Bariatric surgery is an effective treatment for individuals who need to lose significant weight. 

However, surgery alone is not enough to solve obesity. Patients must follow dietary and behavioral guidelines after discharge to readjust their stomachs to food and prevent complications. 

Bariatric Surgery: Preoperative Diet

Before undergoing bariatric surgery, patients must undergo preoperative optimization, which includes losing weight, controlling comorbidities (such as high blood sugar or hypertension), and quitting smoking. Preoperative optimization is crucial because it reduces the negative effects of obesity on the postoperative course. Several studies have shown that a 10% weight loss can facilitate the surgical procedure and lead to better long-term outcomes in terms of weight loss, patient motivation, and adherence to the treatment course.

If necessary, a dietary protocol – such as a ketogenic or hypocaloric diet – should be prescribed by the medical team for a short period and under close monitoring. This is usually recommended for patients with a BMI over 50.

Reintroducing Food After Surgery

Within 24 hours after surgery, patients are advised to sip clear liquids gradually. Short-term nutritional rehabilitation is essential during the first month after surgery to reduce the risk of postoperative complications. Patients typically follow a liquid diet consisting of water, tea, herbal teas, clear juices, yogurt, and broths at room temperature during this period. 

In the second phase, a semi-liquid/creamy diet based on homogenized and smoothie foods is introduced until the surgical wound has healed, usually taking a month or so. Only after this “weaning” period has the stomach fully recovered and is ready to receive solid foods.

Nutritional Advice

Bariatric surgery should not be viewed as a quick shortcut but rather as a means to achieve lasting change. Patients should start to adopt healthier eating habits, such as planning daily meals, eliminating certain foods and carbonated/sweetened drinks, and chewing slowly. In the medium to long term, patients should continue to acquire healthy eating behaviors through regular nutritional follow-up visits and improve their lifestyle.

To avoid discomfort (such as nausea and vomiting) and maintain long-term results, patients are encouraged to follow specific guidelines, such as:

  • Chewing small volumes of food carefully
  • Devoting an adequate time to meals (20-30 minutes)
  • Splitting their diet into three main meals and two small snacks
  • Drinking 30 minutes apart from main meals

Avoiding Weight Regain in the Long Run

Factors that may predispose patients to regain some of the weight lost include consuming high-calorie foods, being sedentary, and resorting to emotional eating during particularly stressful events. Scientific studies show that five years after bariatric surgery, it is possible to maintain an excess weight loss of more than 50%.

Keeping body weight under control, establishing a weight range within which to settle, having regular follow-up visits, establishing constant contact with the medical team, recording progress, increasing consumption of fruits and vegetables, limiting consumption of sweets, alcohol, and hidden fats, and exercising regularly are all critical to a lasting recovery from obesity.