Women in Soweto in their prime reproductive years (18-25 years) report being exposed to an obesogenic environment that makes it difficult to lead a healthy lifestyle. This study aimed to determine individual and community level predictors of these behaviours, as well as whether these behaviours were related to obesity status. Women (n = 1698) were recruited from their households as part of a survey study. Physical activity and sitting time was assessed using the Global Physical Activity Questionnaire (GPAQ). Participants were asked how frequently they used street vendors in a normal month, and dietary practices in the home and food insecurity were assessed using a questionnaire. Height and weight were measured. Individual and community level predictors were included in a series of linear regressions with either activity behaviours, or dietary practices as the outcomes. BMI was then treated as the outcome in a multinomial logistics regression. The majority of participants were normal weight, yet 44% were overweight or obese. Most participants were meeting the physical activity guidelines, yet less than half participated in leisure time physical activity. Most participants were meeting the sitting time guidelines, yet TV time was high. Age was positively associated with being overweight (ß = 0.145, p < 0.01) or obese (ß = 0.179, p < 0.01). Street vendor use was negatively associated with being obese (ß = - 0.236, p < 0.05), as was the community area in which women lived (ß = - 0.1098, p < 0.05). Both physical activity and sedentary behaviours were positively associated with higher socioeconomic status. Socioeconomic status was also negatively related to food insecurity and dietary behaviours. The environment in which young women live plays a significant role in the development of certain health behaviours, as well as in obesity prevalence.