Obesity and Overweight in Adults

If you are obese or overweight, you have an increased risk of developing various health problems. Even a modest amount of weight loss can help to 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. See also separate leaflet called Obesity and Overweight in Children.

If you are obese or overweight, this means that you are carrying excess body fat. Being overweight or obese is not just about how you look. Over time, it means that you have an increased risk of developing various health problems. As an adult, you can find out whether you are overweight or obese and whether your health may be at risk, by calculating your body mass index (BMI) and measuring your waist circumference.

Body mass index (BMI)

People are different heights and builds, so just weighing yourself cannot be used to decide if your weight is healthy. BMI is used by healthcare professionals to assess if someone's weight is putting their health at risk. It is a measure of your weight related to your height.

To calculate your BMI, you divide 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.

If you do not have scales at home, your practice nurse can measure your height, weigh you and calculate your BMI or try out our BMI calculator.

The table below shows how to interpret your BMI. In general, the more your BMI is over 25, the more overweight or obese you are and the greater the risk to your health.

BMIClassed AsHealth Risk
Less than 18.5UnderweightSome health risk
18.5 to 24.9IdealNormal
25 to 29.9OverweightModerate health risk
30 to 39.9ObeseHigh health risk
40 and overVery obeseVery high health risk

On the whole, BMI is a good estimate of how much of your body is made up of fat. However, BMI may be less accurate in very muscular people. This is because muscle weighs heavier than fat. So, someone who is very muscular may have a relatively high BMI due to the weight of their muscle bulk but actually have a proportionally low and healthy amount of body fat.

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Waist circumference

If you are overweight, measuring your waist circumference can also give some information about your risk of developing health problems (particularly coronary heart disease and type 2 diabetes). If two overweight or obese people have the same BMI, the person with a bigger waist circumference will be at a greater risk of developing health problems due to their weight. This is because it is not just whether you are carrying excess fat but where you are carrying it. The risks to your health are greater if you mainly carry a lot of extra fat around your waist ('apple-shaped'), rather than mainly on your hips and thighs ('pear-shaped').

The easiest way to measure your waist circumference is to place the tape measure around your waist at belly button level.

As a rule for a man:

  • If you have a waist measurement of 94 cm or above, the risk to your health is increased.
  • If you have a waist measurement of 102 cm or above, the risk is even higher.

As a rule for a woman:

  • If you have a waist measurement of 80 cm or above, the risk to your health is increased.
  • If you have a waist measurement of 88 cm or above, the risk is even higher.

Note: for people from Asian backgrounds, the increased health risks may start at a lower waist circumference. Your doctor or practice nurse can advise.

If you are overweight or obese, from day to day you may:

  • Feel tired and lacking in energy.
  • Experience breathing problems (for example, shortness of breath when moving around, or not being able to cope with sudden bursts of physical activity like running across the road).
  • Feel that you sweat a lot compared with other people.
  • Develop skin irritation.
  • Have difficulty sleeping.
  • Get complaints from your partner that you snore.
  • Experience back and joint pains which can affect your mobility.

You may also have an increased risk of developing:

Many people can also develop psychological problems because of being overweight or obese. For example: low self-esteem; poor self-image (not liking how you look); low confidence; feelings of isolation. These feelings may affect your relationships with family members and friends and, if they become severe, may lead to depression.

Being obese (having a BMI >30) can also affect your overall life expectancy: you are more likely to die at a younger age. An analysis in 2009 of almost one million people from around the world showed that if you have a BMI between 30 and 35, you are likely to die 2-4 years earlier than average. If your BMI is between 40 to 45, you are likely to die 8-10 years earlier than average.

Another analysis showed that if you are a woman who is obese at the age of 40, you are likely to die 7.1 years earlier than average. If you are a man who is obese at the age of 40, you are likely to die 5.8 years earlier than average. If you smoke as well, your life expectancy is reduced even further.

Overweight and obesity are common. In the UK:

  • Between 6 and 7 out of 10 men have a BMI >25 and so are overweight or obese.
  • Between 5 and 6 out of 10 women have a BMI >25 and so are overweight or obese.
  • Around 1 in 4 men and 1 in 4 women in the UK have a BMI >30 and so are obese.
  • Around 2 in 100 adults are severely (also called morbidly) obese (BMI >40).

