Treating obesity 

Speak to your GP if you're obese. They'll be able to advise you about how to lose weight safely.

The best way to lose weight is to combine a healthy, reduced-calorie diet with regular exercise. A dietary approach alone isn't recommended.

Your GP can advise you about the types of food you should be eating (and not eating), how much you should eat, and how you much exercise you should do.

They can also let you know about other useful services in your area such as:

  • local weight loss groups  these could be provided by the NHS or may be commercial services you have to pay for
  • exercise on prescription  where you're referred to a local active health team for a number of sessions under the supervision of a qualified trainer

If you have underlying problems associated with obesity, such as polycystic ovary syndrome (PCOS)high blood pressurediabetes or obstructive sleep apnoea, your GP may recommend further tests or specific treatment. In some cases, they may refer you to a specialist.

Read more about how your GP can help you lose weight.


While there's no single rule that applies to everyone who's obese, most people are advised to reduce the energy intake from their diet by 600 calories a day.

The best way to achieve this is to swap unhealthy and high-energy food choices – such as fast food, processed food and sugary drinks (including alcohol) – for healthier choices.

If you want a healthy, balanced diet you should try to:

  • Eat at least five portions of fruit and vegetables every day. 
  • Base meals on potatoes, bread, rice, pasta and other starchy foods (choose wholegrain varieties where possible).
  • Have some milk and dairy foods or alternatives such as soya drinks and yoghurts, and choose lower-fat and lower-sugar options.
  • Eat some beans, pulses, fish, eggsmeat and other protein. Aim for two portions of fish every week – one of which should be oily, such as salmon or mackerel.
  • Choose unsaturated oils and spreads and eat in small amounts.
  • Drink plenty of fluids – the government recommends 6-8 cups/glasses a day.

If you're having foods and drinks that are high in fat, salt and sugar, have these less often and in small amounts.

Try to choose a variety of different foods from the five main food groups.

Most people in the UK eat and drink too many calories, too much fat, sugar and salt, and not enough fruit, vegetables, oily fish or fibre. Read our page on understanding calories.

Try to avoid foods containing high levels of salt because they can raise your blood pressure, which can be dangerous in people who are already obese. Read some tips for a lower-salt diet.

You'll also need to check calorie information for each type of food and drink you consume, to make sure you don't go over your daily limit.

Some restaurants, cafes and fast food outlets provide calorie information per portion, but providing this information isn't compulsory. Be careful when eating out, as some foods can quickly take you over the limit, such as burgers, fried chicken and some curries or Chinese dishes.

Read more about calorie counting.

Diet programmes and fad diets

Avoid fad diets that recommend unsafe practices, such as fasting (going without food for long periods of time) or cutting out entire food groups. These type of diets don't work, can make you feel ill, and aren't sustainable because they don’t teach you long-term healthy eating habits.

This isn't to say that all commercial diet programmes are unsafe. Many are based on sound medical and scientific principles and can work well for some people. A responsible diet programme should:

  • educate you about issues such as portion size, making changes to behaviour and healthy eating 
  • not be overly restrictive in terms of the type of foods you can eat 
  • be based on achieving gradual sustainable weight loss rather than short-term rapid weight loss, which is unlikely to last

On average, people attending a lifestyle weight management programme lose around 3% of their body weight, although this varies considerably.

Read about the pros and cons of different diets.

Very low calorie diets

very low calorie diet (VLCD) is where you consume less than 1,000 calories a day.

VLCDs can lead to rapid weight loss but they aren't suitable or safe for everyone. They're usually only recommended as part of a wider weight management strategy for people with an obesity-related complication that would benefit from rapid weight loss, such as severe sleep apnoea.

VLCDs should only be used under the close supervision of a suitably qualified healthcare professional, and should only be followed for a maximum of 12 weeks (continuously or intermittently).

Further information

For more information about diet and weight loss read about:


Reducing the amount of calories in your diet will help you lose weight, but if you want to keep the weight off, you have to combine a calorie-controlled diet with regular exercise.

Your GP or weight loss adviser can provide an exercise plan tailored to your circumstances, which will probably involve several hours of moderate-intensity physical activity a week.

Moderate-intensity physical activity is any activity that increases your heart and breathing rate, and may make you sweat, but still allows you to hold a normal conversation. Examples include:

Choose physical activities that you enjoy because you're more likely to continue doing them.

You should aim to start gradually. For example, start off by doing 15 to 20 minutes of exercise five times a week and then build on it.

The Department of Health recommends most adults should do at least 150 minutes (two-and-a-half hours) of moderate-intensity exercise every week. However, if you're obese and trying to lose weight, or have successfully lost weight and want to keep it off, you probably need to do more exercise. In most cases, up to five hours a week is recommended.

