Yost et al. BMC Public Health 2010, 10:465 http://www.biomedcentral.com/1471-2458/10/465 slightly or very overweight. Further studies are needed to determine the consistency of these findings among both U.S. and international female adolescents. In addi- tion, researchers and clinicians who design weight-loss interventions for female adolescents are encouraged to consider weight perception accuracy, not just BMI or weight perception. Additional studies with longitudinal designs are also needed to determine the validity of the association between age and efforts to lose weight among female adolescents. Results from the current study demon- strated older female adolescents are more likely than their younger counterparts to be trying to lose weight, a finding that is consistent with previous research [22,26]. However, studies have also demonstrated negative [42] and nonsignificant [25] associations between adoles- cents’ age and efforts to lose weight. Consistent findings from future research will allow clinicians to identify whether weight-loss interventions should be aimed at older, younger, or all female adolescents. Weight-loss interventions targeted towards or designed specifically for Black/African American U.S. female ado- lescents may also be needed. Black/African American female adolescents in the study had a relatively high pre- valence of overweight and obesity (38.19%) and a low prevalence of perceiving themselves as slightly or very overweight (36.94%). Also, compared to the other race categories in this study sample, Black/African American female adolescents who were overweight or obese were the most likely to inaccurately underestimate their weight (10.74%), and they were significantly less likely than their White counterparts to be trying to lose weight. This study identified significant associations between BMI, weight perception, and weight perception accuracy with trying to lose weight. In addition, a relatively large number of this study’s sample reported engaging in exer- cise as a weight-loss method (n = 796). Thus it is surprising that these variables were not associated with engaging in exercise as a weight-loss method. It is possible that female adolescents may engage in other healthy, unhealthy, or extreme weight-loss behaviours in addition to or in place of exercise. Including additional weight-loss behaviours in this study’s regression models may have strengthened the model, possibly allowing for significant associations. Thus, additional healthy and unhealthy weight-loss behaviours are recommended in future research on the associations of BMI, weight perception, and weight perception accuracy with engaging in exercise as a weight-loss method among overweight and obese female adolescents. Limitations Use of the Add Health data [30] in this secondary-analy- sis study limited the statistical analyses of data and the generalizability of the study’s findings. The Add Health Page 9 of 11 sample was selected from a school-based sample; thus, findings are only generalizable to U.S. female adoles- cents enrolled in school. Furthermore, the underlying survey design of the Add Health study did not allow for inferences of cause and effect. Although a well-powered study sample with data from more than 2,000 subjects was available for analysis, there was a relatively small number of subjects who were overweight or obese, which did not allow for separate analyses for overweight and obese subjects. The weight perception accuracy variable, therefore, combined subjects who were over- weight with those who were obese, and statistical analy- sis was unable to consider differences in weight perception accuracy between overweight and obese sub- jects. Also, the conceptualization of weight perception accuracy and the subjects’ interpretation could have affected their responses, making it difficult to “match” the BMI categories of overweight and obese with the weight perception categories of slightly overweight and very overweight. In terms of validity and reliability, there was a lack of reported measures, and recom- mended techniques were not available for this second- ary-analysis study. Conclusions Based on the findings of this secondary analysis of data from the Add Health study [30], BMI, weight percep- tion, and weight perception accuracy are significantly positively associated with the likeliness of trying to lose weight among U.S. female adolescents. However, BMI, weight perception, and weight perception accuracy are not associated with the likeliness of engaging in exercise as a weight-loss method among U.S. female adolescents; nevertheless, this finding does not indicate that such associations do not exist. Considering the strengths and limitations of this study, results should be interpreted with a degree of caution. Although this study’s results support findings from previous research regarding ado- lescents’ efforts to lose weight, the current investigation is the first known study to consider the association of weight perception accuracy with trying to lose weight and engaging in exercise as a weight-loss method among overweight or obese U.S. female adolescents. To help reduce the national and worldwide epidemic of overweight and obesity among female adolescents, weight perception accuracy, as well as age and race, must be considered as significant factors associated with weight-loss efforts among female adolescents. Acknowledgements This research uses data from Add Health, a program project directed by Kathleen Mullan Harris and designed by J. Richard Udry, Peter S. Bearman, and Kathleen Mullan Harris at the University of North Carolina at Chapel Hill, and funded by grant P01-HD31921 from the Eunice Kennedy Shriver