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Obesity in adults

Obesity is a condition in which excess body fat affects your health. It usually happens as a result of eating too many calories (energy) and not doing enough physical activity, but other causes may be involved. Being obese increases your risk of a number of health problems including type 2 diabetescoronary heart disease and some types of cancer.

If you regularly take in more calories than you use up, the extra energy is stored in your body as fat. You will start to gain weight and eventually become obese.

The number of obese adults in the UK has been increasing steadily. In 2011 just under a quarter of all men and just over a quarter of all women in England were obese.

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  • Diagnosis Diagnosis of obesity

    You can work out for yourself whether you’re overweight or obese by working out your body mass index (BMI). You can calculate this by dividing your weight in kg by your height in metres, then dividing the answer you get by your height again. To work out your BMI, see our BMI calculator.

    A healthy BMI is between 18.5 and 24.9. If you have a BMI greater than this, you’re likely to be overweight or obese – these ranges are explained here.

    • 25 to 29.9 – overweight
    • 30 to 39.9 – obese
    • over 40 – severely (or morbidly) obese

    These BMI ranges aren’t appropriate for everyone. For example, if you have a lot of muscle, your BMI may not be an accurate measurement of whether you need to lose weight. In addition, these categories aren’t reliable if you’re from certain ethnic groups including Asian and African-Caribbean. This is because people from these groups are at an increased risk of health problems related to being overweight at lower BMI levels.

    Your waist circumference is another important measure of your health. If you're a man, your health may be at risk if your waist measurement is 94cm (37 inches) or more. For women, a waist measurement of 80cm (31.5 inches) or more may put your health at risk. Again, these measurements vary depending on your ethnic group – speak to your GP for more information. If you’re not sure of your waist size, measure around your body halfway between the bottom of your ribs and the top of your hips.

    It’s only necessary to see your GP if you have already tried to lose excess weight through lifestyle changes but these haven’t helped. So for example you've already tried increasing how much activity you do and reducing how much you eat.

    See your GP if you’re overweight or obese and also have other health problems. He or she may measure your blood pressure and offer you a blood test to check your cholesterol and blood sugar levels.

    Weight loss tips 

    Bupa Health Assessment: BMI

    If you are concerned about your BMI, Bupa can help you get a diagnosis.

  • Treatment Treatment of obesity

    Effective weight loss takes time and effort so think about why you want to lose weight and seek help and support when you’re ready to make changes. There is no quick fix for losing weight.

    If you have decided that you’re ready to change, the best way to achieve a healthy weight is to improve your diet and eating habits. This is likely to be more successful if, at the same time, you increase the amount of physical activity that you do. Making changes with help and support from others is likely to improve your chance of successful weight loss.

    You're more likely to keep the weight off for good if you lose it slowly. This allows time for new, healthier habits to become part of your everyday life. It's important that you're realistic about the amount of weight you want to lose – don’t try to lose more than 1kg (2 lbs) per week. Make sure that you set yourself clear and achievable goals.

    A healthy, balanced diet

    It's important that you follow a balanced diet and control portion size to achieve and maintain a healthy weight. You may need to reduce how much you eat, as well as changing what you eat. Speak to your GP or practice nurse for advice before cutting down if you have any other medical problems.

    The following tips may help you to improve your diet.

    • Base your meals around starchy foods such as potatoes, pasta, bread and rice. Choose wholegrain varieties whenever possible.
    • Include a moderate amount of protein, for example meat, fish, eggs or pulses.
    • Try to limit the amount of food you eat that is high in fat and sugar, such as cakes, biscuits and butter. Cut off any visible fat on meat and take the skin off chicken.
    • When cooking, try to grill, bake, boil or steam food rather than frying it.
    • Introduce more fruit and vegetables into your diet so that you eat at least five portions a day.
    • Aim to eat at least two portions of fish a week, including one of oily fish such as salmon, mackerel or fresh tuna.
    • Alcohol is high in calories and increases your appetite, so reducing the amount you drink can help control your weight.
    • Water is the healthiest thing to drink. You could try adding low-calorie squash or ice and lemon. Remember that some fizzy drinks contain lots of sugar.
    • Only eat snacks if you’re really hungry. If you do, choose healthy options such as fruit or low-fat yoghurt.

    Fad diets and crash dieting

    A fad diet involves eating a very limited range of foods. These diets aren't healthy and although they may lead to short-term weight loss, you’re likely to put the weight back on as soon as you return to your usual eating habits. Don’t dramatically cut down how much you eat as it may mean your body doesn’t get all the nutrients it needs to function healthily.

    Weight-loss programmes

    There are several commercial weight-loss programmes that can help you manage your weight. You may find slimming clubs useful if you like group meetings and think you would benefit from consistent support. There is evidence to suggest that attending regular weekly sessions at a slimming club can be effective at helping people start to lose weight.

    There is a range of online diet programmes available, which can help you lose weight and maintain your weight loss. You may find these helpful if you’re too busy to attend a group but it’s a good idea to also get social support, such as via web chats and online discussion forums.

