Nutrition 411: Obesity, Bariatric Surgery, and Wound Healing
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Obesity rates are rising at an alarming rate and pose a major public health concern in the US and worldwide. The Centers for Disease Control and Prevention1 estimate that 34% of the American population is obese, numbers that have trended upward dramatically since 1980. Even more alarming is the increase in childhood obesity. Obesity in children 2 through 19 years of age has steadily grown; currently, more than 17% of American children are obese.2
Obesity is defined by body mass index (BMI) ≥30, calculated by dividing weight in kilograms by height in meters squared. Morbid obesity is defined as having a BMI ≥40. Obesity is a refractory and multifactorial disease associated with many comorbid conditions that affect all organ systems (see Table 1). If comorbid conditions associated with obesity are taken into account, obesity contributes to an estimated 300,000 deaths per year.3
Conventional forms of obesity treatment include a combination of diet therapy, physical activity, pharmacotherapy, and behavior modification; the surgical approach (ie, bariatric surgery) is considered an effective long-term treatment.4 Because bariatric surgery successfully resolves certain comorbid conditions such as diabetes, hypertension, and obstructive sleep apnea, bariatric surgery is recognized as a metabolic surgery.5
Nutritional Concerns With Bariatric Surgery
Bariatric surgical techniques have evolved since the first surgical procedure (the jejunoileal bypass [JI]) was performed in the mid-1950s. According to the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK),6 the most common bariatric procedure performed in the US is the Roux-en-Y gastric bypass (RNYGBP), followed by the adjustable gastric band (AGB), vertical sleeve gastrectomy (VSG), and the biliopancreatic diversion with duodenal switch (BPD/DS). All bariatric procedures restrict stomach capacity, so the patient is unable to eat large portions of food, leading to weight loss because of reduced caloric intake. Some surgical procedures are also malabsorptive, so calorie and nutrient absorption is reduced, which also facilitates the weight loss process.
Thus, bariatric surgery poses challenges and opportunities for nutrition and healthcare professionals. The type of bariatric procedure has a bearing on the type of nutritional side effects or potential deficiencies that may develop. Currently, no single, standardized bariatric diet is available, and many recommendations are based on experiential data with limited evidence-based research. Most dietary recommendations for postbariatric surgical patients are supported by evidence for similar gastrointestinal surgeries or recommendations for very low-calorie diets (VLCD). However, the American Society for Metabolic and Bariatric Surgery (ASMBS)7 recently published specific guidelines for the perioperative and postoperative care of the bariatric patient.