CONSENSUS DOCUMENT AND CONCLUSIONS

 

Successful intervention models for obesity prevention: The role of healthy life styles

Modelos exitosos de intervención para la prevención de la obesidad: el papel de los estilos de vida saludables

 

 

Vicente Martínez Vizcaíno^1*, Jorge Cañete García-Prieto¹, Blanca Notario-Pacheco¹ and Mairena Sánchez-López^1,2

¹Social and Health Care Research Center. Universidad de Castilla-La Mancha. Cuenca. Spain
²School of Education. Universidad de Castilla-La Mancha. Ciudad Real. Spain

Correspondence

 

 

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ABSTRACT

Children obesity is considered a serious public health problem around the world. In Spain, the prevalence of overweight/obesity is reaching alarming figures, exceeding 35% of the children. Several hypotheses suggest that the energy balance model does not fit very well when analyzing the causes of the current obesity epidemic and, although genetics seems to explain up to 30% of the likelihood to become obese in infancy, has been suggested that genetics might be influenced by environment factors including vigorous physical activity (PA). Some recent systematic reviews indicate that there is enough evidence about the effectiveness of interventions to prevent obesity in children 6-12 years old; however, the heterogeneity of the effect, and the potential selection, information and publication biases that undermine the validity of these studies, thus their results should be interpreted with caution. In Spain, an extracurricular PA program of leisure-time (MOVI) has evidenced some effectiveness on reducing the adiposity and on improving the lipid profile in schoolchildren. To overcome some weakness of MOVI program, a second edition of this study was designed. The objectives of this review are twofold: 1) to analyze latest data of the obesity epidemic in Spain; and 2) to describe the main features of MOVI-2 program, and overall of the successful interventions to prevent children obesity.

Key words: Obesity. Interventions. Children. School. MOVI program.

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RESUMEN

La obesidad infantil continúa siendo un serio problema de salud pública en todo el mundo. Las cifras actuales en España son alarmantes, y se sitúan en torno al 35,4%. Hay varias hipótesis que apuntan a que el modelo de balance energético como causa de la obesidad infantil no se sostiene. Y aunque las razones genéticas parecen explicar hasta el 30% de la probabilidad de llegar a ser obeso, se ha sugerido que esta herencia podría ser influenciable por factores ambientales entre los que se encuentra la actividad física (AF) vigorosa. Aunque las últimas revisiones señalan que existe evidencia suficiente sobre la efectividad de las intervenciones para prevenir la obesidad en niños de 6-12 años, la heterogeneidad del efecto encontrado en los resultados y la posibilidad de sesgos de diseño y de publicación de los estudios hacen que los resultados deban interpretarse con cautela. En España la intervención MOVI, un programa extraescolar de AF de carácter recreativo, ha conseguido disminuir la adiposidad, y mejorar el perfil lipídico. Para superar potenciales limitaciones de la primera intervención, se diseñó una segunda edición. Los objetivos de esta revisión fueron: 1) analizar los últimos datos de la epidemia de la obesidad infantil en España; y 2) describir las principales características del programa MOVI-2, y en general de las intervenciones que han sido efectivas para prevenir la obesidad en niños.

Palabras clave: Obesidad. Intervenciones. Niños. Escuela. Programa MOVI.

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Introduction

Children obesity remains a serious public health problem around the world¹. In Spain, current prevalence rates range from 35% to 42%.^2,3 Although recent studies have shown a leveling-off or even a decline in the prevalence of overweight/obesity in children in different countries of the world,^4,5 in the period 2004-2010 prevalence of overweight in boys aged 8-11 years from Cuenca, Spain, increased from 21.6% to 28.0% and the percentage of body fat from 22.6% to 24.0%. In girls, however, the trend seems to have stabilized.²

In parallel to the growing trend in the overweight prevalence, during the last decade of the 20^th century underweight prevalence was increasing in Spain, from 2.7% in 1992 to 9.2% in 2004 in children 9-10 years,⁶ and in other European countries⁷. Fortunately, latest estimations reported in Spanish children show that from 2004 to 2010 the underweight prevalence has not increased, and stands at around 8.5%.²

Therefore, the population approach for addressing the prevention of overweight, as in other public health problems, we should to be into account the classic good practice Latin axiom primum non nocere, so that it might be that interventions whose effectiveness on reducing overweight is controversial have also an undesirable effect increasing the proportion of underweight children.

