Gastric Bypass

GASTRIC BYPASS DIET and BARIATRIC SURGERY FOR OBESITY

Discussion
Severe obesity (also referred to as morbid obesity) is a chronic condition that is very difficult to treat using traditional weight loss methods (1-2). Surgery to promote weight loss by restricting food intake or interrupting normal digestive processes is now recognized by the medical community as an effective medical option for severely obese people when other weight management approaches have proved unsuccessful (1-3). Bariatric surgery procedures promote weight loss by reducing the size of the gastric reservoir and/or causing malabsorption (1-3). Patients undergoing gastric bypass surgery must make the commitment to undergo medical monitoring for life.

The American Society for Bariatric Surgery has evaluated the various surgical options used in treating obesity over the last 30 years and have standardized these procedures with well-recognized and documented short-term outcomes (1,3). Bariatric surgery is an emerging field. The long-term health implications and nutritional consequences associated with rapid and substantial weight loss continue to require further study.

Indications
Criteria for surgical intervention for weight loss include (1-3):

A body mass index (BMI) greater than or equal to 40 with no comorbid conditions or health risk and acceptable operative risk.
A BMI of 35 or greater with comorbid conditions or health risks (eg, cardiopulmonary problems, diabetes mellitus, physical limitations), or a BMI of 40 or more and acceptable operative risks.
100 lb over ideal body weight with multiple unsuccessful attempts to lose weight using non-surgical methods.
Patient motivation and ability to comply to a lifelong program.

Bariatric surgeons use techniques that produce weight loss primarily by limiting the volume of food and fluid the stomach can hold. Restrictive procedures are often combined with modified gastric bypass procedures (eg, Roux-en-Y gastric bypass) to limit energy and nutrient absorption. Although anatomical changes are made during surgery, the patient who does not strictly adhere to the volume and types of food consumed can negatively affect the outcomes of the procedure. Consuming too high a volume of food can stretch the surgical pouch (pouch dilation), and eating high-energy low-nutrient quality foods can compromise the amount and rate of weight loss, thus defeating the intent and primary goal of the surgery. As in other treatments of obesity, successful results depend mainly on long-term motivation, adherence, and behavior modification strategies employed by the patient (1-3).

Two ways surgical procedures promote weight loss are by (2-3):

Decreasing food intake (restriction). Gastric banding (eg, vertical-banded gastroplasty [VBG], Silastic ring gastroplasty [SRG], and adjustable Silastic gastric banding [AGB]) are surgeries that limit the amount of food the stomach can hold by closing off or removing parts of the stomach. These operations also delay emptying of the stomach (gastric pouch). Regurgitation is a common side effect of this procedure.
Causing food to be poorly digested and absorbed (malabsorption). The most commonly performed and accepted gastric bypass procedure is the Roux-en-Y (3). In this procedure a surgeon makes a direct connection from the stomach to a lower segment of the small intestine, bypassing the gastric fundus, body, antrum, duodenum, and variable length of proximal jejunum. Symptoms associated with dumping syndrome such as tachycardia, sweating, and abdominal pain can occur with this procedure. Dumping syndrome occurs when stomach contents move too rapidly through to the remaining small intestine. In the more complicated bilio-pancreatic diversion (BPD) procedure the distal stomach, duodenum, and entire jejunum are bypassed, leaving only a 50-cm distal ileum common channel for nutrients to mix with pancreatic and biliary secretions. This procedure is a less preferred option because it substantially increases risk of nutritional and metabolic complications (3).

Rationale
The Gastric Bypass Diet and discussion on bariatric surgery is intended for severely obese patients specifically being treated for weight management. The primary outcome of the diet approach is to compliment the surgical procedure by promoting substantial weight loss through reduction in volume of food and energy intake. This diet is not intended for use for other types of gastric surgery, such as gastrectomy, that may be required for the primary treatment of other conditions or diseases (eg, cancer of the gastrointestinal tract, peptic ulcer disease, or trauma). Refer to Dumping Syndrome Diet or other Transitional Diets as needed.

