BMC Public Health 2009, 9:485 http://www.biomedcentral.com/1471-2458/9/485 in other developing countries. Higher stunting among Palestinian boys might indicate that they suffer from micronutrient deficiencies as they are prone to make less healthy food choices [25], or it could be due to age-spe- cific differences in catchup growth between the sexes [33]. Stunting might also be associated with parasitic infections as suggested by some studies in developing countries [34]. A recent study from Gaza strip showed that the prevalence of intestinal parasites was 34.2% in children aged 6-11 years [35]. Since we neither could find recent data nor col- lected such data in the West Bank, we may only speculate if the higher prevalence of stunting in boys could be due to higher risk of infections as boys spend more time out- doors than girls. The prevalence of stunting among girls was low in general, but it was relatively high among girls living in rural areas and among those with low STL. Short stature may have an impact on girls and their reproductive outcomes; this may be even more important in the Pales- tinian context given the young median age of first mar- riage of 18 years and the high total fertility rate of 4.6 [10]. Onset of puberty was positively associated with over- weight/obesity and negatively associated with stunting and underweight. This might be explained by a larger pro- portion of the well nourished amongst those who have reached puberty in the sample. Similar association of overweight/obesity with onset of puberty has been found in other studies [16,22]. Although asking about Tanner stage would have given a more precise measure of sexual maturation, cultural taboos did not permit this. Limitations The study had certain limitations such as not including adolescents out of schools. The sample was not a national sample which makes it difficult to generalize the results to the whole of the oPt and limits the opportunity to com- pare our findings with similar data from other countries in the region. The sample was based on 8th and 9th grade stu- dents and the results reflect the prevalence of anthropo- metric measures in these two grades only. The corresponding age groups were mainly 13 and 14 years old, while the age group of 15 years was relatively small. Weights and heights were taken only once by one field worker, so that some measurements errors might not be accounted for. The student's questionnaire was not validated, but some questions were taken from the validated HBSC question- naire [17] and field workers were present when adminis- tering the questionnaire to explain questions when needed. A pilot study was done and unclear questions were modified. Moreover, the questionnaire was tested for reliability (a 1-week test-retest). The measures for the onset of puberty and household amenities had very high agreement between test and retest. The 1 week test-retest for the onset of puberty showed consistent answers in 92.3% in boys and 95.2% in girls, and that of the owner- ship of household amenities showed consistent answers ranging between 86.1% and 99.1%. Other strengths of the study include the fact that actual measurements of the weights and the heights were taken, its relatively large sample size, single stage cluster sampling method, the urban/rural distribution, and the high response rate. We also studied the association with certain sociodemo- graphic characteristics to identify the vulnerable groups for malnutrition. Conclusion Our findings suggest that both overnutrition and under- nutrition coexist in the study areas. This stage of nutrition transition is similar to low income economies where both under- and overnutrition coexist [36] and where overnu- trition is more prevalent among the more affluent strata of the society [7]. Both conditions may predispose to chronic diseases later in life. Urbanization, poverty, limited mobility and cultural restrictions on girls may all play a role. Future studies should address causes of overnutrition and undernutrition among Palestinian adolescents with rele- vance to preventive measures that could be instituted by the Palestinian health system given its limited resources. There is urgent need to improve nutrition to combat stunting, and to raise awareness about overweight and its associated health risks. Competing interests The authors declare that they have no competing interests. Authors' contributions NM contributed to the conception, design, data collec- tion, analysis and interpretation of data, and drafted the manuscript; HFA and GHO contributed to the concep- tion, design, analysis and interpretation of data, and revis- ing the manuscript. FA contributed to sample design, analysis and interpretation of data. All authors gave approval of the final version. Acknowledgements This study is a collaboration between Birzeit University and University of Oslo supported by a grant from the Norwegian Program for Development, Research and Education (NUFU) PRO X1 50/2002. We thank participating schools and Palestinian Ministry of Education and Higher Education and UNRWA Office of Education for facilitating field work. We are grateful to Alpha International for Research, Polling and Informatics for conducting field work and for statistical support. References 1. 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