Obesity is a disorder that result from excessive body fat accumulation. Etiology of obesity is not clear, but generally obesity caused by imbalance of intake and energy utilization which energy intake is more than energy utilization. Alteration of consumption pattern and low physical activity at daily life also determine body fat accumulation that cause obesity.This research aimed to analyze physical activity and fast food consumption as risk factors toward obesity at 1st Senior High School of Kendari. This is an observational stuy with case control design. This research's sample consist of 47th cases and 47th controls that selected by random sampling. Data was analyzed by using Odds Ratio. This research's instruments were scale, microtoice and questionnaire for physical actovity and fast food consumption among students at age 16-18 years old at 1st Senior High School of Kendari 2018.Result of this research shown that physical activity is a risk factor for obesity (OR = 8,181 ; 95% CI = 3,181-21,035) and fast food consumption is a risk factor for obesity (OR = 14,578 ; 95% CI = 5,083-41,809) among students of 1st Senior High School of Kendari. This research's conclusion are low physical activity and fast food consumption more than 3 times for a week were risk factors for obesity among students at 1st Senior High School of Kendari.