Comprehensive management after metabolic surgery: diet, nutrition, and lifelong weight maintenance

While the safety and efficacy of bariatric surgery are supported by substantial evidence, patients may face new, unique, and multifaceted clinical challenges post-surgery. The potential risks associated with these issues necessitate lifelong, nutrition-centric, multidisciplinary follow-up and management of obese patients. This includes nutritional management and long-term dietary counseling requiring intervention from experienced nutritionists and dietitians with specialized nutritional skills. Follow-up should include screening for micronutrient deficiencies, monitoring bone health, and monitoring for nutrition-related noncommunicable diseases. Management should reinforce healthy post-operative eating habits, such as slow eating, portion control, and meeting protein requirements.

Postoperative short-term dietary transition: Most bariatric surgeries involve reducing stomach capacity and/or creating gastric pouches, making it difficult to ingest solid foods on the first day after surgery. To avoid or reduce immediate postoperative reflux and vomiting (which can lead to surgical incision or anastomotic leakage or severe vitamin B1 deficiency), the transition should be gradual, with food textures changed gradually under the guidance of a nutritionist. Typically, the postoperative dietary transition plan begins with a low-sugar clear liquid diet within 24 hours post-surgery, then guides patients to gradually and sequentially change food textures over 24 weeks, progressing from clear liquids to soft or pureed foods, and finally to chewable solid foods. Patients should be trained to chew thoroughly and receive clear guidance on initiating and progressing their postoperative diet from an experienced obesity management nutritionist before discharge. Currently, most bariatric surgeries have corresponding dietary progression plans, which can be individualized based on regional or personal dietary preferences. After completing the short-term postoperative dietary transition, patients should receive regular nutritional counseling from a registered dietitian regarding long-term dietary changes to achieve the best results from the bariatric surgery and reduce the risk of long-term weight regain. The focus of dietary counseling should be on helping patients establish new eating habits to adapt to the surgical recovery process and to meet the principles of a healthy and nutritious diet. It is particularly important to emphasize that patients with limited stomach capacity should learn to eat "small meals" (which can be divided into 3-6 portions), chew food thoroughly before swallowing, and avoid drinking beverages while eating (with intervals of more than 30 minutes).

Protein intake and adequate supplementation are considered protective factors against lean body tissue loss during rapid weight loss in any situation. However, protein intake typically decreases after bariatric surgery. Studies have found that after all bariatric surgeries involving gastric capacity restriction, especially in the first few months following surgery when patients are prone to high-protein food intolerance, patients generally prefer low-protein foods. Usually, most food intolerance symptoms subside over time post-surgery, and protein intake tends to increase; however, even then, protein intake in the first year post-surgery may still be below the guidelines' recommendations, which is the period of most weight loss. Therefore, dietary counseling should focus on addressing protein intake issues, especially in the first month after surgery. Current Chinese guidelines for the surgical treatment of obesity and type 2 diabetes recommend a minimum daily protein intake of 60g/day, which can be as high as 1.5g/(kg·day) (based on ideal body weight), and higher protein intake may be required in individual cases.