Dr Kevin McConville outlines the SIGN recommendations on the classification, prevention, and treatment of overweight and obesity in adults and children

Recently published data from the Scottish Government suggest that by 2030 the total cost to Scottish society of obesity (direct and indirect costs) could range from £0.9 billion to £3 billion.1 This highlights the burden of obesity on the healthcare system. In response to the problem of obesity, SIGN published its clinical guideline on the Management of obesity.2 This document updates and supersedes the previous SIGN guidelines on obesity in adults (SIGN 8, 1996) and obesity in children and young people (SIGN 69, 2003).3,4

Although, the SIGN guideline focuses on treating affected individuals with elevated health risks, it acknowledges that this represents only one aspect of a wider societal solution.2 The need for a comprehensive and multisectorial approach to prevention of obesity is highlighted.

As with all SIGN guidelines, each recommendation is accompanied with a grade relating to the strength of the supporting evidence on which the recommendation is based. In this article, these grades, along with good practice points (GPP), appear in brackets after recommendations. The key to evidence statements and grades of recommendations can be found in the guideline.2

Obesity and overweight in adults

A suggested care pathway for adults with overweight and obesity is shown in Figure 1.

Body mass index (BMI) should be used to classify adults who are overweight or obese (Grade B) (see Table 1). In addition to BMI, waist circumference may be used to refine risk assessment of obesity-related co-morbidities
(Grade C).2

Prevention of overweight and obesity in adults
Two key factors in the prevention of weight problems are diet and exercise. Healthcare professionals should emphasise healthy eating;2 the eatwell plate is the nationally recognised model5 and GPs can access more information through its website (www.eatwell.gov.uk). The SIGN guideline also provides further information on a healthy lifestyle.2

Regardless of BMI, patients consulting about weight management should be encouraged to (Grade B):2

  • be physically active
  • reduce sedentary behaviour, including time spent watching television
  • undertake regular self weighing.

Healthcare professionals should make patients aware of the health benefits that are associated with sustained modest weight loss:

  • Improved lipid profiles (Grade A)
  • Reduced osteoarthritis-related disability (Grade A)
  • Lowered all-cause, cancer, and diabetes mortality in some patient groups (Grade B)
  • Reduced blood pressure (Grade B)
  • Improved glycaemic control (Grade B)
  • Reduction in risk of type 2 diabetes (Grade B)
  • Potential for improved lung function in patients with asthma (Grade B).

As part of identifying high-risk groups in adults, healthcare professionals should discuss weight management measures with patients who are planning to stop smoking or who are prescribed medications associated with weight gain (Grade B).2 Patients should be advised that the use of combined contraceptives or hormone replacement therapy is not associated with significant weight gain (Grade B).2

Co-morbidities, risk factors, and weight history, including previous weight-loss attempts, should be included during clinical assessment (GPP). Liver function tests should be considered in patients who are obese (GPP).2

It is important for healthcare professionals to assess a patient’s motivation for behaviour change. Weight-loss interventions should be targeted according to patient willingness around each component of behaviour required for weight loss (e.g. specific dietary and/or activity changes) (Grade D). The Healthy Living Readiness Ruler has been suggested as a way of identifying patient readiness.6

Healthcare professionals should be aware of the possibility of binge eating disorder in patients who have difficulty losing weight and maintaining weight loss (Grade C).2

The SIGN guideline recommends that targets for weight loss should be based on the individual’s co-morbidities and risks, and not on their weight alone:2

  • In patients with a BMI of 25–35 kg/m2, obesity-related co-morbidities are less likely to be present and a 5%–10% weight loss (approximately 5–10 kg) is required for cardiovascular disease and metabolic risk reduction (GPP)
  • In patients with a BMI >35 kg/m2, obesity-related co-morbidities are likely to be present, therefore interventions for weight loss should be targeted to improving these co-morbidities; in many individuals a greater than 15%–20% weight loss (which will always be over 10 kg) will be required to obtain a sustained improvement in co-morbidity (GPP).

Weight-management programmes should include physical activity, dietary change, and behavioural components (Grade A). It may be useful for the GP to consider using the internet as a method of delivering an evidence-based weight management programme (e.g. www.takelifeon.co.uk) (Grade B).2

A sustainable modest weight loss can be achieved though dietary interventions that result in a 600 kcal/day energy deficit (Grade A). Programmes should be tailored to the dietary preferences of the individual patient, with an emphasis on achieving and maintaining healthy eating (GPP).2

The British Dietetic Association specialist group on obesity management has produced a position statement on the use of very low energy diets, which requires close medical and dietary supervision.7 Where very low calorie diets are indicated for rapid weight loss, these should be conducted under medical supervision (Grade D).2

Multicomponent weight-management programmes for individuals who are overweight or obese should include increased physical activity (Grade A).2 However, it is important to ensure that individuals have no contraindications to exercise before commencing a physical activity programme (GPP). The physical activity readiness questionnaire (PAR-Q) should be used to determine if it is safe for the patient to participate in increased physical activity (GPP).2