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 and the UK now has the highest rate of obesity in Europe . This has been called the obesity epidemic.

In some respects, the cause sounds quite simple. Your weight depends on how much energy you take in (the calories in food and drink) and how much energy your body uses (burns) up:

  • If the amount of calories that you eat equals the amount of energy that your body uses up, then your weight remains stable.
  • If you eat more calories than you burn up, you put on weight. The excess energy is converted into fat and stored in your body.
  • If you eat fewer calories than you burn up, you lose weight. Your body has to tap into its fat stores to get the extra energy it needs.

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 your body needs to keep 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 may lead to weight gain, include the following.

How much you eat and drink

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 people eat are those higher in calories (particularly fatty and sugary foods), so-called energy-dense foods. Although your body gives you a feeling of fullness after eating enough (satiety), you can easily ignore this feeling if you are enjoying tasty foods. Food portion sizes in general have increased. There has also been a tendency to eat out more over recent years. If you eat out, you are more likely to eat food that is more energy-dense than you would eat at home. The amount of processed foods and ready-made meals available has also increased in response to our busy lives. These are often foods that are more energy-dense as well. However, even healthy foods contain calories and can tip the energy balance if we eat too much of them.

What you drink is also important. Alcohol and sugary drinks contain a lot of calories. Even fresh fruit juices that you may think are healthy can make up a significant part of your daily calorie intake if you drink too much of them.

In short, many people are overweight or obese simply because they eat and drink more than their body needs.

Your physical activity levels

Where does physical activity fit in to your current lifestyle? Most people in the UK do not do enough physical activity. Fewer people these days have jobs which are energetic. The variety of labour-saving devices and gadgets in most homes and the overuse of cars, means that most people end up using up much less energy compared with 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.

Genetics

You are more likely to be obese if one of your parents is obese, or both of your parents are obese. This may partly be due to learning bad eating habits from your parents. But, some people actually inherit a tendency in their genes that makes them prone to overeat. So, 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 you eat, certain hormones and brain chemicals send messages to parts of your brain to say that you 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.

However, 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. But you are likely to struggle more than most people where your weight is concerned. You may find it more difficult to stop yourself from gaining weight or to lose weight.

Medical problems

Less than 1 person in 100 obese people has a 'medical' cause for their obesity. For example, conditions such as Cushing's syndrome and an underactive thyroid are rare causes of weight gain. Women with polycystic ovary syndrome may also be overweight. (See separate leaflets called Cushing's Syndrome and Polycystic Ovary Syndrome for further details on these conditions.)

Some medicines such as steroids, some antidepressants, sulfonylureas and sodium valproate may contribute to weight gain. If you give up smoking, your appetite may increase and, as a result, you may put on weight. People with low mood or depression may also have a tendency to eat more energy-dense 'comfort' foods and so gain 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. But there are also definite health benefits from losing some weight. As explained above, many diseases are more common in obese and overweight people and you are less likely to develop them if you lose some weight.

What is more, if your BMI is between 25 to 35, much of the health benefits come with losing the first 5-10% of your weight. (For example, if you weigh 90 kg and you lose 9 kg, this would be 10% of your original weight.) If your BMI is between 25 to 35, on average, if you reduce your weight by 10%:

  • You are much less likely to develop the health problems listed above, such as diabetes.
  • If you already have problems such as high blood pressure, high cholesterol, osteoarthritis, or diabetes, these 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. This is mainly because you are less likely to die from heart disease, stroke, diabetes, or obesity- related cancers.

If your BMI is more than 35, you are more likely already to have health problems related to being overweight. You will probably need to lose between 15-20% of your original weight to have sustained improvements in these health problems and other health benefits.

If you are worried that you are overweight or obese, you should discuss this with your practice nurse or doctor. They may be able to determine if your weight is already affecting your health.

