背景　依據統計資料顯示台南市國中生肥胖盛行率居全國國中生之第三位，學校護理師是推動校園健康促進重要的成員，了解影響青少年健康體位的原因是推動校園衛生政策的依據。目的　探討青少年的健康促進行為、血液生化指標及體位狀態之相關性。方法　採橫斷性、描述性之研究設計，採分層叢集隨機抽樣方法，以台南市41所公立國中參與學校健康檢查有抽血之學生為研究母群體。以青少年健康促進量表、體位狀態、血液生化報告為研究工具，研究時間自2010年6月至2011年5月，所得資料以描述性及推論性統計分析。結果　共有726位青少年參與本研究，其中22.2%體位過輕、23.8%過重和肥胖。健康促進行為得分越高，其多項生化指標及體位也越健康。由多元邏輯斯迴歸分析發現，男生、父親教育程度越低、每天上網電玩時間越多、運動行為得分越少，出現過重的機會越高，勝算比分別是1.93、1.75、1.07、1.04倍。結論／實務應用　本研究發現健康促進行為越佳，其生化指標越好、體位過重的機會也較小。此結果將可作為校園推行健康促進與健康體位等活動的實證依據。

Background: Tainan City has the third highest prevalence of junior high school student obesity of all administrative districts in Taiwan. School nurses play an important role in promoting student health. Understanding the factors that significantly impact student weight is critical to designing effective student health promotion programs.Purpose: This study explored the relationships between health promotion behavior and serum biomarker variables and body size.Methods: Researchers used a cross-sectional descriptive study design and stratified cluster random sampling. Subjects were 7th graders who received an in-school health checkup with blood test at 41 public junior high schools in Tainan City between July 2010 and May 2011. Research instruments included the adolescent health promotion (AHP) scale, serum biochemical profile and BMI (body mass index). Obtained data were analyzed using descriptive and inferential statistics.Results: Of the 726 students who participated in this study, 22.2% were underweight and 23.8% were overweight or obese. Higher AHP scores correlated with better biomarkers and body size. Multivariate analysis found factors that increased the risk of being overweight included: being male, having a father with a relatively low level of education, playing video games frequently, and doing little or no exercise (odds ratio = 1.93, 1.75, 1.07, 1.04, respectively).Conclusions / Implications for practice: Participants with relatively healthy behaviors had better biomarkers and a lower risk of being overweight. Findings can support the development of evidence-based school programs to promote student health.