In the current issue of IJ Health there are two aeticles assewsing obesity in children and the economic of medical treatment of sequences of obesity [1, 2]. Obesity is considered one of the fastest growing epidemics of the developed world, which is also spreading to the developing countries. Currently, in the United States, about 127 million adults are overweight, 60 million are obese, and nine million are severely obese [3]. Obesity increases risk for a variety of diseases. Hence, prevention of obesity is an essential responsibility of public health, not only because of its association with diseases, but also because of the economic implications and predisposition to co-morbidities. Obesity is a very significant risk factor for Coronary Artery Disease (CAD), which can lead to myocardial infarction. Obesity is associated with hypertension, high triglycerides, and high LDL cholesterol levels, which indeed are major risk factors for the CAD and stroke. It also results in lowering of cardioprotective HDL levels. However, heart disease and stroke reflect only the tip of the iceberg. [1] Since obesity is now identified as a global health problem in both developed and developing countries. Japan is not an exception. [2] investigation observing the change in the proportion of obese individuals in Japanese adults from 1976 to 1995, found that the body mass index (BMI) in men increased by 0.44 over a period of 10 years. The Examination Committee of Criteria for Obesity Disease in Japan, the Japan Society for the Study of Obesity, specifies lipid metabolism disorders and diabetes mellitus as health problems caused by or related to obesity requiring weight loss. It is also known that the incidence of health problems increases as the degree of obesity increases. The National Health and Nutrition Examination Surveys (NHANES) I to III and showed that increased BMI was associated with an increased incidence of obesity-related disorders. The National Institutes of Health also indicates that the incidence of low HDL cholesterolemia and hypertension is markedly higher in individuals with a BMI of 30 or more [2] Association of the degree of obesity and health problems has direct implication for medical costs. The relationship between the degree of obesity and annual medical costs, number of inpatient days was recently reported, number of outpatient visits, and medication costs in members of a health maintenance organization in the United States. Compared with individuals with a BMI of 20 to 24.9, annual medical costs were 25% greater in individuals with a BMI of 30 to 34.9 and 44% greater in those with a BMI of 35 or more. Those medical costs increased in individuals with higher BMI in the United States and in Australia. Similar results in Japanese individuals were reported. Compared with individuals with a BMI of 21.0 to 22.9, total medical costs were 1.10 times greater in overweight individuals with a BMI of 25 to 29.9 and 1.22 times greater in obese individuals with a BMI of 30 or more, indicating increased total medical costs with increasing BMI. These studies did not focus on obesity-related disorders such as hyperlipidemia or estimate the impact of obesity on total medical costs [2]. In Japan, only one anti-obesity drug is now covered by national health insurance, and reimbursement is based on a very strict criterion of BMI of 35 or more. However, analysis of the relationship between BMI and medical costs of obesity-related disorders is very important in the context of multiple anti-obesity drugs under clinical development in Japan, possibility of review of the criteria for health insurance coverage of the anti-obesity drug, and an increase in the number of obese individuals. Editorial: Obesity Is A Spreading Modern Life Health Problem 2 of 3 The present Paper [2] focused on the medical costs of hyperlipidemiadepending on d ata from the National Health and Nutrition Survey were used to determine the percentage of individuals with hyperlipidemia among those with a risk factor of BMI equal to or greater than a certain level. This paper results imply that change in the BMI-based criteria for obesity is associated with a substantial increase or decrease in avoidable medical costs of hyperlipidemia.