Intended for healthcare professionals

Practice Guidelines

Management of obesity: summary of SIGN guideline

BMJ 2010; 340 doi: (Published 24 February 2010) Cite this as: BMJ 2010;340:c154

This article has a correction. Please see:

  1. Jennifer Logue, clinical lecturer in metabolic medicine 1,
  2. Lorna Thompson, programme manager 2,
  3. Finn Romanes, consultant in public heath3,
  4. David C Wilson, reader in paediatric gastroenterology and nutrition4,
  5. Joyce Thompson, dietetic consultant in public health nutrition3,
  6. Naveed Sattar, professor of metabolic medicine1
  7. on behalf of the Guideline Development Group
  1. 1Division of Cardiovascular and Medical Sciences, Faculty of Medicine, University of Glasgow, Glasgow G12 8TA
  2. 2Scottish Intercollegiate Guidelines Network (SIGN), Edinburgh EH7 5EA
  3. 3Directorate of Public Health, NHS Tayside, Dundee DD3 8EA
  4. 4Child Life and Health, University of Edinburgh, Edinburgh EH9 1UW
  1. Correspondence to: J Logue j.logue{at}

    Why read this summary?

    In Scotland 68.5% of men, 61.8% of women, 36.1% of boys, and 26.9% of girls are classified as overweight or obese.1 The cost of obesity and obesity related illnesses to the NHS in Scotland was estimated to be £171m (€190m; $273m) in 2001,2 and forecasts in England suggest that NHS expenditure attributable to these conditions could double between 2007 and 2050.3 Being obese at age 40 reduces life expectancy by 7.1 years for women and 5.8 years for men.4 Given the massive detrimental effect of obesity on health and wellbeing, all health professionals should know how obesity should be managed. This article summarises the most recent recommendations from the Scottish Intercollegiate Guidelines Network (SIGN) on the management of obesity.5


    SIGN recommendations are based on systematic reviews of best available evidence, and the strength of the evidence is indicated as A, B, C, or D (figure). Recommended best practice (“good practice points”), based on the clinical experience of the guideline development group, is also indicated (as GPP).


    Explanation of SIGN grades of recommendations

    Obesity and overweight in adults


    Use body mass index (BMI) to classify overweight or obesity in adults (B):

    • Less than 18.5—underweight.

    • 18.5-24.9—normal range.

    • 25-29.9—overweight.

    • 30-34.9—obesity I.

    • 35-39.9—obesity II.

    • 40 or more—obesity III.6

    Waist circumference may be used in addition to BMI to help assess the risk of obesity related comorbidities (C). Waist circumference cut-off values for an increased risk of obesity related health problems are:

    • Women: 80 cm or more.

    • Men: 94 cm (Asian men 90 cm) or more.6 7

    Prevention and identification of high risk groups

    • Help prevent obesity by emphasising healthy eating ( (GPP), encouraging physical activity, and reducing sedentary behaviour (B).

    • Encourage patients to weigh themselves (B).

    • Be aware that patients at higher risk of obesity include those planning to stop smoking and those prescribed drugs that are associated with weight gain (C). Offer interventions for managing weight to patients in these groups (B).


    • Seek a weight history, including previous attempts to lose weight (GPP).

    • Discuss willingness to change with patients, and target weight loss interventions according to their willingness around each behavioural component required for weight loss ( (D).

    • Beware of the possibility of binge eating disorder in patients who have difficulty losing weight and maintaining weight loss (C).

    • Advise patients of the following health benefits associated with sustained modest weight loss:

      • - Improved lipid profiles (A), improved glycaemic control (B), and reduced blood pressure (B).

      • - Lower risk of type 2 diabetes (B).

      • - Lower mortality from cancer, diabetes, and all causes in some patient groups (B).

      • - Lower osteoarthritis related disability (A).

      • - Improved lung function in patients with asthma (B).


    Treatment targets

    Base weight loss targets on comorbidities and risks, rather than on weight alone:

    • Patients with a BMI over 35 are likely to have obesity related comorbidities, and weight loss interventions should aim to improve these comorbidities. Many will need to lose more than 15-20% of their weight (over 10 kg) for a sustained improvement in comorbidities (GPP).

    • Patients with a BMI of 25-35 are less likely to have obesity related comorbidities, and a 5-10% weight loss (around 5-10 kg) is needed to reduce the risk of cardiovascular and metabolic disease (GPP).

    • Patients from certain ethnic groups (for example, South Asians) are more susceptible to the metabolic effects of obesity, and related comorbidities are likely to occur at lower BMI cut-off points; tailor thresholds to individual needs (GPP).

    When evaluating the success of any intervention, include a measurement of improvement in comorbidities as well as absolute weight loss (GPP).

    Weight management programmes

    • These should include dietary change, physical activity, and behavioural components (A).

    • Consider evidence based weight management programmes delivered through the internet as part of a range of options (B).

