台灣地區由於社會經濟蓬勃發展，國民平均所得逐年增加，生活、飲食習慣有所改變，高熱量、高脂肪及低纖維食品成為國人食物主要來源之ㄧ，進而導致熱量和脂肪的過度攝取，及營養供給的不均衡。台灣1998年公告的第三次全國營養調查結果顯示，國人身體質量指數有上升趨勢。 身體質量指數偏低或過高都有較高的死亡率。很多的研究顯示，許多慢性疾病的罹患率和死亡率會隨者身體質量指數的上昇而增加，故肥胖本身是一個獨立的危險因素。根據衛生署最新的資料統計顯示，2005年台灣地區主要死亡原因腦血管疾病、心臟疾病、糖尿病、高血壓分別為十大死因的第二、三、四及十位。肥胖與醫療資源利用及醫療費用亦逐年上升。 本研究欲以身體質量指數為衡量指標，進行體重過重、肥胖者與台灣健保醫療資源利用是否相關性之實證研究探討，並了解其對健保財務負擔影響程度，是否值得重視。研究資料取自國民健康局於2001年執行之「國民健康訪問調查」抽樣樣本，連結健保利用資料，並採最小平方法（ordinary least squares，OLS）為實證分析之方法。本研究以全樣本及男性樣本之模型實證結果發現，身體質量指數過低或過高，都會增加健保門診費用效果；個人的身體質量指數對門診健保費用的影響，並非線性，而是呈現U型的曲線。值得注意的是，以女性樣本之模型，身體質量指數並未顯著地影響健保門診就醫情形，這可能是台灣女性平時較注重健康，會留意體重的變化，以防止體重體重過輕或過重而引起病痛。 關鍵詞：身體質量指數、健保支出、醫療資源利用 / The Body Mass Index (BMI) Impact to the Expenditure of National Health Insurance on Taiwan Abstract Due to economic grows vigorously on Taiwan, the average income per person increase extremely year by year. Consequently, the living style and eating habit have significantly changes in searching major foods always with high colorific, full fat and low fiber. Therefore, it causes the body absorbing excessively of the colorific and fat as well as in unbalance supply of nutrition. The result of the third Nutrition and Health Survey in Taiwan (NAHSIT) announced in Year 1998, the Taiwanese’ Body Mass Index was toward to rise. Either lower or higher of Body Mass Index is always subjected higher death rate. Many researches show, there are high correlation coefficient between high percentage of chronic morbidity and death and up trends of Body Mass Index. Therefore, the obesity itself will be an independent dangerous factor. According to newest statistics of National Health Administration, Year 2005 in Taiwan, the main death reason from brain blood vessel disease, heart disease, diabetes, high blood pressure are ranking at the second, third, fourth and tenth of top ten cause of death respectively. Also the obesity is significantly associated with excess medical care cost and resources of hospitalization rising up year by year. This Research tends to apply Body Mass Index to be an indication of health measuring. Study and discuss the high correlation coefficient between overweighed and obesity and consuming resources of hospitalization of Taiwan. Meanwhile, it deserves paying more attention for understanding the influence level of financial to health insurance. The present data were derived from Bureau of Health Promotion which committee was implemented the National Health Interview Survey at Year 2001 and directly link to expenditure of National Health Insurance. The study method is adopting ordinary least squares (OLS) for real case analysis. This research discovered with the result of study model using completed samples and male samples, either lower or higher of the Body Mass Index will increase outpatient medical care cost. And there was a U-shaped association between Body Mass Index and outpatient medical care cost but liner-shaped. It deserves paying attention to the model of the samples of female, the Body Mass Index do not obviously encouraging them to see a doctor. Because of Taiwanese women relatively focus on the health regular, will look out for the change of the weight, in order to prevent the weight from being underweight or overweight and causing the illness. Keyword: Body Mass Index, expenditure of health insurance, resources of hospitalization