These results demonstrate that the prevalence of overweight and obesity among youth has increased dramatically in the semirural town of Bogalusa, LA over the last 35 years, and rates do not appear to be slowing. Since 1973–1974 the proportion of children and adolescents who are overweight (including obese) has more than tripled, from 14.2% to 48.4% in 2008–2009. Similarly, the proportion of obese children and adolescents has increased more than fivefold from 5.6% in 1973–1974 to 30.8% in 2008–2009. These increases are seen in all age groups, in both girls and boys, and in both white and black youth.
Secular increases in the prevalence of overweight and obesity in US children and adolescents are well documented1, 8–11
and are generally consistent with our results. However, the prevalence of overweight and obesity seen in Bogalusa provides evidence that certain communities around the country may already be reaching levels of obesity that were not predicted to occur for another 10 years.12
The results of this study do not support recent observations based on NHANES data that childhood overweight and obesity prevalences may be plateauing.1
Compared to national levels of overweight and obesity, children in Bogalusa have experienced higher rates of increase since the early 1980's, and the gap appears to be widening (). The different interpretations of the current state of the childhood obesity epidemic given by the Bogalusa trends compared to NHANES-based national trends may be due, in part, to the variability of the NHANES estimates resulting from its relatively small sample size and complex sampling scheme; for example, in 2005–2006, while 16.3% of children aged 5 to 17 years were estimated to be obese, the 95% confidence interval ranged from 13.0% to 19.6%. Alternatively, these results may suggest that, although certain communities may be making strides toward arresting childhood obesity rates, others remain at high risk.
Figure 2 Bogalusa, LA compared to United States (NHANES): changes in the proportion of children and adolescents 5 to 17 years of age classified as being overweight (BMI ≥ 85th percentile; includes obese) (A) or obese (BMI ≥ 95th percentile) (B). (more ...)
The high levels of obesity seen in Bogalusa have also been seen in other rural communities in Louisiana. The LA Health Study, conducted among 2,709 children aged 8 to 15 years (average age 10.5 years) from 43 schools in rural communities across Louisiana, revealed that, in 2006, 45.1% of its study participants were overweight/obese and 27.4% were obese. Rural areas generally experience higher poverty rates compared to urban areas13
and are typically limited in their access to healthy food choices and opportunities for physical activity.14,15
Consequently, children from rural areas may be at a particularly risk high risk of obesity. An analysis of data from the National Survey of Children's Health revealed that nonmetropolitan residence and poverty were both independently associated with increased risk of obesity in children aged 10 to 17 years.16
Other research has noted increased risk of obesity among children from rural areas compared to children from urban areas, even after adjusting for markers of socioeconomic status.17
It is important to note that there do not seem to be any systematic differences in the observed secular trends in obesity among the race-gender groups, although black boys had the lowest prevalence of obesity at almost all time points. Recent data from the LA Health Study, conducted in rural Louisiana, also did not find any differences in the prevalence of obesity among black and white boys and girls.18
The similarities in risk of obesity across racial groups may be a phenomenon particular to rural areas, where environmental factors known to influence dietary and physical activity behaviors are potentially more homogeneous within a community. Although research focused on rural populations is limited, it appears that there may be smaller differences in levels of physical activity across racial groups in rural populations compared to urban ones.19
Taken together, results suggest that, in rural areas, interventions to address obesogenic social and physical environments may have broad reach across racial groups.
Our study was limited by the lack of data on socioeconomic status and how this may have changed over time. According to US Census data, the percentage of Bogalusa residents living in poverty was relatively stable from 1990 to 2000 (37% in 1990, 33% in 2000); therefore, at least at an ecologic level, the observed trends do not appear to be driven by socioeconomic changes in this population. Furthermore, race and poverty are highly related in Bogalusa (48% of blacks were living in poverty in 2000, compared with 21% of whites), yet we saw no differences in obesity trends and prevalence according to race, which suggests that in this population, socioeconomic factors likely would not explain the rising obesity trends.
The observations made from these secular trends have serious implications. Elevated BMI has been shown to have marked adverse associations with various risk factors including higher levels of blood pressure, abnormal levels of lipoproteins, and higher insulin levels.20
Also, current childhood obesity rates far exceed the objective set by Healthy People 201021
to reduce to 5% the proportion of children and adolescents who are obese, and more than a stabilization of the rates will be needed to meet this or any subsequent goals.