Abstract:Background: Young adult women (18-36 years) are gaining weight at rates higher than women in other age groups. Given its long term deleterious health effects, it is important to know the determinants of this weight gain. However, other than in relation to pregnancy, little is known about the determinants of weight gain in this population group.Method: Papers examining non-pregnancy weight gain in young women were identified through a literature search in PubMed in August 2008. Subsequently, reference lists of included papers were checked for additional eligible papers. Results: 29 papers were included in this review. They were grouped into five categories on the basis of the main identified determinant of weight gain: contraception (4); dietary behaviours (3); quitting smoking (1); physical activity (1) and university transition (20 papers). Study duration ranged from 13 days to 15 years. Weight was objectively measured in 25 studies and selfreported in 4 studies. 27 papers reported weight gain; the highest rates were observed with initial exposure to contraceptive use and the first semester of university.Conclusions: Even though young adulthood is a vulnerable time for weight gain in women, the number of studies examining specific determinants of weight gain was small.Those located identified five social and behavioural determinants, with most of the research focussing on the transition to and through university, and few studies in nonuniversity populations. More studies are needed to assess the concurrent contributions of multiple determinants of weight gain at this life-stage, so that appropriate interventions to prevent excess weight gain can be developed.