To help patients achieve weight loss, clear and realistic goals should be set, and they should also be made aware of the health benefits associated with an active lifestyle (GPP).2 Adults who are overweight and obese should be prescribed a volume of physical activity equivalent to approximately 1800–2500 kcal/week. This corresponds to approximately 225–300 min/week of moderate intensity physical activity (which may be achieved through five sessions of 45–60 minutes per week, or lesser amounts of vigorous activity) (Grade B). Moderate physical activity is defined as any activity that increases the rate of breathing and body temperature. In patients who are obese, this can include brisk walking (walking at a faster than normal pace).2

Psychological interventions
Psychological interventions (e.g. self monitoring of behaviour, stimulus control), either individual or group based, should form part of weight-management programmes (Grade A).2

Pharmacological management
Orlistat should be considered as an adjunct to lifestyle interventions. Patients with a BMI ?28 kg/m2 (with co-morbidities) or a BMI ?30 kg/m2 should be considered for treatment on an individual patient basis following assessment of risk and benefit (Grade A).2

Bariatric surgery should be included as part of an overall clinical pathway for adult weight management (GPP). Specialist psychological/psychiatrist opinion should be sought before surgery. Bariatric surgery should be considered on an individual patient basis following assessment of risk/benefit in patients who fulfil any of the following three criteria:2

  • a BMI ?35 kg/m2 (Grade C)
  • one or more severe co-morbidities that are expected to improve significantly with weight reduction (e.g. severe mobility problems, arthritis, type 2 diabetes) (Grade C)
  • evidence of completion of a structured weight management programme involving diet, physical activity, and psychological and drug interventions, not resulting in significant and sustained improvement in co-morbidities (GPP).
Figure 1: Suggested primary care pathway for adults with overweight and obesity2


*South Asian, Chinese, and Japanese individuals may be considered overweight at BMI >23 kg/m2 and obese at BMI >27.5 kg/m2
BMI=body mass index
Scottish Intercollegiate Guidelines Network. Management of obesity. A national clinical guideline. SIGN 115. Edinburgh: SIGN; 2010. Reproduced with kind permission of the Scottish Intercollegiate Guidelines Network

Table 1: Body mass index thresholds in adults2
Body mass index (kg/m2) Definition
<18.5 Underweight
18.5–24.9 Normal range
25–29.9 Overweight
30–34.9 Obesity I
35–39.9 Obesity II
?40 Obesity III


Obesity and overweight in children

Examination of the literature covered in the SIGN guideline defined children and young people as being <18 years of age, although most of the evidence identified related to children of primary school age. Obesity in children is different to obesity in adults in some important respects: the main difference is that all children and adolescents need to grow—during puberty a child’s height will double and their weight will increase by 20%. When considering the prevention and treatment of childhood obesity, dietary energy restriction, increase in activity, and a decrease in sedentary behaviour must not compromise normal growth and development. For these reasons, weight maintenance is often a suitable goal rather than weight loss.

A suggested care pathway for children and young people with overweight and obesity is shown in Figure 2.

Body mass index centiles should be used to diagnose overweight and obesity in children (Grade C):2

  • Overweight—BMI ?91st centile (GPP)
  • Obese—BMI ?98th centile (Grade D)
  • Severe obesity—BMI ?99.6th centile (GPP).

Although preventive measures for child obesity are likely to require a broad range of interventions across all settings, most studies have been performed in the school environment. The SIGN recommendation for prevention of obesity is based largely on the school-based ‘Planet Health’ intervention:8

  • Sustainable school-based interventions to prevent overweight and obesity should be considered by and across agencies. Parental and family involvement should be actively facilitated (Grade C).2

Treatment programmes for managing obesity in children should include behaviour change and involve at least one parent/carer and aim to change the whole family’s lifestyle (Grade B). Weight maintenance and/or weight loss can only be achieved by sustained behavioural changes, such as (Grade D):2

  • healthier eating and decreased total energy intake
  • increasing habitual physical activity—60 minutes of moderate-vigorous activity/day is recommended for healthy children
  • reducing time spent in sedentary behaviour to <2 hours/day on average.

In most children who are obese (BMI ?98th centile) weight maintenance is an acceptable treatment goal (Grade D).2

Referral to hospital or specialist paediatric services should take place before treatment is considered if (Grade D):2

  • the child has serious obesity-related morbidity that requires weight loss (e.g. sleep apnoea, orthopaedic problems, or psychological morbidity)
  • an underlying medical condition (e.g. endocrine) is suspected; this includes all children under 24 months of age who are severely obese (BMI ?99.6th centile).

