The objective of this study was to analyse the methods being used to control food intake and physical activity in RCTs of human obesity. Methods: A total of 21 randomized controlled trials (RCTs) were investigated. Nine of which were domestic studies from http://oasis.kiom.re.kr and the other of which were foreign studies from systematic reviews of RCTs on herbal medicine for treatment of human obesity. Results: According to domestic studies, low calorie diet were recommended in five cases of the domestic studies , maintain current dietary habit were recommended in two and no information on diet was two. Considering the seven cases where the information on diet was available, patients`` food intake were checked at every visit in six cases. Only two cases among the six had been dropped owing to the violation of dietary habit by patients. Exercises were prohibited in two cases, maintain current level of phisical activity were recommended in three cases and, from the rest, no information was available. The level of physical activity were not strictly controlled by any means hence no drop out. According to foreign studies, low calorie diet were recommended in two cases, very low calorie diet (less than 700 kcal/day) in one case, maintain current dietary habit in two cases, do not eat fat in two cases and no information was available in the rest five cases. Exercises which concerns spending about 300 kcal/day was recommended in one case, moderate exercise were recommended in three cases, maintain current level of physical activity were recommended in three cases and no information available in the rest five cases. Conclusions: In order to improve the accuracy of RCT, for the dietary side, researchers should record patient food intake at every visit by means of 24-hour dietary recall methods. This can be supplemented by multiple choice survey that are designed to help patients to diagnose themselves more accurately leading to less bias. For the exercise side, it is highly recommended to confine the exercises to walking only so as to quantify the amount of physical activity more easily by using pedometer.