Childhood and teenage overweight and obesity are growing challenges in developing countries, with up to 13% of South African children believed to be overweight or obese.

Overweight or obese children are more likely to experience negative consequences including low self-esteem and diabetes in adulthood.

The problem of obesity and related metabolic disease risk is not only experienced among adults (Kimani-Murage et al 2010). In fact, childhood obesity is becoming one of the most serious public health challenges of the 21st century, in both developed and developing countries (WHO 2016). In the USA, the average weight of a child has risen by more than 5 kg within three decades, to a point where a third of the country’s children are overweight or obese (Lobstein et al 2015). In just 40 years the number of school-age children and adolescents with obesity has risen more than 10-fold, from 11 million to 124 million globally (WOF 2016).

Further, a 2016 WHO estimate placed the number of overweight children under the age of five at over 41 million, with one quarter of those living in Africa (WHO 2016). This represents a doubling in prevalence among children over the past three decades (Davison and Birch 2008). It is also completely in line with the finding that, while the highest prevalence rates of childhood obesity have been observed in developed countries, its prevalence is increasing in developing countries as well (Sahoo et al 2015). In socioeconomically disadvantaged areas, weight control may not be an important priority when balanced against other problems the populations face (Anderson et al 2001).

In general, the prevalence of overweight has increased in the past four decades, but with later onset, and in some cases much more rapid increase in prevalence, in several low-income and middle-income countries (Matson and Fallon 2012). In South Africa, 13% of children are considered overweight or obese, more than double the global average of 5% (GBD 2015).

Childhood overweight has been associated with negative health consequences including non-insulin dependent diabetes, hypertension, and sleep apnoea, and negative psychological outcomes including depression, disturbed body image and low self-concept (Davison and Birch 2008). Of further concern is the fact that obese children and adolescents are likely to be obese adults at increased risk of cardiovascular diseases (CVD) and other morbidity, premature death, and impaired social, educational and economic productivity (Kimani-Murage et al 2010). Among 5- to 17-year-old children in a population-based sample, 70% of subjects had at least 1 CVD risk factor, while 39% of subjects had 2 or more CVD risk factors (Matson and Fallon 2012).

Due the negative consequences associated with childhood overweight, research assessing its causes is of utmost importance in order to guide the development of treatment and prevention programmes (Davison and Birch 2008).

Compared with children with a healthy weight, those with overweight or obesity are more likely to experience negative consequences (WOF 2016), including:

  • poorer health in childhood, including hypertension and metabolic disorders
  • lower self-esteem
  • higher likelihood of being bullied poorer school attendance levels and poorer school achievements
  • poorer health in adulthood, including a higher risk of obesity and cardiovascular disease
  • poorer employment prospects as an adult, and a lower paid job

Figure 1: Number of children aged 5-19 living with overweight or obesity in 2016, and the increase in prevalence from 2010 to 2016, by WHO region (WHO 2018).

Aetiology

The cause of adolescent obesity is regarded as multifaceted, given the numerous components that increase a child’s risk of developing the condition (Taylor and Taylor 2015). First, there is a known genetic link, as described in a study of twins with heritability estimates between 0.5 and 0.9 (Maes et al 1997). However, it is extremely likely that environmental factors in the child or adolescent’s home have a far greater impact since, as one report indicated, children aged <3 years being raised by obese parent(s) were more likely to become obese, suggesting an environmental, not genetic, aetiology (Taylor and Taylor 2015).

Much of the available evidence points to the cardinal importance of environmental factors in shaping habits that lead to (or away from) overweight and obesity, such as the finding that the availability of, and repeated exposure to, healthy foods is key to developing preferences and can overcome dislike of foods (Sahoo et al 2015). Mealtime structure is important with evidence suggesting that families who eat together consume more healthy foods (Sahoo et al 2015). Furthermore, eating out or watching TV while eating is associated with a higher intake of fat (Birch and Fisher 1998). Interestingly authoritarian restriction of junk food is associated with increased desire for unhealthy food and higher weight (Birch and Fisher 1998).

Additionally, variables outside the home – increased availability of high-energy foods and sugar-filled beverages at school, minimal advertising of healthful foods, lack of required physical activity at school, larger portion sizes, and more time looking at screens – have contributed to the current rates of adolescent obesity (Taylor and Taylor 2015). These factors can present challenges for any child regardless of social status, but children of low-income families often face further barriers to achieving a healthy lifestyle, including the lack of safe areas for physical activity and the expense of healthy food choices (Larson et al 2009).

Figure 2: Ecological model of predictors of childhood overweight (Davison and Birch 2008). Ecological model of predictors of childhood overweight (Davison and Birch 2008).

Lifestyle modification

The prevalence of overweight and obesity is increasing in children and adolescents worldwide, raising the question on the approach to this condition because of the potential morbidity, mortality, and economic tolls (Iughetti et al 2011). Childhood obesity can be slowed, if society focuses on the causes (Sahoo et al 2015). The most practical approach is the preventative one, and the importance of preventing adolescent obesity through lifestyle modification is well documented (Taylor and Taylor 2015).

Support for lifestyle modification (dietary and behavioural modification and physical activity) for both children and their families is essential for healthy living and a prerequisite for all overweight and obesity treatments (Matson and Fallon 2012). Behaviours that increase the risk of obesity are often easily identified, but persuading the whole family to change these behaviours remains a challenge, given that the promotion of excess energy consumption is ubiquitous in today’s society (Taylor and Taylor 2015).