Pharmacological and surgical interventions
Orlistat should only be prescribed for adolescents who are severely obese with co-morbidities, or individuals with very severe to extreme obesity (Grade D).2 Bariatric surgery can be considered as a treatment option for post-pubertal adolescents with very severe to extreme obesity and severe co-morbidities (Grade D).2

Figure 2: Suggested primary care pathway for children and young people with overweight and obesity2


BMI=body mass index
Scottish Intercollegiate Guidelines Network. Management of obesity. A national clinical guideline. SIGN 115. Edinburgh: SIGN; 2010. Reproduced with kind permission of the Scottish Intercollegiate Guidelines Network

Role of primary care

The National Obesity Forum has succinctly identified the challenges and strategies faced by primary care in dealing with obesity management. It has suggested five main reasons for primary care involvement:9

  • The recognition that obesity is a serious medical condition has increased
  • The Government is concerned with the increasing levels of obesity
  • General practice is where most people, obese or not, come into contact with medical services
  • The rising levels of obesity will impact on other areas of healthcare provision
  • The increasing prevalence of obesity in children is of grave concern.

It is important to provide information to both patients and parents/carers of patients on achieving and maintaining a healthy lifestyle. The National Obesity Forum website and Chapter 20 of the SIGN guideline provide information and resources to help implement effective management strategies in dealing with this growing problem.


Obesity is a complex condition and it is not surprising that many healthcare professionals feel daunted about tackling the problem. Time restrictions and the lack of suitable resources underlie the concerns that some healthcare professionals express with regard to treating obesity. Other individuals highlight that inadequate training, skills, and support undermine their confidence in dealing with patients who are obese.9 Clinicians have often expressed their fears of ‘medicalising’ a social problem.

From the outset, the SIGN guideline, clearly identifies that there is a need for a comprehensive and multi-sectorial approach to obesity prevention, which requires interaction with commercial, environmental, and social policy drivers of obesity. However, it has provided clear and evidence-based guidance to assist on prevention and treatment within the clinical setting. Most importantly is our need to retain a positive and enthusiastic approach to effect change and empower the patient to take responsibility for their health.

Key Points
  • BMI should be used to classify adults who are overweight or obese
  • BMI centiles should be used to diagnose overweight and obesity in children
  • Weight management programmes should include physical activity, dietary change, and behavioural components
  • Clear and realistic physical activity goals should be set
  • Programmes should be tailored to the dietary preferences of the individual patient
  • Orlistat should be considered as an adjunct to lifestyle interventions
  • Bariatric surgery should be considered on an individual case basis following assessment of risk/benefit in patients who fulfil the appropriate criteria

BMI=body mass index

  • Obesity is a potent cause of longer-term morbidity and health expenditure
  • Dietary intervention, promotion of exercise, and behavioural modification are the key effective interventions
  • Interventions should be targeted at those willing to embrace change and/or those with co-morbidities
  • Locally commissioned weight-management intervention services should include all these dynamics and be responsive to patient choice
  • BMI remains an effective measure of obesity but certain Asian populations are more prone to co-morbidities at lower values
  • Orlistat and bariatric surgery are effective interventions, but their role should be specified in local care pathways informed by SIGN and NICE guidance
  • Orlistat costs (120 mg tds) £31.63 per montha
  • Bariatric surgery has no national mandatory tariff

BMI=body mass index

  1. The Scottish Government. Preventing overweight and obesity in Scotland. A route map towards healthy weight. Edinburgh: The Scottish Government, 2010. Available at: www.scotland.gov.uk/Publications/2010/02/17140721/19
  2. Scottish Intercollegiate Guidelines Network. Management of obesity. SIGN 115. Edinburgh: SIGN, 2010. Available at: www.sign.ac.uk/guidelines/fulltext/115/index.html
  3. Scottish Intercollegiate Guidelines Network. Obesity in Scotland: integrating prevention with weight management. SIGN 8. Edinburgh: SIGN, 1996.
  4. Scottish Intercollegiate Guidelines Network. Management of obesity in children and young people. SIGN 69. Edinburgh: SIGN, 2003.
  5. Food Standards Agency. Eatwell. www.eatwell.gov.uk (accessed 29 April 2010).
  6. NHS Health Scotland. Towards healthy living—Readiness ruler. www.healthscotland.com/uploads/documents/2976-Healthy_Living_Readiness_Ruler_2_pages.pdf
  7. Dieticians in Obesity Management UK. Position statement on very low energy diets in the management of obesity. Middlesbrough: DOM UK, 2007. Available at: domuk.org/wp-content/uploads/2007/02/very-low-energy-diets.pdf
  8. Gortmaker S, Peterson K, Weich J et al. Reducing obesity via a school based interdisciplinary intervention among youth: Planet Health. Arch Pediatr Adolesc Med 1999; 153 (4): 409–418.
  9. The National Obesity Forum website. The role of primary care. www.nationalobesityforum.org.uk/healthcare-professionals-mainmenu-155/the-role-of-primary-care- mainmenu-164/134-introduction.html (accessed 29 April 2010). G