can damage your teeth – they may not contain
sugar, but they do contain high levels of certain acids.
While a VLCD can be
an effective method of losing weight for some obese people, it is not a
suitable or safe method for everyone. It would usually only be recommended if
rapid weight loss was required to reduce the risk of an obesity-related
complication, such as heart disease, or if you have failed to lose weight
despite conventional treatment. You should only ever
undertake a VLCD under the supervision of a suitably qualified healthcare
professional.
Reducing the amount
of calories in your diet will stop you putting on more weight. But if you
want to lose weight, you have to combine a calorie-controlled diet with regular
exercise. Your doctor or weight
loss adviser will be able to provide an exercise plan suited to your
circumstances, which will probably recommend so many hours of
moderate-intensity physical activity a week.
Moderate-intensity
physical activity is any activity that increases your heart and breathing rate
and may make you sweat, but you are still able to hold a normal conversation. Examples include:
- fast walking
- jogging
- swimming
- tennis
- using a step-trainer or
similar at the gym.
Choose physical
activities that you enjoy, as you are more likely to continue doing them. You should aim to
start gradually – possibly 15 to 20 minutes of exercise five times a day – and
then build on it.
More than 120
different types of anti-obesity medication have been tested in clinical trials,
but only one has proved to be both safe and effective. This medication is
called orlistat.
Orlistat works by
blocking the action of a protein used to digest fat. The undigested fat is not
absorbed into your body and is passed out with your faeces (stools). Orlistat will stop
around one-third of the fat from the food you eat from being digested. This will help you
avoid gaining weight, but it will not necessarily cause you to lose weight. It
is therefore still important to stick to your recommended diet and exercise
plan.
One orlistat capsule
is taken with each main meal (a maximum of three capsules a day). You can take
the capsule either before, during, or up to one hour after each meal. If you miss a meal or
the meal does not contain any fat, you may not need to take the orlistat
capsule. Your docotr must explain this to you, or you can check the patient
information leaflet that comes with your medication.
You should have
made a significant effort to lose weight through diet, exercise or
changing your lifestyle before taking orlistat. Even then, orlistat is only
prescribed if you are on a low calorie diet and you have:
- a body mass index (BMI) of
28 or more and other conditions related to weight, such as high blood
pressure (hypertension)
- a BMI of 30 or more.
Treatment with
orlistat must be combined with a low-fat diet and other weight loss strategies,
such as doing more exercise. If you are prescribed orlistat, you will also be
offered advice and support about diet, exercise and making lifestyle changes. Treatment with
orlistat should only continue beyond three months if you have lost 5% of your
body weight. Orlistat usually starts to affect how you digest fat
within one to two days. If orlistat has not worked after three
months, it is unlikely to be an effective treatment for you.
If you have type
2 diabetes (a condition caused by too much glucose in the blood), it may take
you longer to lose weight using orlistat. Your target weight loss after three
months may therefore be slightly lower. If orlistat is
successful after three months, your prescription may be continued for up to a
year. After that, your doctor will review your condition and decide whether you
should continue with orlistat or not. Side effects of
orlistat include:
- fatty or oily stools
- needing the toilet urgently
- passing stools more
frequently
- oily discharge from your
rectum (you may have oily spots on your underwear)
- flatulence (wind)
- stomach pain
- headaches
- upper respiratory tract
infections, such as a cold or sore throat.
Side effects are much
less likely if you stick to a low fat diet. Women taking the
oral contraceptive pill are advised to use an additional method of
contraception, such as a condom, if they experience severe diarrhoea while
taking orlistat. This is because the
contraceptive pill may not be absorbed by your body if you have diarrhoea, and
so may not be effective. Orlistat is not
suitable for pregnant or breastfeeding women.
Treating obesity in
children is based on much the same principles as treating obesity in
adults – by combining a calorie-controlled diet with regular
exercise. The amount of
calories your child should eat every day will depend on their age and height.
Your family doctor should advise on a recommended daily limit. It is recommended all
children get at least one hour of moderately intense exercise a week, such as
running, playing football or netball.
You should restrict
sedentary activities such as watching television or playing computer games to
less than two hours a day (14 hours a week). It may be better to
gradually introduce these changes to your child's behaviour and then try
to get them to change. Referral to a
specialist in treating childhood obesity may be recommended if:
- your child develops an
obesity-related complication such as high blood pressure, sleep apnoea
(interrupted breathing during sleep) and depression
- it is thought there is an
underlying medical condition causing the obesity, such as a hormonal
condition.
The use of orlistat
in children is only recommended in exceptional circumstances, such as if a
child is severely obese and also has an obesity-related complication.
Surgery for obesity
Weight loss surgery, also called
bariatric surgery, is used as a last resort to treat people who are dangerously
obese (carrying an abnormally excessive amount of body fat). This type of surgery
is only available on the NHS to treat people with potentially life-threatening
obesity that will not respond to non-surgical treatments, such as lifestyle
changes. Potentially
life-threatening obesity is defined as:
- having a body mass index
(BMI) of 40 or above
- having a BMI of 35 or above
and having another serious health condition that could be improved if you
lose weight, such as type 2 diabetes or high blood pressure.
Complications of obesity
Being obese can lead
to serious health problems, as well as shorten your life expectancy. It is estimated that
there around 35,000 obesity-related deaths in England each year. This accounts
for one in every 16 deaths.
Obesity can cause a variety of significant health problems, summarised in this schematic diagram.
Being overweight or
obese can increase your risk of health problems, including:
- high blood
pressure (hypertension) – this is a major risk factor for developing
a serious cardiovascular disease (conditions that can affect the
circulation of blood around the body)
- infertility
- type 2 diabetes
- many types of cancer
- heart disease
- stroke
- asthma
- osteoarthritis – a
condition that affects the joints
- back pain
- depression
- liver disease
- kidney disease
- sleep apnoea –
a condition that causes interrupted breathing during sleep
- gastro-oesophageal reflux
disease.
If you are obese, you
are also more likely to develop complications in pregnancy, such
as gestational diabetes or pre-eclampsia (which is when a woman
experiences a potentially dangerous rise in blood pressure during pregnancy).
Source: NHS Choices.
Source: NHS Choices.