Objective: To identify the young adults' perception of their weight and examine the associations between young adults' weight perception and physical activities. Participants: A total of 4,882 participants' responses were derived from the Add Health, Wave III. Method: Chi-square tests were used to examine the weight perception and multinomial logistic regression used to assess the association between weight perception and physical activities. Results: Perceived weight and weight management among male participants were significantly different from female participants (p<0.001, p<0.001, respectively). Young adults with self-perception of being "slightly overweight" and "very overweight" were more likely of participating in physical activities such as gymnastic/weight lift/strength (OR = 0.91, p <0.001 and OR = 0.77, p<0.001) and walking (OR = 1.08, p<0.001 and OR = 1.13, p<0.001). Conclusion: The study showed that physical activities significantly increased the probability of accurate perceived weight. Steps should be taken to implement interventions that increase accurate weight perception and promote physical activity among young adults.