What is obesity?
SummaryObesity is the heavy accumulation of fat in your body to such a degree that it rapidly increases your risk of diseases that can damage your health and knock years off your life, such as heart disease and diabetes.
The fat may be equally distributed around the body or concentrated on the stomach (apple-shaped) or the hips and thighs (pear-shaped). For medical purposes, the body mass index (BMI) is used to determine if your weight is in the healthy range. Doctors use BMI because it compares your weight against your height.
Work out your BMI The BMI figures used in this article apply to adults only. Doctors use special charts to work out BMI for children to take account of differing rates of growth and development.
Take your weight (kg) and divide it by the square of your height (m).
For example, if you weigh 80kg and are 1.7m: 1. Multiply your height by itself 1.7x1.7=2.89 2. Divide your weight by this figure. 3. 80 ÷ 2.89= 27.7kg/m2. 27.7 is the BMI. •You are in the normal range if your BMI is between 18.5 and 25 (kg/m2). •You are overweight if your BMI is between 25 and 30. •You are obese if your BMI is 30 or higher. •You are morbidly obese if your BMI is 40 or higher. How common is obesity? Around one in four men and one in three women in the UK are overweight, according to government statistics.While slightly more women than men are obese (24 per cent versus 23 per cent), in the last ten years there has been a greater increase in the number of men who are obese. The Department of Health predicts that if this trend continues, by 2010 around 6.6 million men will be obese compared to 6 million women.Stomach obesity, where weight is concentrated on the tummy, is the most common type of obesity and affects 30 per cent of adult men.
Obesity and stomach obesity are rapidly increasing, especially in young people. Around one in three children between the ages of 2 and 15 are overweight. While in total more girls than boys are overweight, a greater number of boys are obese.
•14 per cent of boys are overweight. •17 per cent of girls are overweight. •19 per cent of boys are obese. •18 per cent of girls are obese. Government statistics also show that children are more likely to have a weight problem if one parent is overweight, and this risk is increased if both parents are overweight or obese.
What problems can obesity cause? Psychologically, being overweight can affect your body image and damage self-esteem. In some cases this can cause social anxiety and depression.
•Common physical problems include: •difficulties breathing •difficulties walking or running •increased sweating •pain in the knees and back •skin conditions such as acne •gallstones.
The following medical conditions are also more common in obese people than in those of normal weight:
•high blood pressure •high cholesterol •diseases related to hardening of the arteries such as heart attack and stroke (cardiovascular disease). •Type 2 diabetes •some types of cancer.
These conditions are often known as obesity-related diseases and are some of the most common causes of death before the age of 75. This is why obesity increases your risk of mortality.
What causes obesity? Obesity can be hereditary, so some people are at increased risk.Genetic factors can affect appetite, the rate at which you burn energy (metabolic rate) and how the body stores fat. Examples of genetic diseases are polycystic ovary syndrome (PCOS) and hypothyroidism. But even if your genes make weight gain more likely, it is not inevitable that you will be overweight.
Obesity develops from: •overeating •irregular meals •lack of daily physical activity.
This is why obesity has trebled since 1980, when only 6 per cent of men and 8 per cent of women were obese. In this time our lifestyles have changed rapidly, with the ready availability of convenience foods and car journeys replacing walks to work and school. It is lifestyle that determines how the genes develop. Medicines such as antidepressants, corticosteroids and oral contraceptives can also cause weight gain.
When is obesity dangerous? If you have a BMI of more than 25, you should lose weight. The same is true if you carry too much fat around the middle because this increases your risk of heart disease and diabetes.
Your waist should be no more than 102cm/40" (men) or 88cm/35" (women), with stricter targets for Asians of less than 90cm/35" (men) and 80cm/32" (women). To reduce your risk of cardiovascular disease further, you should watch your waistline and make sure it's no more than 94cm/37" (men) and 80cm/32" (women).
How is obesity treated? Initially, your doctor will suggest you lose weight through a change in diet and an increase in physical exercise. Clinical guidelines are to aim for a weight loss of between 5kg and 10kg (11-22lb) over three months. This equals about 0.5kg or 1lb per week.
If you are obese, losing this amount will have a positive effect on your risk of cardiovascular disease and diabetes by reducing blood pressure, blood sugar (glucose) and cholesterol levels.
