Objectives: To evaluate changes in meal patterns and in obesity related risk factors after 1 year of treatment in obese men. Design: Data from two 24-h dietary recalls, performed at base-line and after 1 year of treatment, were related to changes in medical risk factors. Setting: Academic obesity unit. Subjects: Sixty-three men, aged 44 (eight) years (mean [SD]) and Base- line Body Mass Index (BMI) 37.4 (4.6) kg m-2, who had completed 1 year of treatment. The men were subdivided by tertiles according to weight change: tertile I (n = 21), mean +0.3 kg, tertile II (n = 21), mean -5.8 kg and tertile III (n = 21), mean -14.2 kg. Main outcome measures: Weight loss, changes in meal patterns and in obesity related medical risk factors. Results: The reported mean energy intake decreased after treatment in tertiles II and III by 700 (1300) kcal (P < 0.05) and 700 (900) kcal (P = 0.001), respectively. In tertile III the energy-% from fat decreased (P < 0.05) with a reciprocal increase in energy-% from protein (P < 0.05). The frequency of snacks of a low nutritional quality decreased (P < 0.01) in tertile III together with an increase in energy-% from 'hot meals of good quality' (P < 0.05). Obesity related risk factors (anthropometry, blood pressure, serum lipid concentrations, blood glucose and plasma insulin) improved in a beneficial way only in tertile III. Conclusions: The weight loss in the successful tertile III men was to a great extent explained by fewer low quality snacks but more energy from high quality meals. These changes reflected the behaviour modification strategy recommended.