vertical banded gastroplasty (VBG) and gastric bypass Roux-en-Y (GBP) are adjunctive to lifelong commitment to energy restricted diet in the attempt by the severely obese to lose weight and maintain weight loss. the outcome of 48 subjects (36 VBG and 12 GBP) is presented. 18 months nutritional counseling and follow-up indicated VBG and GBP to be equally effective in maintaining appreciable weight loss. Achievement of ‘functional weight’, such as minimum 50% loss of excess body weight for at least 12 months post-operatively occurred in the majority of patients. Excess weight loss by GBP and VBG was 77% and 54% respectively during the first 6 months, with 7-15% additional loss during the next 12 months. BMI decreased from an average 43 to 27 kg m⁻² after 12 months. During the first 3 months, energy intake was approximately 2930 kJ, increasing to ∼4605 kJ at 6 months, to ∼5860 kJ at 12 months and then stabilizing. Intake of ∼50% of the Recommended Daily Allowance (RDA) for most vitamins and minerals was reached. Haemoglobin, iron, folic acid and thiamin values were in the normal range for the entire 18 months follow-up, while serum vitamin B₁₂ levels decreased to deficiency levels during the same period. The pre-operative moderately elevated triglycerides, cholesterol, glucose and insulin levels returned to normal range, thereby alleviating the need for medication and reducing the risk of obesity-related morbidity. Most subjects were quickly satiated with small amounts of solid foods and did not report hunger feelings for the first 6 months post-operatively. The main significant changes in food preferences in the first 6 months were the decrease in starch-based products and the increase in semi-solid milk products and eggs. taken together these observations suggest that the subjects should be strongly advised to partake in structured counseling for an extended period of time.