If you are obese, speak to your GP for advice about losing weight safely.
Your GP can advise you on the type of diet you should be following and how you can much exercise you should do.
They can also let you know about other services, 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 are 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 pressure, diabetes 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 is no single rule that applies to everybody, most obese 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.
A healthy diet should consist of:
- plenty of fruit and vegetables
- plenty of potatoes, bread, rice, pasta and other starchy foods (ideally you should choose wholegrain varieties)
- some milk and dairy foods
- some meat, fish, eggs, beans and other non-dairy sources of protein
- just small amounts of food and drinks that are high in fat and sugar
Try to avoid foods containing high levels of salt as these can raise your blood pressure, which can be dangerous in people who are already obese. Read some tips for a lower-salt diet.
You will also need to check calorie information for each type of food and drink you consume, to make sure you do not go over your daily limit.
Some restaurants, cafés and fast food outlets provide calorie information per portion, but providing this information is not 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
You should 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 can make you feel ill and are not sustainable, because they don’t teach you long-term healthy eating habits.
This is not 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
A very low calorie diet (VLCD) is where you consume less than 1,000 calories a day.
These diets can lead to rapid weight loss, but they are not a suitable or safe method for everyone. VLCDs are usually only recommended if you have an obesity-related complication that would benefit from rapid weight loss, such as severe sleep apnoea.
VLCDs should usually not be followed for any longer than 12 weeks at a time, and they should only be adopted under the supervision of a suitably qualified healthcare professional.
For more information on 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 off the weight, you have to combine a calorie-controlled diet with regular exercise.
Your GP or weight loss adviser can provide an exercise plan suited 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:
- fast walking
- using a step-trainer (or similar) at the gym
Choose physical activities that you enjoy, as you are 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 of moderate-intensity exercise every week. However, if you are 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.
For more information on 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 more slowly and being mindful of what and when you are eating (for example, not being distracted by watching TV)
- avoiding situations where you know you may be tempted to overeat
- involving your friends and family with your weight loss efforts, as they can motivate you
- monitoring your progress – for example, weigh yourself regularly and note 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 is not absorbed into your body and is passed out with your faeces (stools).
This will help you avoid gaining weight, but will not 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 have 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
Treatment with orlistat must be combined with a low-fat diet and other weight loss strategies, such as doing more exercise. If you are prescribed orlistat, you will also be offered advice and support about diet, exercise and making lifestyle changes.
Orlistat is not 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 does not 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 have lost 5% of your body weight. It usually starts to affect how you digest fat within one to two days. If orlistat has not worked after three months, it is 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 review your condition and decide whether you should continue with orlistat.
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 that have not 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 if your BMI is 50 or above.
Read more about weight loss surgery.
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 advise a recommended daily limit.
Children should ideally get at least one hour of moderately-intense exercise a day, such as running, playing football or netball.
You should restrict sedentary activities, such as watching television or playing computer games, to less than two hours a day (14 hours a week).
Referral to a specialist in treating childhood obesity may be recommended if your child develops an obesity-related complication, or there is thought to be an underlying medical condition causing the obesity.
The use of orlistat in children is only recommended in exceptional circumstances – for example, if a child is severely obese and has an obesity-related complication.
For more information on diet and exercise in children, see:
Page last reviewed: 03/06/2014
Next review due: 03/06/2016