Obesity and Overweight

If you are obese or overweight, you have an increased risk of developing various health problems. A realistic aim for many people is to lose 5-10% of your weight over three months. This is often about 5-10 kg. (10 kg is about one and a half stone.) This modest amount of weight loss will greatly reduce your increased health risks. The best chance of losing weight, and keeping the weight off, is to be committed to a change in lifestyle. This includes eating a healthy diet and doing some regular physical activity.

Are you obese or overweight?

Body mass index
Your body mass index (BMI) is a good estimate of how much of your body is made up of fat. It relates your weight to your height. You can work out your BMI by dividing your weight (in kilograms) by the square of your height (in metres).

So, for example, if you weigh 70 kg and are 1.75 metres tall, your BMI is 70 / 1.75 x 1.75, which is 22.9. Alternatively, your practice nurse can measure and weigh you, and tell you your BMI.BMI Classed As Health Risk
Less than 18.5 Underweight Some health risk
18.5 to 24.9 Ideal Normal
25 to 29.9 Overweight Moderate health risk
30 to 39.9 Obese High health risk
40 and over Very obese Very high health risk


Waist size
Your increased health risk is greater when the extra fat is mainly around your waist ('apple shaped'), rather than mainly on your hips and thighs ('pear shaped'). As a rule, a waist measurement of 102 cm or above for men (92 cm for Asian men) and 88 cm or above for women (78 cm for Asian women) is a significant health risk.

In short, the heavier you are, the longer your carry the extra weight, and the more the fat is around your waist, the greater your health risk.

How common is obesity and overweight?

More than half the adults in the UK are heavier than recommended. About 2 in 5 adults are overweight, and about a further 1 in 5 are obese. The number of obese people in the UK is rising, particularly among young adults. Since 1980, the number of obese adults in the UK has nearly tripled. This has been called the 'obesity epidemic'.

What are the benefits of losing weight?

It is difficult to measure how much 'quality of life' is improved if you lose some weight. Many people feel better, and have more energy. Some people notice an improvement in their self-esteem.

There are also definite health benefits from losing some weight. Many diseases are more common in obese and overweight people, and you are less likely to develop them if you lose some weight. They include: diabetes, high blood pressure, stroke, heart problems, some types of cancer, arthritis of the back and legs, gallstones, menstrual problems, incontinence of urine, breathing problems, some complications of pregnancy, and depression.

What is more, for most obese or overweight people, much of the health benefits come with losing the first 5-10% of your weight. This is often about 5-10 kg. (10 kg is about one and a half stone.) If you are obese, on average, if you reduce your weight by 10%:
You are much less likely to develop the conditions listed above, such as diabetes.
If you already have high blood pressure, osteoarthritis, or diabetes, these conditions are likely to improve. If you are taking medication for these problems, you may need a reduced dose.
Your chance of dying at any given age is reduced by about 20%. This is mainly because you are less likely to die from heart disease, stroke, diabetes, or obesity related cancers.
What is the cause of being overweight or obese?

In some respects, the cause sounds simple. You put on weight if the amount of energy in the foods and drinks that you eat is greater than the amount of energy that you use. Energy from foods and drinks that you do not use is converted into fat, and stored in the body.

A common wrong belief is to think that if you are overweight or obese, you have a low metabolic rate. (Your metabolic rate or 'metabolism' is the amount of energy that you need to keep your body's functions going.) In fact, if you are obese or overweight you have a normal, or even high, metabolic rate (as you use up more energy carrying the extra weight).

The reasons why 'energy taken in' may not balance 'energy used up', and result in weight gain, include the following.

Food and drink intake
Most people in the UK live where tasty food can be found at almost any time of day or night. Many of the foods that we eat are those with the most energy (fatty and sugary foods). Although our body gives us a feeling of fullness after eating enough (satiety), we can easily ignore this feeling if we are enjoying tasty foods. In short, many people simply eat more than their body needs.

Remember too: alcohol contains a lot of calories, and heavy drinkers are often overweight.

Activity and exercise
Most people in the UK do not do enough physical activity. Less people have jobs which are energetic than previously. The variety of labour saving devices and gadgets in most homes, and the overuse of cars, means that most people need to use-up much less energy compared to previous generations. The average person in the UK watches 26 hours of television per week, and many even more (the 'couch potato' syndrome).

A lack of physical activity by many people is thought to be a major cause of the increase in obesity in recent years.

Inheritance
You are more likely to be obese if one or both of your parents are obese. This may be partly due to learning bad eating habits from overeating parents. However, some people inherit a tendency that makes them prone to overeat. Therefore, for some people, part of the problem is genetic.

It is not fully understood how this 'genetic factor' works. It has something to do with the control of appetite. When we eat, certain hormones and brain chemicals send messages to parts of the brain to say that we have had enough, and to stop eating. In some people, this control of appetite and the feeling of fullness (satiety) may be faulty, or not as good as it is in others.

If you do inherit a tendency to overeat, it is not inevitable that you will become overweight or obese. You can learn about the power of your appetite, ways to resist it, be strict on what you eat, and do some regular physical activity. However, you are likely to struggle more than most people to prevent or overcome weight gain.

Medical problems
Less than 1 in 100 obese people have a 'medical' cause. Conditions such as Cushing's disease and an underactive thyroid are rare causes of weight gain. Some medicines such as steroids, some antidepressants, sulphonylureas and sodium valproate may contribute to weight gain. If you give up smoking, your appetite may increase.