This systematic review assesses weight loss interventions in young adults (18-25 years), who are vulnerable to weight gain. This age group experience critical life course points (leaving home for higher studies or job, pregnancy, cohabitation) and develop/establish lifestyle and behavioural patterns making this an opportune intervention period. Medline, Embase, Cinahl, PsychINFO and Cochrane Library were searched (1980 to March 2008). All trials and cohort studies with control groups that assessed weight loss interventions in this specific age group were included finally identifying 14 studies. Before and after comparison of behavioural/motivational interventions (-2.40 kg; 95% CI -5.4 to 0.6) and combination interventions (-2.96; 95% CI -4.4 to -1.5) consistently showed weight loss. Behavioural/motivational interventions increased self-efficacy, the desire to control weight, boosted self-esteem, and increased satisfaction with body areas and appearance. Interventions also showed improvements in HDL cholesterol, insulin, glucose and maximum oxygen uptake. However, recruitment to participation in interventions was a barrier for this age group with small sample sizes and short-term interventions. There may be gender differences in preference to participation in certain type of interventions. Further research to understand attitudes towards healthy lifestyle and preferences of interventions is needed to develop suitable interventions for this vulnerable age group.