Nutritional Adequacy
During the initial postoperative period (1 to 6 weeks), energy, protein, vitamin, and mineral needs are difficult to meet. However, the combination of diet and multivitamin supplementation can be planned to meet the Dietary Reference Intakes (DRIs), as outlined in the Statement on Nutritional Adequacy. The adequacy of the diet will depend on the type and extent of surgery and on postoperative progression of food based on the individual’s tolerance. Initially (up to 3 months postoperatively) deficiencies in protein and vitamin and minerals may occur (1). Due to the small volume of food consumed on the Gastric Bypass Diet, vitamin and mineral supplementation is necessary as an adjunct to the diet to meet specific vitamin and mineral needs. A multivitamin and mineral supplement regimen meeting 100% DRIs, including calcium, iron, and B12 should be consumed daily and considered necessary for lifelong maintenance of nutritional health for persons who have undergone gastric bypass surgery for weight loss (1,3). Chewable forms of supplements may be better tolerated in the initial stages after surgery (1-3).

How to Order the Diet
Order as “Gastric Bypass Diet.” One or more features of the diet may be individually ordered based on the postoperative stage, for example, Clear Liquids, Full-Liquid, Pureed, or Soft. Other modifications may need to be made to promote individual tolerance and weight loss, such as Lactose-Controlled Diet, Sugar in Moderation Diet, Low-Fiber Diet, Low-Fat Diet, or other strategies discussed under Planning the Diet.

Planning the Diet
Currently, limited scientific evidence is available to support specific guidelines and strategies for nutrition intervention following gastric bypass surgery for the treatment of severe obesity. Existing guidelines are based on emerging evidence reported by bariatric centers and institutions that specifically manage and treat gastric bypass for obesity long term. Current guidelines are based on available scientific evidence. See the discussion on Medical Nutrition Therapy Approaches to support this rationale.

Energy requirements: Total energy requirements will depend on the postoperative stage and volume of food tolerated. Ensuring nutrient quality is the primary goal when designing the meal plan:

25% or more of protein (or 72 to 80 g of protein per day) from total energy to minimize lean muscle loss during rapid weight loss. Protein modular supplements may be required during the first 6 postoperative months until solid food intake increase to meet requirements.
25% to 30% fat from total energy. Small amounts of dietary fat, along with prescribed medication, can be helpful in maintaining gallbladder emptying and can prevent risk of gallstone formation.
Approximately 50% from carbohydrate. Limiting intake of sugars is recommended for both types of gastric surgery procedures. Patients with gastric bypass generally do not tolerate sugars well, and consuming too much sugar can cause symptoms associated with the dumping syndrome. Patients with gastric banding procedures should avoid foods high in sugar. These foods often provide low-quality nutrients with high amounts of energy and fat, thus compromising the primary outcome of energy reduction to promote weight loss.
Once a diet of full liquids or semisolid food begins (usually 2 to 3 days postoperatively) initiate a chewable multivitamin/mineral supplement regimen providing 100% DRIs for age and gender. Additional specialized supplementation may be required for iron, calcium, vitamin B12, and folate (1) or other vitamins and minerals as indicated by laboratory assessment and based on ability to consume food sources (1).

Volume/consistency: Volume and consistency of foods consumed depend on the postoperative stage and individual tolerance. Initially the stomach can hold only 1 to 2 oz (2 to 4 tbsp). Over time, the stomach pouch will stretch until it can hold 4 to 8 oz or about ½ to 1 cup at a time.

Fiber: Foods high in fiber are generally not tolerated and should be avoided until the patient advances to a regular diet and tolerance is tested (usually >6 to 8 weeks postoperatively). Bulky foods such as bran, popcorn, raw vegetables, and dried beans should be avoided or limited based on individual tolerance as the diet progresses.

