One hundred sixteen women participated in a 10‐week weight reduction program and lost on the average of 7 kg. Family‐related variables and two personality constructs, self‐esteem and Internal‐External Locus of Control (I‐E Loc), were examined as predictors for success in weight loss. Principal findings were: (a) Subjects with low self‐esteem scores lost significantly less weight than subjects with medium and high scores (4.3 kg vs. 8.7 and 6.4, respectively); (b) No significant differences were recorded between Internals and Externals with regard to weight reduction; and (c) Family‐related variables, marriage and number of children, did not directly affect weight loss, but their effect was observed within the three self‐esteem and the two I‐E Loc groups.