    Talk to your GP or practice nurse about which options will suit your individual needs and fit in with your lifestyle. He or she can also give you further advice and information about healthy eating. See our frequently asked questions for more information.

    Physical activity

    Although the best way to lose weight is to combine physical activity with healthy eating, if you haven’t been active for some time, it’s important to start slowly and gradually build up how much you do. It may help to start by reducing the amount of time you spend being inactive, for example sitting at a computer or watching television. If you're unsure about starting to exercise, get advice from your GP or practice nurse.Aim to do some physical activity every day. The recommended healthy level is 150 minutes (two and a half hours) of moderate exercise over a week in bouts of 10 minutes or more. You can do this by carrying out 30 minutes on at least five days each week. Alternatively, you can do 75 minutes of vigorous intensity activity spread across the week.

    Moderate means your breathing is faster, your heart rate is increased and you feel warmer. At this level of activity your heart and lungs are being stimulated and this goes towards making you fitter. Depending on your level of fitness, you may need professional supervision.

    It’s a good idea to choose exercise that you can fit into your usual routine, for example brisk walking or gardening. It's important that you find an activity that you enjoy to help you stay motivated. If you find exercise boring on your own, invite a friend to come along or join a local club.

    Click on the image to open our Walk to Run programme.



    If you have been following a programme of managed diet and increased exercise for several months but still haven’t lost a realistic amount of weight, your GP may prescribe a medicine called orlistat. Orlistat prevents your body from absorbing all the fat in your food. It’s recommended for people with a BMI of 30 or higher for whom lifestyle and behaviour changes haven’t been effective. Your GP may prescribe you orlistat if your BMI is 28 or higher and you also have health problems associated with obesity.

    Your GP will discuss the advantages and disadvantages of orlistat with you. The medicine can cause side-effects such as abdominal (tummy) pain and oily faeces. You may also be given information about support programmes. It’s important that you have regular follow-up appointments with your GP to monitor if the medicine is working and if you have any side-effects. See our frequently asked questions for more information.

    Orlistat is also available over the counter but at a lower dose. You will need to talk to your pharmacist before he or she will sell it to you.


    Occasionally, surgery is recommended for obesity. The most common types of surgery are gastric banding and gastric bypass. They involve either reducing the size of your stomach so you eat less, or bypassing part of your gut so your body absorbs less food. You may be able to have surgery if you:

    • have a BMI of 40 or higher
    • have a BMI between 35 and 40 with a disease that could be improved with weight loss (for example diabetes or high blood pressure)
    • have tried other suitable ways of losing weight without any success
    • are fit for surgery and general anaesthesia
    • agree to a long-term treatment follow-up programme

    If you have a BMI of 50 or more, surgery may be the first option. If your GP recommends surgery, he or she will refer you to a specialist. The specialist will talk to you in more detail about the benefits and limitations of the surgery. After the operation, you will work with a specialist obesity team who will help you to make changes to your diet. See our frequently asked questions for more information.

    You may be able to have a new technique called gastric plication. This is keyhole surgery to stitch folds in your stomach to make it smaller. Although this procedure is safe in the short term, because it’s new not much is known about its long-term effectiveness and safety.

  • Causes Causes of obesity

    Eating an unhealthy diet and a lack of exercise are the main causes of obesity. Sweet and fatty foods and sugary drinks contain lots of calories and can cause weight gain if you eat or drink them often. Portion sizes have increased over the last 30 years and now contain more calories, which also increases your risk of becoming obese.

    If you were overweight or obese as a child, or other people in your family are, you're more likely to be obese as an adult. Genetic factors could play a role in this.

    Occasionally medical conditions and medicines can make you put on weight.

  • Complications Complications of obesity

    If you're obese, you're at risk of developing health problems. These include:

    • type 2 diabetes
    • high blood pressure (hypertension)
    • coronary heart disease
    • some types of cancer, including breast and bowel cancer
    • depression
    • sleeping problems, such as snoring and sleep apnoea (a condition in which you frequently stop breathing for a short time while you’re asleep)
    • osteoarthritis and back pain as a result of increased strain on your joints
    • breathlessness

    Women who are obese are more likely to have problems during and after pregnancy.

    If you're obese, it can cause mental health problems, such as low self-esteem and poor body image.

  • Worried about your BMI?

    Get a picture of your current health and potential future health risks with a Bupa health assessment. Find out more today.

  • FAQs FAQs

    Can I take orlistat for obesity if I'm pregnant?


    You will probably be advised not to take orlistat if you're pregnant or breastfeeding.


    Very little research has been done into the effects of weight-loss medicine and pregnancy. Your GP may advise you not to take orlistat if you're pregnant because it reduces your body’s ability to absorb fat and fat soluble vitamins.

    You shouldn’t take orlistat while breastfeeding because doctors don’t know whether or not it passes to your baby through breast milk.

    If you’re sexually active, make sure that you use contraception while taking orlistat. If you take the contraceptive pill and you find that orlistat gives you diarrhoea, use additional contraception such as condoms.

    If you’re planning to have a baby or you have become pregnant while taking weight loss medicine, talk to your GP or pharmacist.