Fluid: At all stages, adequate consumption of fluids is essential to prevent dehydration. Fluids should add up to a minimum 6 cups (48 oz) per day. Once the patient is able to consume pureed or solid foods, fluids should be consumed 45 to 60 minutes before meals or after meals to prevent nausea and vomiting. Fluids should consist of water or controlled-energy (low-sugar, low-fat, or diet) beverages. Intake of caffeine-containing beverages and carbonated beverages may need to be limited based on individual tolerance.

Outcomes of Bariatric Surgery
Weight loss after bariatric surgery usually reaches a maximum between 18 and 24 months postoperatively (1). More than 90% of patients experience substantial (21% to 25%) weight loss, and between 50% and 80% of patients maintain weight loss for more than 5 years. In contrast, the 5-year efficacy of other weight loss approaches is approximately 5% (4,5). Mean percent excess weight loss at 5 years ranges from 48% to 74% after gastric bypass (Roux-en-Y) and from 50% to 60% after [VBG] (1). Weight reduction surgery has been reported to improve several comorbid conditions, such as glucose intolerance, and diabetes mellitus, sleep apnea, hypertension, and serum lipid abnormalities (1). A recent study showed that patients with type 2 diabetes treated medically had a mortality rate three times that of a comparable group who underwent gastric bypass surgery (6). Many patients report better mood, self-esteem, interpersonal effectiveness, and an enhanced quality of life after gastric bypass surgery for obesity (7).

The literature reports that the immediate operative mortality rate for both VBG and Roux-en-Y gastric bypass is relatively low (1,5). Morbidity in the early postoperative period (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). Emerging laparoscopic techniques provide a much safer mode of performing these procedures with less operative risks and quicker recovery periods. Results from laparoscopic surgery remain a subject for future outcome reports (1).

Types of Surgical Procedures
Restriction operations: Restriction operations for obesity include gastric banding, such as VBG, SRG, and AGB. These operations serve only to restrict food intake. They do not interfere with the normal digestive process. Restriction operations are the surgeries most often used for producing weight loss. Creation of a small pouch at the top of the stomach where the food enters from the esophagus restricts food intake. The pouch initially holds about 1 to 2 oz of food and expands to 4 to 8 oz with time (usually 6 to 9 months). The pouch’s lower outlet usually has a diameter of approximately ¼ inch. The small outlet delays the emptying of food from the pouch and causes a feeling of fullness. Restrictive operations lead to weight loss in almost all patients. However, some patients do regain weight (1). Approximately 30% of persons undergoing VBG achieve normal weight, and about 80% achieve some degree of weight loss (3).

After a restriction operation (>6 to 8 weeks), the patient usually can eat ½ to 1 cup of food without discomfort or nausea. Also, food has to be well chewed and consumed slowly. Most patients undergoing this surgery lose the ability to eat a large amount of food at one time, but some individuals do return to eating modest amounts of food without feeling hungry.

Types of restriction operations include (1):

Gastric banding: In this procedure, a band made of special material is placed around the stomach near its upper end, creating a small pouch and a narrow passage into the larger remainder of the stomach.
Vertical-banded gastroplasty (VBG): This procedure is the most frequently used restrictive operation for weight control. Both a band and staples are used to create a small stomach pouch.
Silastic gastric banding: Approved in 2001 for use in the United States, this operation is functionally similar to VBG. This procedure makes a small pouch out of the upper stomach. The pouch is stapled off from the rest of the stomach except for a small opening, which is then reinforced with a ring made of Silastic, a soft and rubbery but strong material.

A common risk of restrictive operations is vomiting. This occurs when insufficiently chewed food particles overly stretch the small stomach. Other risks of VBG include erosion of the band, breakdown of the staple line, and, in a small number of cases, leakage of stomach juices into the abdomen. The latter requires an emergency operation. In a very small number of cases (<1%), infection or death due to complications may occur (3).