Currently, older children are noted to spend less time engaged in physical activity, specifically during school hours and daily participation in physical education in schools has dropped from 42% in 1991 to 33% in 2009 among adolescents (Matson and Fallon 2012). To augment physical activity, decreasing the time spent in sedentary activities such as watching television and DVDs, playing video games, or using computers for recreation should be encouraged (August et al 2008).

Additionally, among patients already on an exercise regime, the odds for weight regain are twofold greater among those patients who are sedentary (August et al 2008). The importance of exercise in maintaining much of a person’s weight loss was one of the conclusions of a meta-analysis of long-term (3- to 5-yr) weight maintenance studies (27.2% weight loss retention in the low exercise group and 53.8% weight loss retention in the high exercise group) (Anderson et al 2001).

The evidence is mounting that, even if an exercise programme is followed, only a significant sub-group of patients maintain the weight loss in the long term (August et al 2008). One study found that only 25% of adults who had lost more than 10% of their body weight maintained their weight losses for more than 5 years (Anderson et al 2001). Lifestyle modification interventions such as exercise need to be intensive (calorie restriction, individual and family counselling, and daily exercise) and continued to be effective, which is challenging to maintain in children and adolescents (Matson and Fallon 2012).

Other factors, besides high levels of physical activity, associated with successful weight maintenance included continued reduced caloric intake, reduced fat intake, and reduced fast food consumption, particularly a reduction in sugary drinks (Taylor and Taylor 2015). Child characteristics such as gender and age influence the likelihood of participating in physical activity and sport and may differentially influence the benefits of physical activity on the maintenance of a healthy weight status (Davison and Birch 2008).

Alternative treatment options

While, the successful management of obesity is theoretically possible through lifestyle changes including diet modifications and increased physical activity, a literature analysis demonstrates that significant results are obtained only in a limited number of subjects and for a relatively short time period and that management with psychological involvement leaves the problem substantially unsolved (Davison and Birch 2008). Many studies have examined the link between sugary drink consumption and weight and it has been continually found to be a contributing factor to being overweight (Sahoo et al 2015). Sugary drinks are less filling than food and can be consumed quicker, which results in a higher caloric intake (Sahoo et al 2015).

Several policy tools are available to intervene in markets for better nutrition, including the setting of specific nutrient standards for products, the use of financial incentives and penalties to encourage reformulation, regulatory oversight of marketing activities, and the use of public-sector purchasing power to affect market prices and distribution (Lobstein et al 2015). However, interventions that affect food markets need political determination to challenge industrial interests, and this will need to be accompanied by approaches to reframe the narrative of responsibility for obesity and the determinants of the food environment, and these tasks are not easy (Lobstein et al 2015).

While primary prevention incorporates a lifestyle or system-level approach for all adolescents, regardless of weight, and a secondary prevention strategy centres on the overweight or obese adolescent as an individual, and incorporates a structured interventional method of change, a tertiary strategy is sometimes required, which encompasses management of overweight or obesity with pharmacologic therapies or bariatric surgical procedures (Taylor and Taylor 2015). However, surgery is generally not recommended for the treatment of obese children or a young person unless there are exceptional circumstances, such as if a child is severely obese and as a result, has comorbidities related to obesity (Londono-Lemos 2018).

Pharmacological interventions

It is suggested that pharmacotherapy (in combination with lifestyle modification) be considered if a formal program of intensive lifestyle modification has failed to limit weight gain or to mollify comorbidities in obese children (August et al 2008). Overweight children should not be treated with pharmacotherapeutic agents unless significant, severe comorbidities persist despite intensive lifestyle modification and a strong family history of T2DM or cardiovascular risk factors strengthens the case for pharmacotherapy (August et al 2008).

The pharmacological options for the treatment of paediatric obesity are limited (Ryder et al 2017). Medications approved for long-term obesity treatment, when used as an adjunct to lifestyle therapy, lead to greater mean weight loss and an increased likelihood of achieving clinically meaningful one-year weight loss compared to placebo (Londono-Lemos 2018).

The most commonly prescribed medication for the treatment of obesity in adults, phentermine, has a long track record without major safety concerns (Ryder et al 2017). This, coupled with its similarity to other stimulants which are widely prescribed for attention-deficit/hyperactivity disorder in children, phentermine may prove to be a viable pharmacological treatment option for paediatric obesity (Ryder et al 2017). The use of medications such as phentermine for the treatment of obesity is generally not recommended for children under 12 years (Londono-Lemos 2018). It has been demonstrated that, in subjects treated with phentermine, the weight loss was greater (from 2 to 10 kg) than in those receiving placebo (Iughetti et al 2011).

Treatment with phentermine, in addition to lifestyle interventions, has been shown to result in a statistically significant but modest increase in weight loss (Iughetti et al 2011). The authors of a long-term study into the efficacy of phentermine found that phentermine was somewhat more efficient at weight loss than both diet or amphetamine resinate, with very few side effects (Iughetti et al 2011). In a recent study to evaluate the weight loss effectiveness of phentermine as an adjunctive treatment to SOC lifestyle modification therapy among adolescents with obesity in the setting of a paediatric weight management clinic, phentermine added to SOC resulted in statistically significant weight loss at 1-month, 3-months, and 6-months among adolescents with obesity (Ryder et al 2017).

At 3- and 6-months, a higher proportion of patients on phentermine achieved a clinically meaningful weight loss of ≥ 5% BMI reduction, proving its long-term efficacy (Ryder et al 2017). Despite concerns, the study found no adverse changes in either systolic or diastolic blood pressure, which supports the further investigation of phentermine as a monotherapy or in combination with other medications as a treatment option for paediatric obesity (Ryder et al 2017).