Long-term maintenance of weight loss is generally poor after clinical interventions, whether behavioural, cognitive-behavioural, dietary, pharmacological or surgical. This may be because self-assertion regarding body shape and self-efficacy in weight control are insufficiently encouraged in clients. Semi-structured group therapy sessions with written handouts were therefore designed to strengthen personal effectiveness and self-esteem. The therapy sessions also provided information about successful dieting behaviour, and encouragement of less switching between dieting strategies, less emotional eating, and more resistance to inappropriate social pressures. The clients were 24 women with a median (range) Body Mass Index of 28.9 (24.6–48.5) kg/m2, referred by their General Practitioners or self-referred. They participated in eight weekly therapeutic sessions in four groups and were followed up six months after the final session. There were large improvements during therapy in reported self-esteem, emotional overeating, personal effectiveness and self-efficacy, habit variation, and attitudes to body-size, improvements which were maintained at follow-up. In addition, there was a significant loss of body weight during therapy, with further loss observed at follow-up. Thus it is practicable to achieve marked reductions in professed problems with body image and eating control, changes that are theoretically necessary to empower clients to choose appropriate weight targets and to make progress towards them.