    How much weight will I lose with a gastric band?


    This will depend on a number of factors including your diet and how much physical activity you do after surgery.


    If you're very overweight or obese, you may find it particularly difficult to lose weight with lifestyle measures and medicines so your GP may recommend you have surgery. Losing excess weight is very important because it will reduce your risk of health problems including type 2 diabetescoronary heart disease and high blood pressure.

    Some people don't lose any weight after a gastric band operation, whereas others lose weight but put some or all of it back on. However, on average, you will lose about half of your excess body fat within two years. After surgery you will need to greatly reduce how much you eat and there may be certain foods that you can’t eat at all. You're more likely to lose weight if you stick with this, increase your physical activity, regularly attend follow-up appointments with your healthcare team and keep in contact with a support group.

    I lose weight but always put it back on. How can I prevent this?


    There are a number of things you can do to keep weight off permanently. Eating a healthy, balanced diet and keeping physically active are the best ways of losing excess weight. You will need to continue with these habits to maintain a healthy weight.


    It's important that you have a realistic goal for weight loss and aim to lose weight slowly and steadily. An achievable weight loss is five to 10 percent of your current weight over a period of six months. This reduces your risk of conditions related to obesity, such as coronary heart disease, stroketype 2 diabetes and some cancers.

    Adapting your diet to make it healthier will help to reduce your weight. You’re also likely to need to reduce how much you eat – speak to your GP or practice nurse for advice on cutting down the amount that you eat.

    Physical activity combined with healthy eating can help you lose weight and keep it off. Aim to do some physical activity every day and spend as little time as possible being inactive. The recommended healthy level of physical activity is 150 minutes (two and a half hours) of moderate exercise over a week in bouts of 10 minutes or more. One way to do this is by carrying out 30 minutes on at least five days each week.

    You may find it helps to weigh yourself regularly to see your progress. Measuring your waist is also helpful. If you weigh yourself every day, you’re likely to see your weight going up and down as a result of fluid changes so don't weigh yourself more often than once a week.

    If you have good support from those close to you, you're more likely to continue with a healthy diet and lifestyle. Talk to your family and friends about the things they can do to help you lose weight.

    Once you have reached your target weight, it’s important to keep up the good habits you have started.

    I'm finding it difficult to change what I eat - is there anyone who can help me?


    Yes, talk to your GP if you're having problems improving your diet or reducing how much you eat. He or she may be able to refer you to a dietitian, practice nurse, counsellor or weight-management group.


    You may find that a weight-management group or slimming group gives you the advice, support and motivation that you need. Alternatively, there may be a practice nurse who can advise you on diet and exercise, and encourage you to keep going with your weight loss.

    For some people, a counsellor or psychologist can help by giving individual advice and exploring your emotional relationship with food. He or she can help you find new ways to deal with your feelings.

    A registered dietitian can give you advice on all aspects of your diet. He or she must be qualified to university degree level and registered with the Health Professionals Council to use the title dietitian.

    Talk to your GP to find out more about your options.

  • Resources Resources

    Further information


    • Obesity. NICE Clinical Knowledge Summaries., published October 2012
    • Obesity in adults. BMJ Best Practice., published August 2013
    • Obesity Knowledge and Intelligence. Public Health England., accessed 12 September 2013
    • Statistics on obesity, physical activity and diet – England 2013. Health and Social Care Information Centre., published February 2013
    • Central sleep apnea. The Merck Manuals., published March 2013
    • Obesity and mental health. National Obesity Observatory., published March 2011
    • Assessing body mass index and waist circumference thresholds for intervening to prevent ill health and premature death among adults from black, Asian and other minority ethnic groups in the UK. National Institute for Health and Care Excellence (NICE), July 2013.
    • British Dietetic Association., accessed 1 October 2013
    • Stubbs RJ, Pallister C, Whybrow S, et al. Weight outcomes audit for 34,271 adults referred to a primary care/commercial weight management partnership scheme. Obesity Facts 2011; 4:113–20. doi:10.1159/000327249
    • Losing weight gradually and healthily. NI Direct., published July 2013
    • A healthy varied diet. British Nutrition Foundation., published January 2013
    • Start active, stay active. Department of Health., published July 2011
    • Obesity in adults. Patient Plus., published March 2013
    • Obesity guidance on the prevention, identification, assessment and management of overweight and obesity in adults and children. National Institute for Health and Care Excellence (NICE), December 2006.
    • Joint Formulary Committee. British National Formulary (online). London: BMJ Group and Pharmaceutical Press., accessed 13 September 2013
    • Orlistat: key safety information to support pharmacy availability. Medicines and Healthcare products Regulatory Agency., published May 2009
    • Information station. British Obesity Surgery Patient Association., accessed 13 September 2013
    • Laparascopic gastric plication for the treatment of severe obesity. National Institute for Health and Care Excellence (NICE), November 2012.
    • SPC Xenical 120mg hard capsules. electronic Medicines Compendium., published September 2013
    • Articles. National Obesity Forum., published June 2006
    • The gastric band. Weight Loss Surgery., accessed 13 September 2013
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