Managing overweight and obesity in children and adolescents

This page has been written by Hiba Jebeile and Professor Louise Baur; and reviewed by Professor Kate Steinbeck and Dr Shirley Alexander.

While prevention is key to ending overweight and obesity in the long term, effective treatment, including weight management, during childhood and adolescence is also vital. It helps to address current and future risk and complications as well as the risk of overweight and obesity persisting into adulthood. Compared to adults, the diagnosis and monitoring of overweight and obesity during childhood and adolescence can be challenging due to the rapid growth and development occurring at this time. Body composition also varies by age, sex and stage of growth for example, pubertal status, so single cut-points cannot be used to define overweight and obesity status.

Assessment

Routine assessment of child growth should be part of standard paediatric clinical practice. When done routinely, abnormal growth patterns are easier to recognise.¹ There are various ways of diagnosing overweight and obesity, as discussed below.

1. Body mass index (BMI) is a measure of weight adjusted for height, calculated as weight (kg)/height (m)². It is the preferred simple screening measure to determine overweight and obesity in children and adolescents. For children, BMI should be plotted on age and sex specific BMI growth charts, such as those from the United States Centers for Disease Control and Prevention (US-CDC) or the World Health Organization.

Classification of weight status based in this case on the US-CDC growth charts is listed in the following table.²

2. BMI as a standard deviation score or z-score is used to calculate how far a child’s BMI is above or below the mean (a z-score of 0 is the same as a 50th percentile). It can provide a more accurate representation of change over time than using BMI percentiles alone, particularly for children and adolescents with overweight or obesity.

For children and adolescents with severe obesity, BMI expressed relative to the 95th percentile (BMI%95 percentile) is recommended. For example, a child with a BMI%95 percentile of 150 would have a BMI equivalent to 1.5 times the 95th percentile.

3. A waist to height ratio (waist circumference divided by height) of greater than 0.5 is a useful indicator of central adiposity and is predictive of cardiovascular risk in school-aged children and adolescents.³

A thorough clinical history is central to the assess­ment of a child’s or adolescent’s current and poten­tial future health complications, as well as for assessing their modifiable lifestyle practices. Assessment of psychological and social health should be included because children and young people with obesity especially are at increased risk of a range of associated health problems, including poor self-esteem, depression and disordered eating.

Clinical investigations of potential obesity-associated complications are appropriate in most adolescents with obesity, and in all patients with severe obesity, with clinical signs or history suggestive of complications, or with a family history risk of type 2 diabetes or heart disease. Investigations normally include liver function tests and fasting glucose, lipids and possibly insulin levels. Assessment of micronutrient deficiencies should also be considered.¹⁴

Management approaches

The primary aims of weight management may include a change in weight-related outcomes such as BMI maintenance, reduction or an altered BMI trajectory. Other aims may include improvements in obesity-related complications and/or a reduction in markers relating to risk of future complications.⁵

The first-line approach for child and adolescent overweight and obesity involves behavioural modification to manage weight. In addition, particularly for post-pubertal adolescents with more severe obesity, there may be a need for intensive dietary approaches, anti-obesity pharmacotherapy and/or bariatric surgery in combination with lifestyle change.

Lifestyle intervention

Lifestyle intervention incorporates changes to diet, physical activity and sleep, underpinned by strategies to support behaviour change.

This approach to weight management has several overarching principles⁴ including:

• management of associated risks and complications
• family involvement
• a developmentally appropriate approach
• long-term behaviour modification:
  • dietary change
  • increased physical activity
  • reduced sedentary behaviours
  • improved sleep behaviours
• planning for longer-term weight maintenance.

Dietary counselling should focus on shifting dietary patterns to those that align with the Australian Guide to Healthy Eating, and may include dietary education alone or combined with an energy prescription. Principles of dietary education may include increased intake of fruit and vegetables, reductions in energy-dense nutrient-poor foods and sugar-sweetened beverages, and improved mealtime routines.

Recommendations for physical activity, sedentary behaviour and sleep should be in keeping with the Australian 24-Hour Movement Guidelines for Children and Young People. Addressing physical activity may include incorporating physical activity into daily routines, structured exercise programs, and encouraging active transport (e.g. walking or cycling to school). School-aged children and adolescents should incorporate 60 minutes or more of moderate to vigorous physical activity into their day as well as several hours per day of light activities. Recreational screen-time should be limited to less than two hours per day. Changes to improve sleep quality and duration may include modifying bedtime routines and reducing screen time in the evening.

Strategies to support behaviour change include goal setting using SMART goals (specific, measurable, achievable, realistic, time-bound); parental modelling of the desired behaviour; stimulus control (modifying the environment); and self-monitoring (food, activity or sleep diary).

Lifestyle interventions are effective at treating overweight and obesity in the short-term with few studies reporting on long-term outcomes. The most recent Cochrane reviews^{6 7} published in 2017 found lifestyle interventions to be beneficial for reducing weight, BMI and BMI z-score in children 6−11 years and adolescents 12−17 years with overweight or obesity. These reviews drew on studies that followed children for up to three years and adolescents for up to two years.