Determinants of the obesity epidemic in Spanish children

At the individual level, body fat accumulation results from an imbalance between energy intake and energy expenditure. If intake exceeds expenditure the excess of energy will be stored as fat. On the other hand, it has been estimated that genetics susceptibility explains about the 30% of the likelihood of child will develop obesity,⁸ although this is a polygenic inheritance strongly influenced by the interaction genes, environment and lifestyle.⁹

However, at the population level non-genetic factors are the responsible for the frequency of obesity, including epigenetic,¹⁰ eating behavior patterns at an early age, activity/inactivity patterns, and other psychological, social and environmental factors.⁹ Nowadays, the relative importance of energy expenditure and intake in the development of the current obesity epidemic is a debatable issue. A recent review of studies addressing this question in different regions of the world¹¹ concluded that in view of the great variability in the study designs, in the exposure and outcome measures used, and the wide population range in which the studies were based, the estimation of the importance of each one of these two factors, intake and energy expenditure, was not possible in children and teens.

In Spanish children, however, there are some considerations that worth to examine, and that leading us to suspect a greater importance of the decreasing of energy expenditure as determinant of the current obesity epidemic. First, data from both the AVENA study¹² and the enKid study¹³ support the association between overweight and TV hours in Spanish children and adolescents. Furthermore, baseline measurement of an intervention study not yet published by our group,¹⁴ show that children who are overweight or obese consume on average less calories/day than children with normal weight, and these normal weight children less than thinness children. After a first view of these data might be argued that children with overweight/ obesity do less daily physical activity than less normal weigh children, but when we controlled in multivariate models for cardiorespiratory fitness levels, a variable closely related to physical activity levels, these differences in energy intake by weight categories remain unchanged. These results are in accordance with that reported from other studies,^15,16 and support the new hypothesis proposed by Gutin suggesting that vigorous physical activity at early ages would have a pivotal role in the of stem cells differentiation in bone and muscle tissues through stimulation by mechanical influences such as physical activity¹⁷. If this theory were consolidated would have important implications in determine which is the best age range for implement preventive interventions, and which is the most appropriate type of activity for it.

There are several hypotheses that do not support the energy balance model for explaining the childhood obesity epidemic, and even though no one doubt of the importance of genetics on predicting obesity, it has been suggested that genetics could be very strongly influenced by environmental factors including vigorous physical activity.^18,19

Efectividad de las intervenciones preventivas sobre obesidad infantil

A Cochrane systematic review aimed to evaluate the effectiveness of interventions for preventing obesity in children and adolescent concluded that there is enough evidence on the effectiveness of interventions to prevent obesity in children aged 6-12 years, although should be considered that the heterogeneity of the effect found in the studies, as well as the risk of design and publication biases, and therefore this results should be interpreted with caution. Furthermore this review concludes by recommending for future studies: 1) analyze the long-term results, 2) assess how those interventions that are effective can be maintained over time in a sustainable manner, 3) include economic evaluations, 4) potential damage reporting (i.e. eight reduction in thinner children, reduction of essential nutrients, etc.), 5) subgroup analysis by gender, location, race or socioeconomic status, 6) describe in detail the activities carried out in the intervention (to facilitate their applicability and transferability to other populations), and finally, 7) to focus on children 0-5 years.²⁰

A recent meta-analysis whose objective was to assess the efficacy of intervention programs on the body mass index (bMi) of children and adolescents, as well as explore the possible differences between the school and after-school intervention programs showed school or after school interventions had a similar effect.²¹ Considering that in Spanish context seems very complicated to propose legislative changes aimed to include interventions to tackle children obesity in the schools curricula, the implementation of interventions at recess or after school seems to be more feasible.

