Nutrition Management in Bariatric SurgeryManual of Clinical Nutrition Management B- 21 Copyright © 2013 Compass Group, Inc.
and carbonated beverages may need to be limited based on individual tolerance.
Outcomes of Bariatric Surgery
Weight loss usually reaches a maximum between 18 and 24 months after bariatric surgery (1). More than 90%
of patients experience substantial (21% to 25%) weight loss, and between 50% and 80% of patients maintain
the weight loss for more than 5 years. In contrast, the 5-year efficacy of other weight loss approaches is
approximately 5% (2). Mean percent excess weight loss at 5 years ranges from 48% to 74% after Roux-en-Y
gastric bypass, from 50% to 60% after vertical-banded gastroplasty, and 50% following laparoscopic
adjustable gastric banding (1). Bariatric surgery improves several comorbid conditions, such as glucose
intolerance, diabetes mellitus, sleep apnea, hypertension, and serum lipid abnormalities (1). A 10 - year follow-
up study demonstrated that the excess weight loss of bariatric surgery patients remained within 14% to 25%
of the baseline weight loss (8). Adams et al demonstrated that after 7.1 years, the adjusted long-term mortality
decreased by 40% in patients managed with bariatric surgery (9).
The immediate operative mortality rates for the laparoscopic adjustable gastric banding procedure and the
Roux-en-Y gastric bypass are relatively low (8-10). Morbidity in the early postoperative period following Roux-
en-Y gastric bypass (eg, wound infections, dehiscence, leaks from staple breakdown, stomal stenosis,
marginal ulcers, pulmonary problems, and deep thrombophlebitis) may be as high as 10% or more (1).
However, the aggregate risk of the most serious complications of gastrointestinal leakage and deep venous
thrombosis is less than 1% (1,8-10).
Medical Nutrition Therapy Approaches in Bariatric Surgery
The risks of complications and nutritional deficiencies increase as the extensiveness of the bypass operation
increases (1). Patients with extensive bypasses of the normal digestive process require not only close
monitoring but also the lifelong use of special foods and vitamin and mineral supplementation (1,5). Before
any type of bariatric surgery, patients should have a comprehensive multidisciplinary screening, nutrition
assessment, and nutrition education to address the long-term plans for postoperative nutrition care and
weight loss strategies (1). Each individual should clearly understand the proposed operation. Bariatric
surgery is a serious undertaking. Patients, physicians, psychologists, and dietitians should together carefully
consider the benefits and risks during the nutrition assessment and evaluation period (1,2,4).
Benefits:
Immediately after surgery, most patients lose weight rapidly, and they continue to lose weight for 18 to
24 months (1). Although most patients then start to regain some of their lost weight, few patients regain it
all (1-3).
Surgery improves most obesity-related conditions. Blood glucose levels return to normal after surgery in
65% of obese patients aged 45 to 71 years old with type 2 diabetes mellitus (6). The American Diabetes
Association recognizes bariatric surgery as a viable option for patients with type 2 diabetes mellitus and
a BMI of at least 35 kg/m^2 who have poor control of symptoms. Patients also usually experience lower
blood pressure and lower serum cholesterol levels postoperatively (1).
Risks:
Of patients who have weight-loss operations, 10% to 20% require follow-up operations to correct
complications (2,3). Abdominal hernias are the most common complications that require follow-up surgery.
Less common complications include breakdown of the staple line and stretched stomach outlets (3).
Gallstones develop in more than one third of obese patients who have gastric surgery (2,11,12). Gallstones are
clumps of cholesterol and other matter that form in the gallbladder. During rapid or substantial weight loss,
the risk of developing gallstones is increased. Gallstones can be prevented by taking supplemental bile salts
such as ursodiol for the first 6 months after surgery (1,2). In addition, consuming dietary fat (approximately
30% of total energy or 10 g of fat per meal) can help maintain gallbladder emptying and decrease the risk of
gallstone formation (1,5).
Nearly 30% of patients who have bariatric surgery develop nutritional deficiencies such as anemia,
osteoporosis, and metabolic bone disease (1,3,6,7). These deficiencies can be avoided if adequate vitamin
and mineral intakes are maintained through lifelong supplementation.
Women of childbearing age should avoid pregnancy for at least 12 months perioperatively and until their
weight stabilizes, because rapid weight loss and nutritional deficiencies can harm a developing fetus (1).
Women who become pregnant after these surgical procedures need specific attention from the surgical
care team. There are several reports in the literature of pregnancy outcomes following gastric bypass
without evidence of fetal impairment (1,13).