Lifestyle interventions also lead to improvements in physiological and psychological health. Total cholesterol, triglycerides (a type of fat found in blood) and measures of insulin resistance improve following lifestyle interventions.⁸ A reduced prevalence of obstructive sleep apnoea and increased sleep duration have also been reported.⁹ Similarly, improvements in psychological health have been seen for most participants, including reduced symptoms of depression and anxiety,¹⁰ improvements in body image, self-esteem¹¹ and quality of life¹² and reduced risk of developing eating disorders.¹³

Importantly, all of these improvements in physiological and psychological health relate to professionally administered programs delivered in a clinical setting or as clinical trials. Access to this type of high-level care in Australia is limited. Little is known about how young people may be managing obesity on their own. Observational data suggest that this is predominantly done through dieting with the intention of weight loss. These behaviours, when unsupervised, may be associated with further weight gain, disordered eating and symptoms of depression. This highlights the importance of increasing access to high quality care.

Intensive dietary approaches

Adolescents with obesity-related risks or complications or more severe obesity may benefit from more intensive dietary approaches. Very Low Energy Diets (VLEDs), consisting of a significantly reduced energy intake of approximately 800kcal/day, and often involving the use of nutritionally complete meal replacement supplements, are one such option. VLEDs are designed to induce ketosis and therefore suppress appetite. Children and adolescents experienced weight reduction in the short-term (up to 20 weeks), with greater weight loss in adolescents, with the use of formulated meal replacements in an inpatient setting.¹⁴ Restrictive diets such as these should only be prescribed for short-term use by experienced multidisciplinary teams.

Low-carbohydrate dietary approaches are re-emerging as as a popular method of weight reduction in adults. These typically include a carbohydrate restriction of 30−120g of carbohydrate per day. In children and adolescents, short-term (< 6 months) low-carbohydrate approaches may have a greater reduction in BMI and BMI z-score when compared to a low-fat intervention, but in the longer term they do not appear to have a more beneficial impact on weight than a standard reduced calorie approach.¹⁵ Low-carbohydrate diets may benefit young people with pre-diabetes or type 2 diabetes, insulin resistance or non-alcoholic fatty liver disease and research in these areas is underway.

Drug interventions

Official guidelines for use of pharmacotherapy to treat obesity in children and adolescents are not currently available in Australia. Pharmacotherapy may be prescribed in combination with lifestyle interventions if conventional approaches alone have been unsuccessful. Currently, the availability of anti-obesity agents is very limited, with many having only been trialled in adults. There are currently no single agent anti-obesity agents listed on the Pharmaceutical Benefits Scheme. Orlistat is available for use in adolescents in most jurisdictions in Australia and is associated with modest BMI reductions in adolescents. Orlistat has gastrointestinal side-effects including fatty/oily stool and faecal urgency which will cause non-adherence. Metformin (off-label indication) may also be prescribed in adolescents with insulin resistance and obesity, and may be associated with diarrhoea, mild abdominal pain or nausea.¹⁶ There are ongoing trials for pharmacologic agents used for other conditions which may have value in obesity management. These include glucagon-like peptide 1 (GLP1) agonists used in type 2 diabetes and topiramate used in treatment of epilepsy and migraine headaches.^{5 17} Phentermine remains on private script as an anti-obesity agent from 12 years of age. However, it is not used in children as it carries a risk of addiction. Experience in adults does not support its addictive potential.

Metabolic and bariatric surgery

Recommendations for use of metabolic and bariatric surgery to treat obesity in Australian adolescents suggest that surgery should be considered in adolescents older than 15 years, with severe obesity and/or with severe complications, and following at least six months of supervised lifestyle modification with/without pharmacotherapy. The adolescent must be able to provide informed consent and understand the operation, potential risks and the need for long-term follow-up.¹⁸ Surgical procedures including gastric banding, gastric sleeve, and gastric bypass have shown success in predominantly female adolescents with severe obesity. The mean (95% CI) BMI (kg/m²) change at 36 months post-surgery was −10.3 (−7.0, −13.7) after gastric band, −13.0 (−11.0, −15.0) after gastric sleeve, and −15.0 (−13.5, −16.5) after gastric bypass.¹⁹ It is important to note that current surgery techniques are associated with complications including the need for re-operation and risk of nutritional deficiencies.²⁰

In Australia, access to metabolic and bariatric surgery is very limited for adolescents, especially in the public system. A challenge for health care systems in Australia is how to ensure equitable access to appropriate bariatric surgery services for affected adolescents.¹

Resources

The NSW Government has developed resources to help health professionals manage children above a healthy weight on the Healthy kids for professionals website

These resources may be particularly useful:

• Videos showing how to raise the issue with families in a non-judgemental and supportive way
• Short, free training modules on aspects of child and adolescent obesity for health professionals
• Infographics on eight healthy habits for children and adolescents, available in different languages
• The Go4Fun community treatment program available as a face-to-face program in NSW and online