Further information

For more information about exercise, see:

Other useful strategies

Evidence has shown that weight loss can be more successful if it involves other strategies, in addition to diet and lifestyle changes. This could include things like:

  • setting realistic weight loss goals  even losing just 3% of your original body weight can significantly reduce your risk of obesity-related complications
  • eating slower and being mindful of what and when you're eating  for example, not being distracted by watching TV
  • avoiding situations where you know you may be tempted to overeat
  • involving your family and friends with your weight loss efforts they can help and motivate you
  • monitoring your progress  for example, weighing yourself regularly and noting your weight in a diary

You may also find psychological support from a trained healthcare professional helps you change the way you think about food and eating, through techniques such as cognitive behavioural therapy (CBT).


Many different types of anti-obesity medication have been tested in clinical trials, but only one has proved to be both safe and effective: orlistat.

Orlistat works by preventing around a third of the fat from the food you eat from being digested. This undigested fat isn't absorbed into your body and is passed out with your faeces (stools).

This will help you avoid gaining weight, but won't necessarily cause you to lose weight. Therefore, it's still important to stick to your recommended diet and exercise plan.

When medication is used

Orlistat is usually only recommended if you've made a significant effort to lose weight through diet, exercise or changing your lifestyle.

Even then, orlistat is only prescribed if you have:

  • a body mass index (BMI) of 28 or more and other conditions related to weight, such as high blood pressure
  • a BMI of 30 or more

Before prescribing orlistat, your doctor will discuss the benefits and potential limitations with you, including the side effects you may experience (see below). 

Treatment with orlistat must be combined with a low-fat diet and other weight loss strategies, such as doing more exercise. If you're prescribed orlistat, you'll also be offered advice and support about diet, exercise and making lifestyle changes.

Orlistat isn't usually recommended for pregnant or breastfeeding women.

Dosage and duration of treatment

One orlistat capsule is taken with each main meal (up to a maximum of three capsules a day). You can take the capsule either before, during or up to one hour after each meal.

If you miss a meal or the meal doesn't contain any fat, you may not need to take the orlistat capsule. Your GP should explain this to you, or you can check the patient information leaflet that comes with your medication.

Treatment with orlistat should only continue beyond three months if you've lost 5% of your body weight. It usually starts to affect how you digest fat within one to two days. If orlistat hasn't worked after three months, it's unlikely to be an effective treatment for you.

If you have type 2 diabetes, it may take you longer to lose weight using orlistat, so your target weight loss after three months may therefore be slightly lower.

If orlistat is successful after three months, your prescription may be continued for up to a year. After that, your GP will carry out a review and decide whether you should continue with orlistat.

Side effects

Common side effects of orlistat include:

These side effects are much less likely to occur if you stick to a low-fat diet.

Women taking the oral contraceptive pill are advised to use an additional method of contraception, such as a condom, if they experience severe diarrhoea while taking orlistat. This is because the contraceptive pill may not be absorbed by your body if you have diarrhoea, so it may not be effective.


Weight loss surgery, also called bariatric surgery, is sometimes used to treat people who are severely obese.

This type of surgery is usually only available on the NHS to treat people with severe obesity who haven't responded to other measures.

Severe obesity is defined as:

  • having a body mass index (BMI) of 40 or above
  • having a BMI of 35 or above and having another serious health condition that could be improved if you lose weight, such as type 2 diabetes, obstructive sleep apnoea or high blood pressure

In rare cases, surgery may be recommended as the first treatment (instead of lifestyle treatments and medication) if a person's BMI is 50 or above.

Treating obesity in children

Treating obesity in children is based on much the same principles as treating obesity in adults  by combining a calorie-controlled diet with regular exercise.

The amount of calories your child should eat every day will depend on their age and height. Your GP should be able to advise you about a recommended daily limit.

Children should ideally get at least 60 minutes (one hour) of moderate or greater intensity exercise a day, such as running or playing football or netball. The activity can be one 60 minute session or several sessions lasting 10 minutes or more. Children who are already overweight may need to do more than 60 minutes of exercise a day.

You should restrict sedentary activities, such as watching television or playing computer games, to less than two hours a day (14 hours a week).

It's important to encourage your children to increase their levels of physical activity and to make sure they continue to exercise regularly. Even if they don't lose weight immediately, there are many other health benefits that can be gained from regular exercise, such as a reduced risk of developing type 2 diabetes and cardiovascular disease.

Your child may be referred to a specialist in treating childhood obesity if they develop an obesity-related complication, have a learning difficulty, or if an underlying medical condition is thought to be causing the obesity. The treatment and support your child will be offered will depend on their specific needs and requirements.

The use of medication to treat obesity in children isn't usually recommended for children younger than 12 years. Orlistat is only recommended for use in children in exceptional circumstances – for example, if a child is severely obese and has an obesity-related complication, such as a problem with their bones or joints or sleep apnoea.

In cases where orlistat is prescribed to treat a child with obesity, the child will be closely monitored by a specialist paediatrician with experience in treating children with the medication and who is working as part of a multidisciplinary team.

Surgery isn't usually recommended for treating children or young people with obesity unless there are exceptional circumstances, such as if a child is severely obese and, as a result, has serious obesity-related complications.

Further information:

For more information on diet and exercise in children, see:

Page last reviewed: 04/03/2016

Next review due: 04/03/2018