For example, they may start by checking whether you have any symptoms of coronary heart disease such as chest pains, particularly on exertion. They may also ask about any symptoms of osteoarthritis such as back pain or joint pains, or any symptoms of sleep apnoea this is when your breathing patterns are disturbed while you are sleeping, due to excess weight around your chest, neck and airways. They may suggest some tests to screen for any underlying health problems that may be caused by your weight. For example, they may suggest:

  • A blood test for type 2 diabetes.
  • A blood test to look at your cholesterol and triglyceride levels.
  • A blood pressure check.

Other blood tests are sometimes suggested to look for other problems such as an underactive thyroid gland or liver problems.

As mentioned above, quite often it can also be the case that if someone is overweight or obese, this can lead to psychological problems. So, your doctor or nurse may also ask you questions to look for any signs of these.

Note: your doctor or practice nurse may also be a source of help if you would like to lose weight (see below).

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Doctors and patients can use Decision Aids together to help choose the best course of action to take.

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Some people lose weight by strict dieting for a short period. However, as soon as their diet is over, they often go back to their old eating habits and their weight goes straight back on. Losing weight and then keeping it off, needs a change in your lifestyle for life. This includes such things as:

  • The type of food and drink that you normally buy.
  • The type of meals that you eat.
  • Your pattern of eating.
  • The amount of physical activity that you do.

Another separate leaflet in this series, called Weight Reduction - How to Lose Weight provides more details. Below is a brief summary of the principles in losing weight.

Before you start

  • Motivation is crucial: no weight loss plan will work unless you have a serious desire to lose weight. You need to be ready and motivated.
  • Monitor your current food intake: it is helpful to know exactly how much you currently eat. Keeping a detailed diary of everything that you eat and drink over an average week is more helpful.
  • Aim to lose weight gradually: it is best not to lose weight too fast. Aim to lose an average of 0.5 to 1 kg per week (about 1-2 lb per week).
  • Set clear goals with a realistic timescale: it is important to set a clear and realistic weight loss goal. As mentioned above, in most cases, health benefits can be gained from losing the first 5-10% of your weight.

Aim to eat a healthy balanced diet

Special diets which are often advertised are not usually helpful. This is because after losing weight, if your old eating habits remain, the weight often goes straight back on. It is usually not a special diet that is needed but changing to a healthy balanced diet, for good.

Briefly, a healthy diet means:

  • Making up a third of most meals with starch-based foods (such as cereals, bread, potatoes, rice, pasta). Wholegrain starch-based foods are preferable.
  • Eating plenty of fibre in your diet. Foods rich in fibre include wholegrain bread, brown rice and pasta, oats, peas, lentils, grain, beans, fruit, vegetables and seeds.
  • Having at least five portions, or ideally 7-9 portions, of a variety of fruit and vegetables per day. These should be in place of foods higher in fat and calories. For example, fruit makes a good, healthy snack if you feel hungry.
  • Limiting fatty food such as fatty meats, cheeses, full-cream milk, fried foods, butter, etc. Use low-fat options where possible. Examples are:
    • Skimmed or semi-skimmed instead of full-cream milk.
    • Using low-fat, monounsaturated or polyunsaturated spreads instead of butter.
    • If you eat meat, eating lean meat or poultry such as chicken.
    • Try to grill, bake or steam rather than fry food. If you do fry food, choose a vegetable oil such as sunflower, rapeseed or olive.
  • Avoiding sugary drinks and sugary foods such as chocolate, sweets, biscuits, cakes, etc.
  • Limiting other foods likely to be high in fat or sugar such as some takeaway or fast foods.
  • Eating three meals a day and not skipping meals. Always have breakfast. Eat each meal slowly. Skipping meals will just make you feel more hungry, make you think more about food and make you more likely to overeat in the evening or snack between meals.
  • Trying not to add salt to food and avoiding foods that are salty.
  • Including 2-3 portions of fish per week, at least two of which should be 'oily' (such as herring, mackerel, sardines, kippers, pilchards, salmon, or fresh tuna).

Another separate leaflet called Healthy Eating gives more details.

Look at your eating habits

For example:

  • Plan your meals ahead of time so you know what you will be eating.
  • Be careful that your food portion sizes are not too big.
  • Avoid second helpings when you are already full.
  • Switch unhealthy snacks and desserts to healthy ones.
  • Eat slowly.
  • Don't skip meals.