The conclusions of a review that examines the systematic reviews and meta-analysis aimed to evaluate the effectiveness of programs addressing the prevention and control of childhood obesity indicates that information about the barriers and challenges encountered when designing and implementing interventions in real life situations will provide important information on feasibility and sustainability, and identify if failure or modest success of the intervention was due to a problem with the intervention's development, content or implementation.²²

Most of the systematic reviews emphasize on the importance of taking into account the theoretical models of behavior's changes in which the intervention is based.²³ The usefulness of these models in in the development of intervention strategies that affect multiple areas has been proven in several studies.^24,25 One of the most commonly used is the socio-ecological model.^26,27 This model distinguishes several levels on influence on behavior usually depicted as a graph with concentric circles (fig. 1). At the central level are represented the biological/genetic, physiological and sociocultural influences that make-up the individual's identity. In the second circle are placed personal relationships, the environment close to the children; this micro-system consisted of relationships with parents, teachers, sibling, and friends. A third level of influence it's known as exo-system, and includes physical and social environments that influence children's behavior, but without interacting (neighborhood and its built environment, media, location of the school, working conditions of parents, etc.). Finally, the macro-system (fourth level) influences the child's behavior; this macro-system includes traditions, social, culture, laws, history, etc., of the country where the child growths.

 

 

This paper review the characteristics of the most promising interventions.

 

Results

Table I shows characteristics of 12 effective school-based interventions on prevention obesity in children (6-12 years). All studies were randomized controlled trials, implemented in school area, and included as outcome BMI or prevalence of overweigh/obesity.

Six studies were conducted in the United States, one in South America, one in Australia and four in different countries of the European Union (Spain, Switzerland, Germany and Sweden). Most of the studies were done in school (with modifications into curriculum),^28-36 two studies were done in after school schedule (FitKid and MOVI),^37-40 and one was done jointly in school and after school (STOPP).⁴¹ The duration of follow-up ranged from 3 months to four years; of these 12 studies, 2 studies had a follow-up period of 3 months, 5 studies between 8 months and one and a half year, and 6 studies more than one and a half year (two, three o four years). Seven of the interventions included increase in physical activity levels or reduce sedentary time, and the rest combined increase in physical activity levels or reduce sedentary time and diet. It is noteworthy that none study exclusively focused on diet was identified. Five of them were designed from the perspective of theoretical models of behavior change (FitKid, Switch-play, PAAC, KISS and Planet Health).

Participants' characteristics

One study included girls only (Dance for Health) and the rest included both girls and boys, although only two of these reported sex specific results (MOVI and Planet Health). The mean age at baseline varied from 6 to 12 years (median 9.5 years). One study involved a participants group with overweight/obese (KOPS), and the rest involved children recruited from all body mass index categories.

Types of outcome measures

Five studies reported BMI or prevalence of over-weigh/obesity and seven studies reported furthermore BMI or prevalence of overweigh/obesity of at least one measure of adiposity. Three of them measured cardiovascular risk factors (FitKid, MOVI and KISS); four, objectively physical activity (KISS, Switch-play, PAAC and STOPP); four, fitness (FitKid, KISS, Healthy school, El Paso Catch); three, physical activity related behaviours (Dance for Health, Planet Health, KOPS) and three, diet-related behaviours (Planet Health, KOPS, STOPP). Only one study included results on quality of life (KISS).

Effectiveness of the interventions in Spanish settings

The MOVI interventions in schoolchildren

Two interventions focused on the promotion of physical activity in the school setting have been tested in the last years by our group. The distinguishing characteristics of MOVI interventions are the following: 1) in children in 4th and 5th of Primary School (age ranged 9-11 years); 2) recreational, non-competitive, leisure time physical activity; 3) open to all the children, and suitable for everyone, regardless of their body composition or motor skills; and 4) takes place outside school hours but in the school sports facilities (www.movidavida.org).

