OBJECTIVE:: To examine behavioural characteristics of subjects with successful long-term weight reduction. DESIGN:: Prospective cohort study with 3 y follow-up. SETTING:: Multicentre study of participants of a commercial weight-reduction programme (BCM-Programme). SUBJECTS:: Until February 2000, 6857 voluntary study participants were included. Analyses are based on 1247 subjects with complete 3 y data. INTERVENTIONS:: Open-group dietary and behavioural counselling with initial meal substitutions. RESULTS:: Subjects show a number of significant behavioural improvements, for example, choice of low-fat food, flexible control of eating behaviour and coping with stress. Subjects who maintain these changes by the end of the first year have a higher probability of successful weight reduction after 3 y. CONCLUSIONS:: Successful weight maintenance is associated with more pronounced improvements of health behaviours after 1 y. The likelihood of success increases with the number of behavioural patterns which are involved in the process of change.