Be careful about what you drink

Many people use drinks full of calories to quench their thirst. Sugary drinks such as cola, tea and coffee with milk and sugar, milk and alcoholic drinks, all contain calories. One of the easiest ways to cut back on calories is simply to drink water as your main drink.

Increase your physical activity levels

It is recommended that all adults should aim for 150 minutes of exercise a week. One way to do this is to do 30 minutes of moderate-intensity exercise in bouts of 10 minutes for five days of the week. Another method is to do 75 minutes of vigorous-intensity activity spread throughout the week or a combination of moderate and vigorous activity.

Moderate physical activity includes: brisk walking, jogging, dancing, swimming, badminton, tennis, etc. In addition, try to do more in your daily routines. For example, use stairs instead of lifts, walk or cycle to work or school, etc. Avoid sitting for too long in front of the television or a computer screen. Take regular breaks whilst working. The good news is that you don't have to do this physical activity all in one chunk. You can break it up into blocks of 10-15 minutes. See separate leaflet called Physical Activity for Health, which gives more details.

Build your exercise levels up gradually. If you are not used to physical activity, try starting with a 30-minute brisk walk every day and then building up from there.

Monitor your behaviour and progress

Just as keeping a food diary can be helpful at the beginning of a weight loss programme, it can be useful as a way to monitor your eating during your weight loss. You can use the same diary to keep a track of your physical activity levels as well. It is also important to weigh yourself regularly to monitor your progress. Once weekly is recommended. However, don't be disheartened by minor weight increases or levelling off for a few days. Look for the overall trend over several months.

Get help and support

Some people may feel motivated enough and feel that they have all of the information that they need in order to lose weight without any help from others. However, you don't have to try to lose weight alone. There is a wealth of help available. Ask your doctor or practice nurse for advice. A referral to a dietician may be helpful. One-on-one counselling or group counselling may be available in your area on the NHS. Ask about groups or programmes to increase your physical activity levels. There are also a number of commercial weight loss groups that run in the UK as well as internet-based programmes and self-help books that can help you with your weight loss.

Medication to help with weight loss may be an option for some people who want to lose weight. However, there are no wonder drugs available. Lifestyle changes to improve diet and increase physical activity are still important.

A medication called orlistat is available on prescription from your doctor and low-dose orlistat is also available to buy over-the-counter in pharmacies. Doctors and pharmacists are given specific guidelines on when orlistat should be used. A separate leaflet called Orlistat - Help With Weight Loss gives further details.

This may be an option if you are very obese. However, surgery is usually only offered if you have already tried other ways to lose weight which have not worked (including diet, increasing your physical activity levels and orlistat). Surgery usually has very good results and most people do lose a lot of weight. However, this is specialist surgery and it is a major undertaking. Surgery to help weight loss is called bariatric surgery. For further information about surgery to help with weight loss, see separate leaflet called Surgery for Obesity.

Many people lose weight but at the end of their diet, the weight goes back on. The main reason this happens is because their weight-reducing diet was only a temporary change to their unhealthy diet and lifestyle. To keep your weight off, it is important that you make permanent changes. This usually means:

  • Keeping to a healthy diet.
  • Exercising regularly.
  • A change for the whole household. It is difficult for one member of a household to shop and eat differently to the rest. It is best that the whole household should eat a healthy diet.

It does not mean less enjoyment of food. However, it may take a while to learn to enjoy different foods, meals and recipes. Some people need more support to keep to their new weight than when they were actually dieting and losing weight. A local support group may be able to help.

Yes. You can help to prevent becoming overweight or obese by:

  • Following the healthy eating guidelines outlined above.
  • Doing 150 minutes of physical activity according to the guidelines above.
  • Spending less time being sedentary (for example, less time in front of your computer or watching TV).
  • Weighing yourself from time to time so that you become more aware of your weight and you can do something about your weight if you start to put some on.
  • Encouraging a healthy lifestyle for your whole family.
Original Author:
Dr Tim Kenny
Current Version:
Peer Reviewer:
Prof Cathy Jackson
Last Checked:
01/03/2013
Document ID:
4421 (v41)
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