The prevalence and severity of childhood obesity has been increasing in recent years in Ireland and worldwide.¹ Currently in Ireland one in five children aged between five and 18 years is overweight or obese.^2,3 From 1990 to 2008, the incidence of obesity among the Irish teenage population increased from 1% to 8% in males and 3% to 6% in females.³ These trends are likely to be multifactorial including genetics, dietary intake, physical inactivity, and the environment.⁴

Childhood obesity is associated with a wide spectrum of co-morbid illnesses, from cardiovascular, respiratory and orthopaedic consequences in early life, to later endocrinological and oncological consequences. One of the major difficulties health services have had in tackling this growing epidemic is poor education regarding diagnosing childhood obesity, its associated complications, and effective methods of managing and preventing it. 

Defining childhood obesity

Over the past decade there have been heated debates over how to define childhood obesity. In adults, body mass index ≥30kg/m2 has been accepted as the cut-off for diagnosing obesity. However in children, BMI is not sufficiently accurate to diagnose obesity due to the differences in body composition changes occurring between genders and at different ages. Therefore, in order to account for these changes, children’s BMIs are now mapped on a graph specific to age and gender with cut-offs for overweight and obese based on percentiles of the population. While there are many limitations to and adaptations of this method, it has been shown to be as effective as, and superior to, other available methods of assessing the nutritional status of children and adolescents. 

Currently, obesity is clinically defined as being ≥98th percentile of children/adolescents of similar gender and age. Overweight has been defined as being ≥91st and <98th percentile. It should be noted that the cut-off ranges for population monitoring are different to those used for clinical assessment, with overweight and obese cut-offs of ≥85th percentile and ≥95th percentile respectively being used.⁴ For primary care physicians who don’t have access to centile charts, an online graph can be generated by inputting the child’s measurements on
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Aetiology

As stated, childhood obesity is a disorder with multiple factors having a causative role. There is no doubt that environmental factors have a huge role with high calorie food, sweetened beverages and time playing sporting activities being replaced by computer games and watching television being heavily implicated. However, there is a strong genetic component, with studies suggesting that 60-80% of the observed variance in body weight can be accounted for by inherited factors.⁵ Rare but recognised genetic causes of childhood obesity include Prader-Willi, Bardet-Biedl and Alström syndromes.

Approximately 2-3% of cases of childhood obesity are caused by endocrine disorders which include hypothyroidism, growth hormone deficiency and Cushing’s disease. With these conditions, progression along the height centile is often stunted.⁶

Risks associated with childhood obesity

Several conditions have been linked with childhood obesity. Obesity is often found in the presence of other abnormal metabolic changes which have been described as the ‘metabolic syndrome’. Metabolic syndrome is a constellation of metabolic risk factors including hyperlipidaemia, hypertension and hyperglycaemia.⁷ The incidence of metabolic syndrome in children and adolescents directly increases with severity of obesity. Not only does the prevalence of the syndrome as a whole increase, but each element contributing to the syndrome also worsens with increasing obesity.⁸ Childhood obesity is the leading cause of paediatric hypertension.⁹ Obese children have been shown to have a three-fold increased risk of hypertension compared to non-obese children, and adolescents in the 75th percentile have an 8.5 times increased risk of developing hypertension compared to adults.¹⁰ Furthermore, cardiovascular disease risk in adulthood increases incrementally with increasing BMI in childhood and adolescence.¹¹

In addition to the metabolic risks associated with childhood obesity, respiratory complications are also common. Obesity is the leading cause of obstructive sleep apnoea syndrome (OSAS) in adults, adolescents and children. It is recommended that all children with obesity should be screened for the presence of habitual snoring and presence of OSAS. While weight loss in these patients has been shown to significantly reduce the requirement for continuous positive airway pressure (CPAP), most patients maintain residual OSAS and therefore early intervention before OSAS develops is crucial.¹² Recent studies have also shown that there is an increased frequency of asthma in both overweight and obese children compared to those within the normal BMI range.¹³

Obesity has been shown to increase the risk of several cancers. In males, these include oesophageal adenocarcinomas, thyroid, colon and renal cancer. In females, obesity increases the risk of endometrial cancer, oesophageal adenocarcinoma, gallbladder and renal cancer.^14-17 Obesity from childhood can only exacerbate this situation.  