This intervention, in its first edition (three sessions per week, each one of 90 minutes of moderate and vigorous intensity physical activity, lasting two school years) showed moderate effect in reducing adiposity and improving the lipid profile, but did not significantly improve overall cardiometabolic risk because of did not reduce insulin levels.^39,40 Our working hypothesis was that another intervention increasing the intensity of the program, putting more emphasis on the development of muscle strength, and including a weekend session on Saturday morning because we suspected that in the first edition compensating behaviors during weekend might be responsible of mitigate the effects of the intervention; therefore we implemented a 2nd edition of MOVI including two after school 90 minute sessions on school days and a 150-minute session on Saturday morning, during a school year) hypothesizing that this new intervention could be more effective on reducing obesity, but also remain acceptable to parents and school authorities. In addition, the MOVI-2 intervention,¹⁴ included as objectives to produce behavioral changes in children and parents similarly to other effective previous interventions (CATCH, M-SPAM).

The main objective of MOVI-2 was to evaluate the effectiveness of an intervention that essentially consisted of implementing a standardized leisure time physical activity program aimed to reduce overweight/obesity and other cardiovascular risk factors, and lasting one academic year. As secondary objectives we plan to evaluate the impact of MOVI-2 on other health-related variables: physical fitness, duration and quality of sleep, health-related quality of life, and academic performance. Among the most notable results of this cluster randomized clinical trial, in preliminary analysis, worth noting a decrease in body fat, an increase in lean mass, and a decreased in insulin levels.

The experience of these two consecutive interventions makes us feel able to provide some recommendations for future interventions to tackle against childhood obesity in the Spanish context:

1) Because of the magnitude and consequences of childhood obesity not only at this moment but also in the future, it is a priority testing the effectiveness of interventions for controlling this epidemic in Spain; otherwise we would expect an increase in morbidity/ mortality and other cardiovascular diseases in the coming years.

2) The most appropriate interventions in Spanish children to prevent obesity should be based on the promotion of physical activity so that: a) it has been repeatedly reported low levels of physical fitness in Spanish schoolchildren, particularly from data of the AVENA study;¹² b) unpublished data from our group indicate that the caloric intake of overweight children is not greater than in normal weight or underweight children; c) a exclusively diet based intervention may not be free of risk for thinness children; and d) an intervention to promote physical activity based on playground games could improve other health-related aspects such as quality of life, academic performance, time and quality of sleep, etc.

3) Although it is generally accepted that BMI is the most useful and practicable indicator of excess of adiposity on clinical and population based studies, it should taken into account that BMI does not distinguish between fat and lean body mass. Therefore, it seems advisable include in population interventions focused on promoting physical activity in children as the main outcome, in addition to BMI, an indicator of body fat such as skin-fold thickness or body fat measured by bioimpedance,²² so that physical activity might reduce fat while increasing muscle mass, and as consequence the weight/height ratio would remain unchanged.^17,39

4) Early infancy is probably the best opportunity to intervene, so that is considered the best age to establish perdurable healthy behaviors. Furthermore, it is known that the risk of obesity in adulthood is much higher when early adiposity rebound occurs.⁴²

5) Consistent evidence indicate that genes explain up to 30% of the likelihood of becoming obese; however epigenetic hypothesis support that genetic expression could be influenced by environmental factors, and vigorous physical activity is one of the most influential factor.^18,19

6) The school environment is considered the most suitable setting for carrying out physical activity interventions on children because of: it is possible targeting to large segments of the youth population, students spend a considerable amount of day in school, most of schools provide health education (physical activity and nutritional habits) and, finally, the school environment provides a powerful social network of teacher and peers.²²

7) The design of the interventions should be based on theoretical models of behavior change. A main limitation for most of obesity interventions in children is that the lack of theoretical underpinning on behavioral change models threats the perdurability over time of the effect.

 

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Correspondence:
Vicente Martínez Vizcaíno
Centro de Estudios Sociosanitarios
Universidad de Castilla-La Mancha
Santa Teresa Jornet, s/n
16071 Cuenca
E-mail: Vicente.Martinez@uclm.es