Bariatric surgery is the most effective means of achieving sustainable weight loss for the morbidly obese but resultant gastrointestinal functional changes and altered diet may lead to a number of eating and nutritional problems. This audit was conducted to evaluate Guernsey outcomes in relation to UK national standards and to determine the adequacy of current dietetic provision. A postal questionnaire was sent to 177 patients. Sixty-eight responded (48 gastric bypass, 15 banding and five other procedures). Mean body mass index preoperatively was 44.2 (five had body mass index <35). Five respondents (7%) had received preoperative and 26 post-operative dietary advice. Only 12 (18%) received any dietetic follow-up. Only one patient had any psychological support. Mean maximal weight loss and regain was 42.7 kg and 4.5 kg, respectively. Micronutrient supplementation and monitoring was variable. Deficiencies of B12 (44%), iron (25%), vitamin D (10.2%) and folate (6.2%) were recorded. Problems with food intolerances were common and often protracted. The majority of respondents expressed satisfaction with the procedure, but many recognized that it had not solved their food-related issues. There was dissatisfaction with dietetic intervention. Overall, current treatment was shown to fall short of UK standards. A number of recommendations have been made to improve future outcomes, including re-audit and improved dietetic service provision.