Orthopaedic complications of obesity in childhood and adolescence are well documented, with bony deformities leading to complications in the future. Such complications include slipped upper femoral epiphysis (SUFE), tibia vara and genu valga knee deformities, flat foot, scoliosis and osteoarthritis.⁹

Obesity in adolescence has also been linked with several menstrual abnormalities in girls such as oligomenorrhoea, amenorrhoea, polycystic ovarian syndrome, and hyperandrogenism.²⁰ Rapid early weight gain is associated with advanced puberty in both sexes, and a clear association exists between increasing BMI and earlier pubertal development in girls. However, in boys, pubertal development is often delayed and gynaecomastia a particular issue for self esteem.^20,21

Thus, obesity in childhood and adolescence is associated with a multitude of health problems both in early and adult life. Multiple studies have also shown that the likelihood of childhood obesity developing into adulthood obesity increases with the age that the child is obese, regardless of for how long.²² This means that not only are those with obesity during childhood at increased risk of developing the above co-morbidities, but the majority will maintain their obesity into adulthood and develop increased risk of conditions associated with adulthood obesity such as type 2 diabetes and stroke. The key to preventing such complications occurring is early detection, prevention and intervention. Understanding what conditions childhood obesity predisposes one to can help to illustrate to patients and families the importance of managing childhood obesity.

Management and prevention of childhood obesity

A recent study has shown that children in the 85th percentile are more likely to gain more weight and reach overweight status by adolescence, and thus intervention is warranted in children ≥85th percentile.²³ Early intervention is recommended even though several of the metabolic complications may not present until adolescence. It has been suggested that intervention before obesity and set behavioural patterns are established may be more beneficial and successful. The two main fronts from which childhood obesity should be tackled are the restriction of dietary intake and increasing physical activity. While this may seem simplistic, lifestyle intervention in children and adolescents has been shown to have poor compliance rates.²⁴ Education for parenting is paramount to a successful intervention to such an extent that counselling parents alone has been shown to have positive effects on weight loss.⁹

Mild caloric restriction is safe and effective in childhood obesity; however without appropriate increased physical activity, the weight loss from caloric restriction is usually transient. Extreme diets usually result in more dramatic weight loss; however these diets are unsafe, unsustainable and can often result in deficiencies in essential nutrients and vitamins.⁹ There is evidence to suggest that sugary beverages, skipping breakfast, eating outside of home (such as in fast-food restaurants) and increased portion sizes are linked with increased adiposity in children.²⁵ Simple ways of adjusting the diet to help maintain a better dietary quality include increasing the frequency of family meals, cutting out sweetened beverages, and eating breakfast. Increasing parental presence at evening meals is positively associated with higher quality of dietary intake and inversely associated with overweight prevalence among adolescents.^26,27

Strong evidence has shown that daily moderate-vigorous activity of ≥60 minutes duration helps reduce adiposity in overweight and obese youths.²⁸ In addition, other benefits of physical activity in youths have been shown, including reducing blood pressure, improving lipid profile, increasing bone density and mass, reducing depression and improving self-esteem.²⁴ The capacity to perform voluntary exercise decreases with rising BMI levels and, therefore, it is vital to begin regular exercise before complications and functional immobility from obesity arise.⁹ Suggestions to increase physical activity to ≥60 minutes daily (ideally in activities that involve the large muscle groups) and restrictions on sedentary behaviours such as television viewing, computer games and internet browsing can help overweight and obese children and adolescents to lose weight. 

Dietary adjustments alone or increased physical activity alone have relatively poor evidence to suggest maintained weight loss; however they are very effective in combination. When dealing with the issue of weight management, it is important to assess the motivation and willingness of both the patient and family, which if low, try and assess why. Ask the patient where they feel a good place to start would be and what adjustments they might be able to make initially. Setting realistic, quantifiable, sustainable, timed and personalised goals are crucial in achieving maintained weight loss. Scheduling a follow-up visit can help with motivation and monitoring progression.²⁵

If endocrine disorder is suspected as a cause for obesity, referral to a secondary care paediatric endocrinology unit is advised. 

Childhood obesity can be well managed in the community; however there are paediatric weight management clinics in some secondary institutions in Ireland. 

The development of appropriate public health initiatives to encourage healthy living in children in Ireland is a key component of what is needed. Parents and heathcare professionals alike find it difficult to identify children in the overweight category who are at risk to becoming obese.^29,30 Regular height, weight and BMI measurements in the community/schools (as are performed in other European countries such as Finland), would be an invaluable identification tool in establishing those at risk. 

References

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