Reduction of food intake is an important mechanism by which bariatric procedures reduce body weight. However, only few studies have systematically assessed what patients actually eat after different types of bariatric operations.

Dietary habits were assessed by a food frequency questionnaire in 121 bariatric patients (48 gastric bypass patients, 73 gastric banding patients) during follow-up visits in our interdisciplinary obesity center as well as in 45 severely obese (body mass index (BMI) > 35 kg/m²) and 45 nonobese (BMI < 27 kg/m²) control subjects.

As compared with nonobese control subjects, obese control subjects consumed more meat, white bread, and diet soft drinks. Gastric bypass patients showed an enhanced consumption of foods rich in protein such as poultry, fish, and eggs as well as of cooked vegetables, while the consumption of fatty sweets like chocolate, cake, biscuits, and cookies was found to be distinctly reduced in this patient group. In contrast, gastric banding patients reported on a reduced intake of pasta, white bread, and fresh fruits and, just like gastric bypass patients, also on an enhanced intake of poultry and fish. Direct comparison of dietary habits between the two bariatric patient groups revealed that gastric bypass patients consumed more frequently fresh fruits, eggs, and diet soft drinks but strikingly less chocolate than gastric banding patients.

Collectively, data clearly point to distinct changes in dietary habits after bariatric operations which markedly differ between gastric bypass and gastric banding patients. Overall, it is tempting to conclude that gastric bypass operations lead to a healthier and a more balanced diet than gastric band implantations.