    • Do not offer clinical weight loss interventions without considering the patient’s willingness to make long term changes or providing support for maintaining the weight loss (C).

    Dietary interventions

    • Calculate dietary interventions for weight loss to produce a 2.5 MJ (600 kcal) energy deficit each day and tailor these to the patient’s dietary preferences (A).

    • When discussing dietary change with patients, emphasise achievable and sustainable healthy eating (GPP). This includes reducing the intake of energy dense foods (including foods containing animal fats, other high fat foods, confectionary, and sugary drinks) by selecting foods with a low energy density instead (such as wholegrain foods, cereals, fruit, vegetables, and salads) and reducing consumption of “fast foods” and alcohol (B).

    Physical activity

    For overweight and obese people, prescribe a volume of physical activity equal to 7.5-10.45 MJ (1800-2500 kcal) a week. This corresponds to 225-300 minutes a week of moderate intensity physical activity (for example, five sessions of 45-60 minutes a week) (B).

    • Such activity increases the rate of breathing and body temperature, but at a pace that still allows comfortable conversation (GPP).

    • For obese people this can often be achieved though brisk walking (GPP).

    • Physical activity can be accumulated over the course of the day in several small sessions of at least 10 minutes’ duration (GPP)

    • Sedentary people should build up their physical activity targets over several weeks (GPP).

    Behavioural interventions

    Target psychological and behavioural interventions to the individual and their circumstances (GPP).

    Psychological and behavioural treatments include:

    • Situational control including avoidance of cues to unhealthy eating.

    • Self monitoring of food intake.

    • Goal setting that includes relapse prevention strategies.

    • Cognitive strategies to replace negative thinking with more positive statements.


    Consider orlistat as an adjunct to lifestyle interventions (A), but only where diet, physical activity, and behavioural changes are supported (GPP).

    Bariatric surgery

    Include this as part of the overall clinical plan for adults (GPP). Consider this after individual assessment of risk-benefit in patients with all three of the following:

    • BMI of 35 or more (C).

    • One or more severe comorbidities that are expected to have a meaningful clinical improvement with weight reduction (for example, severe mobility problems, arthritis, type 2 diabetes) (C).

    • Evidence of completion of a structured weight management programme that covered diet, physical activity, and psychological and drug interventions but did not result in significant and sustained improvement in comorbidities (GPP).

    Seek specialist psychological or psychiatric opinion as to which patients require assessment or treatment before or after surgery (GPP). Binge eating disorder, dysfunctional eating behaviour, history of intervention for substance misuse, psychological dysfunction, and depression are not absolute contraindications for surgery (C).

    Obesity in children and young people


    • Overweight: BMI ≥91st centile (GPP).

    • Obese: BMI ≥98th centile (D).

    • Severe obesity: BMI ≥99.6th centile (GPP).

    • Very severe obesity: BMI >3.5 standard deviations above the mean (GPP).

    • Extreme obesity: BMI >4 standard deviations above the mean (GPP).8


    The principles for preventing obesity in adults are equally relevant for children and young people. Although preventive measures will probably require a broad range of interventions across all settings, most studies have been conducted in schools. School based interventions should be considered across all planners and providers of services. Actively facilitate involvement of the parents and family (C).


    Lifestyle interventions should be family based, involving at least one parent or carer, and should encourage behaviour changes that aim to change the whole family’s lifestyle (B).

    Weight loss and maintenance can be achieved only by sustained behavioural changes, such as:

    • Eating more healthily and decreasing energy intake.

    • Increasing habitual physical activity (60 minutes of moderate to vigorous physical activity each day)

    • Reducing sedentary behaviour (such as watching television) to less than two hours each day (D).

    For overweight and most obese children, weight maintenance is an acceptable goal (D).

    Annual monitoring of the child’s BMI centile may be appropriate to reinforce weight maintenance (D).

    For children with a BMI on or above the 99.6th centile, gradual weight loss to a maximum of 0.5-1.0 kg each month is acceptable (D).

    Refer to hospital or specialist paediatric services before starting treatment if either of the following applies:

    • The child may have a serious obesity related morbidity that needs treatment.

    • An underlying medical cause is suspected (this should include all children under 24 months who have severe obesity) (D).

    Prescribe orlistat only for severely obese adolescents with comorbidities, or adolescents with very severe or extreme obesity; they should be attending a specialist clinic with regular reviews and monitoring for side effects (D).

    Consider bariatric surgery for postpubertal adolescents with very severe to extreme obesity and severe comorbidity (D).

