本研究以新竹市兩所國中二、三年級學生為對象，希望瞭解國中生自我效能與體重控制成效間的關係，以及體重控制行為扮演的中介角色。本研究以立意抽樣方式抽取樣本，共獲得193份有效樣本，分別以飲食行為量表、身體活動量表及健康自我效能量表進行測量。分析有效問卷內容發現：飲食控制行為方面，以「飲食內容」的平均得分最高（平均值3.57，標準差0.67），其次為「特定食物攝取」（平均值為3.46，標準差0.48）。進一步進行分析發現，飲食自我效能與運動自我效能相關係數為0.618（p＜0.01）具顯著相關。女生在飲食自我效能上得分高於男生。而父、母教育程度對於國中生飲食內容具顯著差異，大專以上教育程度者平均值高於高中職及國中（F=5.83, p＜0.01）及（F=3.67, p＜0.05）。最後，以階層迴歸分析個變項間關係，扣除控制變項的影響後，運動自我效能對飲食內容（β=0.141, p＜0.05）具有影響力，△R^2為7.7%；飲食自我效能對特定食物攝取（β=0.378, p＜0.01）具有影響力，△R^2為10.2%；飲食自我效能對飲食行為（β=0.465, p＜0.001）具有影響力，△R^2為17.7%；運動自我效能對身體活動（β=0.491, p＜0.001）具有影響力，△R^2為17.9%。除此之外，自我效能及體重控制行為對於身體質量指數（Body Mass Index, BMI）都沒有直接影響，建議未來研究應考慮增加其他成效指標。此研究結果可提供學校健康衛生教育者在飲食衛教及身體活動規劃時參考。

The purpose of this study was to explore the relationship between the effectiveness of junior high school students' self-efficacy and weight control. The subjects were the second and third year students in two schools in Hsinchu City, Taiwan to investigate the mediating role of weight control behaviors. By using the purposive sampling method, a total of 193 valid samples were recruited. Dietary behavior score, the Physical Activity Scale and Health Self-Efficacy Scale were administrated. The dietary content is the highest average score (mean=3.75, standard deviation=0.67), then followed by specific food intake (mean=3.46, standard deviation=0.48) in diet control behavior content. Further analysis found that dietary self-efficacy and exercise self-efficacy correlation coefficient was 0.618(p＜0.01), with statistical significant. The girls' score were higher than boys' on diet self-efficacy. Secondly, we found that the education level of parents may have effect on student dietary content, those students whose parents graduated in college will have higher scores than graduated in senior high school (F=5.83, p＜0.01) or junior high school (F=3.67, p＜0.05). Finally, after the hierarchical regression analysis of the relationship between two variables, with control of other variables, the results were: exercise self-efficacy may associated with the dietary content (β=0.141, p＜0.05), ΔR^2=7.7%; diet self-efficacy (β=0.378, p＜0.01) may associated with on specific food intake, ΔR^2=10.2%; diet self-efficacy may associated with eating behavior (β=0.465, p＜0.001), ΔR^2=17.7%; exercise self-efficacy may associated with on physical activity (β=0.491, p＜0.001), ΔR^2=17.9%. In addition, self-efficacy and weight control behaviors are not directly associated with body mass index (BMI). These variables may affect the BMI in ways not mentioned in this study; therefore additional research in this area should consider adding other performance indicators. It can provide future suggestions for the enactment of policy on students and parent nutrition education in order to improve both mentally and physically health development of adolescents.