Obesity is a term used to describe somebody who is very overweight with a high degree of body fat. 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 will be turned into fat.

According to the information service NHS Choices, a survey published in 2012 found that just over a quarter of all adults (26 per cent) in England are obese.

Obesity is also an increasing problem in children, with around one out of seven children being classified as obese.

Calories
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 takeaway hamburger, fries and a milkshake can add up to 1,500 calories to your intake.

In addition to this, many people are not physically active. They have jobs that involve sitting at a desk most of the day. They also rely on their cars rather than walking, or cycling. When they relax, people tend to watch TV, browse the internet or play computer games, and rarely take regular exercise. So lots of the calories they consume end up being ‘wasted’ and converted into fat cells.

The Department of Health recommends adults do at least 150 minutes (2 hours and 30 minutes) of moderate-intensity aerobic activity (ie 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.

Causes
Obesity does not just happen overnight, it develops gradually from poor diet and lifestyle choices.
For example, unhealthy food choices could be:
• 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.

Genetics
Some people claim there is no point in losing weight because ‘it runs in my family’ or ‘it is 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.

Weight gain
Medical conditions that can cause weight gain include:
• Cushing's syndrome - a rare disorder that causes over-production of steroid hormones
• polycystic ovary syndrome
• an underactive thyroid gland (hypothyroidism), when 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.

There are a number of ways a person’s weight can be assessed. The most widely used method is the body mass index. The body mass index (BMI) is your weight in kilograms divided by your height in metres squared. You can use the NHS Choices’ BMI healthy weight calculator to work out your own BMI. Visit the ‘lose weight’ section on www.nhs.uk

• 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’)

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.

The risks of obesity
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 or a stroke

In addition, obesity can damage your quality of life and can often trigger depression.

Treatment
There are four main goals in the treatment of obesity:

• to prevent further weight gain
• to gradually lose weight through a combination of a calorie-controlled diet and regular exercise
• to avoid regaining any lost weight
• to improve your general state of health and reduce your risk of obesity-related complications

Some people prefer a one-to one consultation with a trainer or dietician, others prefer taking part in a weight-loss group, which can be organised by the local primary care trust (PCT) or a commercial organisation.  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 GP will be able to advise whether orlistat is suitable for you.

Many people will need help examining and changing unhealthy patterns of thinking and behaviour.

Surgery
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 will not respond to non-surgical treatments, such as lifestyle changes.

Outlook
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.
Even a modest reduction in weight brings important health benefits. Losing weight will significantly reduce your risk of type 2 diabetes and heart disease.

Maintaining a healthy weight
Your local pharmacy team can help you to maintain a healthy weight by providing you with:

• Information on the risks of being overweight and obese
• Tips and advice on diet and exercise
• Information on fitness classes in your area
• Healthy eating and nutritional advice
• Advice on portion control, exercise and food labelling
• Information on products to help aid slimming

Some pharmacies also provide a personalised weight-loss support service to help motivate you to lose weight at a healthy pace. Remember your pharmacies are there to help you stay well, not just to treat you when you are sick.

To find out more about obesity-related issues visit www.nhs.uk or the National Pharmacy Association at www.npa.co.uk