A dietitian can help you lose weight by giving nutritional advice on buying and preparing foods and designing a weight-loss plan.Weight-loss plans are usually based on a low-fat diet of between 1500 and 2000 calories a day, which will result in a weight loss of 5 to 10kg in more than 90 per cent of obese people.
How do diet and exercise help? Your body needs a certain amount of energy (calories) each day. Excess energy is stored as fat. The more active you are, the more calories your body needs. By eating less than your body needs and exercising more, you force your body to use its existing fat stores for energy.By burning excess fat, you lose weight.
When is medical treatment necessary? Your doctor will usually only consider medicines for weight-loss if changes to diet and exercise are not effective.Two medicines for weight-loss are available on the NHS: orlistat (Xenical) and sibutramine (Reductil).Another weight-loss drug called rimonabant (Acomplia) has been recently launched, but until its cost-effectiveness has been assessed it is unlikely to be widely available on the NHS. You will still need to follow a calorie-controlled diet and start an exercise plan while taking these drugs.
Treatment with Xenical and Reductil will only be continued after three months if you have lost 5 per cent of your body weight in that time. While these medicines can help you to lose weight, there may be a gradual reversal of any weight loss after you stop treatment. To help avoid this, you will need to continue with changes to your diet and exercise levels.
Medicines for obesity are not yet recommended for young people under the age of 18 because we have no knowledge of possible negative effects on puberty and later eating behaviour. Orlistat (Xenical) Xenical reduces the amount of fat that is absorbed from the bowels. Your doctor can prescribe this drug if you are obese, or if your BMI is higher than 28 and you have a related risk factor such as high blood pressure, high cholesterol or diabetes.
Sibutramine (Reductil) Reductil acts on chemicals in the brain called serotonin and noradrenaline to make you feel fuller for longer. Your doctor can prescribe this drug if you are obese or have a BMI higher than 27 with a risk factor for heart disease, and you haven't been able to lose weight through lifestyle change within the last three months.
Rimonabant (Acomplia) Acomplia is a new drug that blocks CB1 receptors in the brain and fat tissues that control appetite and the desire for sweet and fatty foods. This reduces appetite and cravings for these types of foods.A doctor can prescribe this drug if you are obese or have a BMI higher than 27 with a risk factor for heart disease.
What about weight reduction surgery? You can be considered for weight-loss surgery if you are morbidly obese, or if you have a BMI between 35 and 40 and have a risk factor for an obesity-related disease. This type of surgery is known as bariatric surgery.
Gastric banding Gastric banding or 'lap banding' limits the capacity of the stomach so you feel full after eating a small amount of food. Keyhole surgery is used to tie an inflatable band around the top part of the stomach, creating a small pouch at the top. This limits the amount of food your stomach can hold. Food then slowly passes from the pouch into the lower part of your stomach and on into your digestive system. The operation is reversible.
Gastric bypass Gastric bypass is permanent surgery on the stomach to reduce the length of the digestive tract and stop food being absorbed. A small pouch is created at the top of the stomach. Part of the intestine is then grafted to the top of this pouch so food bypasses the stomach and much of the intestine, meaning it can't be digested.
Gastric balloon insertion Gastric balloon insertion is a less permanent type of surgery. It is not widely available on the NHS. A balloon is placed on the end of a thin, flexible tube called an endoscope. It is inserted into your stomach via your mouth. Liquid or air is then pumped into the balloon so it partially fills the stomach. This creates a feeling of fullness. The balloon is usually removed after six months.
In the long term While plenty of diets and slimming products claim to offer quick fixes, obesity is not something that can be cured or brought under clinical control within a few weeks or months. Treatment such as diet and exercise may need to continue for years. Weight-loss plans from a GP or dietician are an effective way to lose weight, but a greater challenge is to achieve a way of life that maintains weight and reduces the chances of putting it back on. This can only be achieved by permanently changing your eating and exercise habits.
Further information BOSPA (British Obesity Surgery Patient Association) has information on many types of weight-loss surgery: www.bospa.org National Obesity Forum: www.nationalobesityforum.org.uk
This feature is based on information contained on netdoctor.co.uk