Ebook The prevention of overweight and obesity in children and adolescents: a review of interventions and programmes
During the past two decades the prevalence of overweight and obesity in children has increased rapidly worldwide (1–5). These trends have been associated with various changes in the social, economic and physical environment related to the nutrition transition (6). The nutrition transition is generally associated with an increase in the consumption of energy dense foods that are low in fibre, sugar, and sweetened drinks, a decrease in physical activity and a more sedentary lifestyle. Thus, overweight and obesity have become serious, large scale, global, public health concerns (7, 8). The obesity epidemic has been associated with a dramatic increase in related healthcare costs, for example in the USA a more than a threefold increase between 1979 and 1981 and 1997–1999 was observed (9).
Childhood obesity, itself, is associated with a wide range of serious medical complications. Early medical consequences of obesity include orthopaedic complications, metabolic disturbances, type 2 diabetes, disrupted sleep patterns, poor immune function, skin problems, impaired mobility, and increased blood pressure and hypertension (10). Childhood obesity has an immediate impact on a child’s physical appearance and can result in additional psycho-social consequences, such as a low self-esteem, social alienation, and lack of self-confidence (10, 11), discrimination (12) and, for girls, depression (13). Additional long-term health risks are partly related to the tracking of childhood obesity into adulthood. Long-term follow-up studies show that obese children tend to become obese adults (14–16). Related to the continuity of obesity into adulthood are long-term consequences of childhood obesity such as increased risk of cardiovascular disease, insulin resistance, type 2 diabetes, hyperlipidaemia, gall bladder disease, osteoarthritis and certain cancers (11). Moreover, adults who were obese children have an increased risk on morbidity and mortality independent of their adult weight (11). Obese children are more vulnerable to orthopaedic abnormalities related to damage to an unfused growth plate, slipped capital epiphyses, bowing of the legs and tibial tortion, sleep disorders, and insulin resistance has been noted even in children below 10 years (11).
The need for effective prevention of overweight and obesity is generally considered to be urgent. The disagreement is not whether to prevent overweight and obesity in children but rather when to introduce interventions on a wide scale and what preventive measures should be used. Calls for action have come from a number of sources including academics (17, 18) and politicians (19). As these calls for action gain attention, the debate between those who advocate immediate action vs. waiting for more evidence for effectiveness of preventive interventions has been increasingly polarized. On the one side, the need for immediate action is clear. We cannot continue to wait for more studies and more research while the epidemic continues to unfold unabated. Yet, the argument for additional research is also well founded. There is a dearth of data into specific causes of childhood obesity. Furthermore, there is a clear need for the continuation of research, using better and larger studies, with a long follow-up and improved research methodologies. Through this review we aim to identify the most promising elements of existing programmes and successful interventions that could be implemented and evaluated on a large scale.
Prevention and treatment of obesity and overweight may be somewhat easier in children than in adults because children are still growing in height. Related to the increased energy needs during growth, a child can achieve reductions in adiposity without reducing energy intake. One example of a treatment programme for obese children involves holding energy intake constant during growth in order to reduce a child’s body mass index (BMI) percentile and adiposity measures. Using such a treatment approach at a young age, reversing overweight and obesity can be achieved without drastic behaviour changes. Although paediatric studies show that the effects of all types of treatment approaches diminish over time, there is still evidence showing long term benefits related to obesity treatment (20). However, prevention has been shown to be potentially more efficient than treatment alone in addressing the obesity epidemic (21). Furthermore, effective prevention of childhood overweight is the first step towards preventing obesity. Effectively preventing obesity in childhood onwards may also prevent the onset of adult obesity and reduce chronic disease.
Preventing overweight and obesity requires understanding and addressing the ‘obesogenic environment’ in which children live. Environmental factors take precedence in prevention efforts because they provide the most potential for the greatest impact. Furthermore, other factors have played a lesser role in bringing about the current trends. Although gene–environment interactions may contribute to childhood obesity, genetics alone cannot explain the epidemic (22). It is the environment rather than genetics that has changed. Thus, we focus on population-based prevention childhood overweight and obesity prevention programmes, particularly interventions that address environmental determinants and can be applied on a large scale and are sustainable (preferably multi-sectorial).
The inclusion criteria for this review are broader than previous studies, with the goal of including more studies in order to provide insights into the state of-the-art in child hood obesity prevention programmes. Earlier reviews often had a specific, narrower focus. For instance, reviews focused only on interventions targeting obese children, only including interventions focusing on overweight or obesity, or restricting inclusion criteria to interventions with a randomized trial design. For example, Story (23) only included school-based obesity prevention programmes. Resnicow (24) restricted their review of school-based programmes to the ‘Know Your Body’ Programmes, with the aim of reducing cardiovascular risk. Reviews by Glenny (25) and Campbell et al. (26–28) are restricted to interventions with preventing obesity as a primary aim. Hardeman et al. (29) included only interventions with the aim of preventing weight gain. We further contribute to the literature by including a wider range of studies and by incorporating a qualitative perspective into our methodology.
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