    Overcoming barriers

    The scale of the obesity epidemic makes it difficult to manage every overweight and obese person through clinical services; social and environmental changes, food education, and community based interventions are needed. However, all health professionals should be able to recognise obesity and its related comorbidities and access resources to manage obesity. Currently, obesity is poorly recognised and documented.9 Clinicians do not feel they have expertise, or access to expertise, in weight management,10 and some doubt whether it is within their remit.11 In paediatrics, lack of time, lack of training, and the poor motivation of patients were seen as major barriers to tackling childhood obesity in a clinical setting.12

    Management of obesity cannot remain the domain of a few individuals with a specialist interest. All health professionals should receive appropriate training, from undergraduate level onward, along with information about local resources. For obesity to be given the priority it deserves in clinical services, negative attitudes towards this condition and its causes must be checked. We need to move from blaming the individual towards treating this modifiable cause of severe ill health and premature mortality.13

    Further information on the guidance


    The development of the guideline followed established SIGN methodology based on a systematic review of the evidence. SIGN is a collaborative network of clinicians, other healthcare professionals, and patient organisations and is part of NHS Quality Improvement Scotland. Further details about SIGN and the guideline development methodology are contained in SIGN 50: A Guideline Developer’s Handbook (see

    The National Institute for Health and Clinical Excellence (NICE) published a comprehensive obesity guideline for England and Wales in December 2006.14 To avoid duplication of effort SIGN used and updated evidence tables produced by NICE, where appropriate, as a basis for considered judgment. The ADAPTE process for guideline adaptation was followed.15

    Future research and remaining uncertainties

    The guideline development group was not able to identify sufficient evidence to answer all the key questions asked in this guideline. Areas identified for further research include:

    • Assessment of interventions to support maintenance of weight loss

    • Identification of the most effective way to deliver dietary advice

    • Identification of the effectiveness of customised weight management training for professionals to determine the approach and resources most likely to improve outcomes for patients

    • Consideration of which patient groups have the greatest long term benefits from bariatric surgery in terms of reduction of future comorbidities and mortality

    • Large well designed research studies (following the CONSORT principles) in the prevention of childhood obesity are needed in the United Kingdom

    • Identification of the reduction in fatness needed in children (expressed as simple clinical measures, such as change in BMI standard deviation score) to reduce obesity related comorbidities


    Cite this as: BMJ 2010;340:c154


    • This is one of a series of BMJ summaries of new guidelines, which are based on the best available evidence; they highlight important recommendations for clinical practice, especially where uncertainty or controversy exists.

    • The members of the Guideline Development Group are Joyce Thompson (co-chair), dietetic consultant in public health nutrition, NHS Tayside, Dundee; David Wilson (co-chair), reader in paediatric gastroenterology and nutrition, University of Edinburgh; Satinder Bal, consultant in endocrinology, Raigmore Hospital, Inverness; Ewan Bell, consultant clinical biochemist, Dumfries and Galloway Royal Infirmary; Susan Boyle, consultant clinical psychologist, Glasgow and Clyde Weight Management Service; Duff Bruce, consultant surgeon, Aberdeen Royal Infirmary; Fiona Clarke, senior health promotion specialist, NHS Highland, Inverness; Kim Ferrier, physiotherapist, Glasgow and Clyde Weight Management Service; Lorna Forde, service lead, Glasgow and Clyde Weight Management Service; Jason Gill, senior lecturer in exercise science, Glasgow University; Gail Haddock, general practitioner, Cromarty; Catherine Hankey, senior lecturer in human nutrition, Glasgow University; Rosaleen Isles, cognitive therapist, Dumfries and Galloway Royal Infirmary; Susan Kayes, public health nurse, Cathkin High School, Glasgow; Joanna Kelly, information officer, SIGN; Jennifer Logue, clinical lecturer in metabolic medicine, Glasgow University; Kevin McConville, general practitioner, Buckhaven; Pamela McIntosh, advanced specialist dietitian, Stirling; Aileen Muir, consultant in pharmaceutical public health, NHS Lothian; John Reilly, head of childhood obesity group, Queen Mother’s Hospital, Glasgow; Finn Romanes, consultant in public health medicine (health protection), NHS Tayside; Naveed Sattar, professor of metabolic medicine, Glasgow University; Laura Stewart, team lead, Paediatric Obesity Service, NHS Tayside; Mae Stewart, lay representative, Dundee; Lorna Thompson, programme manager, SIGN; Elizabeth White, health visitor and public health team leader, Oban and Lorn Medical Centre, Oban.

    • Contributors: JL and NS drafted the article. All authors were involved in the conception, design, and interpretation of data and the revision and final approval of the article.

    • Funding: No funding was received for writing this summary.

    • All authors have completed the Unified Competing Interest form at (available on request from the corresponding author) and declare that (1) they have not received support for the submitted work; (2) JL and NS have received research funding from Allergan UK, but DCW, LT, FR, and JT have no relationships with companies that might have an interest in the submitted work in the previous 3 years; (3) their spouses, partners, or children have no financial relationships that may be relevant to the submitted work; and (4) they have no non-financial interests that may be relevant to the submitted work.

    • Provenance and peer review: Commissioned; not externally peer reviewed.