Gastric bypass operations: Gastric bypass operations combine creation of small stomach pouches to restrict food intake and construction of bypasses of the duodenum and other segments of the small intestine to cause malabsorption. Gastric bypass operations that cause malabsorption and restrict food intake produce more weight loss than do restrictive operations that only decrease food intake. Patients who have bypass operations generally lose two thirds of their excess weight within 2 years. The risks of pouch stretching, band erosion, breakdown of staple lines, and leakage of stomach contents into the abdomen are about the same for gastric bypass as for VBG.

Types of gastric bypass operations are (1):

Roux-en-Y gastric bypass: This operation is the most common gastric bypass procedure. First, a small stomach pouch is created by stapling or by vertical banding. This step causes restriction in food intake. Next, a Y-shaped section of the small intestine is attached to the pouch to allow food to bypass the duodenum (the first segment of the small intestine) as well as the first portion of the jejunum (the second segment of the small intestine). This step causes reduced absorption of energy and critical nutrients.
Biliopancreatic diversion (BPD): In this more complicated gastric bypass operation, portions of the stomach are removed. The small pouch that remains is connected directly to the final segment of the small intestine, thus completely bypassing both the duodenum and jejunum. Although this procedure successfully promotes weight loss, it is not widely used because of the high risk of nutritional deficiencies (1).

Because gastric bypass operations cause food to bypass the duodenum, where most iron and calcium are absorbed, risks of nutritional deficiencies are higher in these procedures (3). Iron deficiency is common secondary to lack of contact of food iron with gastric acid and consequent reduced conversion of iron from the relatively insoluble ferrous to the more absorbable ferric form (1). Vitamin B12 deficiency may result from a multifactorial process including, food no longer coming in contact with gastric intrinsic factors, decreases in acid and pepsin digestion of protein-bound cobalamins from foods, and incomplete release of vitamin B12 from R binders (1). Vitamin D and calcium absorption may also be reduced since the duodenum and proximal jejunum, which are the preferential sites of absorption, are bypassed by this procedure (1). Anemia may result from malabsorption of vitamin B12 and iron in menstruating women, and decreased absorption of calcium may lead to the development of osteoporosis and metabolic bone disease (3). Shikora (8) reported nutritional consequences after gastric bypass surgery. Nutritional deficiencies that were reported include vitamin B12 (in 26% to 70% of patients), folate (in 33% of patients), and vitamin A (in 10% of patients); low serum potassium (in 56% of patients); and low serum magnesium (in 34% of patients). Patients are required to take nutritional supplements that usually prevent these deficiencies. Lifelong supplements of multivitamins, vitamin B12, iron, and calcium are mandatory following this procedure (1).

Gastric bypass operations also may cause the dumping syndrome. Symptoms include nausea, weakness, sweating, increases in heart rate and faintness. Occasionally, diarrhea occurs after eating or the patient is unable to eat sweets without becoming so weak and sweaty that he or she must lie down until the symptoms pass. Refer to the Dumping Syndrome Diet for appropriate medical nutrition therapy intervention and treatment.

Medical Nutrition Therapy Approaches
The more extensive the bypass operation, the greater the risk of complications and nutritional deficiencies. Patients with extensive bypasses of the normal digestive process require not only close monitoring but also lifelong use of special foods and vitamin and mineral supplementation. Surgery to produce weight loss is a serious undertaking. Each individual should clearly understand what the proposed operation involves. Patients, physicians, and the dietitian should together carefully consider the following benefits and risks (1-3):

Benefits:

Immediately after surgery, most patients lose weight rapidly and continue to do so until 18 to 24 months after the procedure (1). Although most patients then start to regain some of their lost weight, few regain it all (2-3).
Surgery improves most obesity-related conditions. Blood glucose levels have been shown to return to normal after surgery in 65% of obese patients with type 2 diabetes mellitus aged 45 to 71 years old (9). 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 requiring 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 (2,10). Gallstones are clumps of cholesterol and other matter that form in the gallbladder. During rapid or substantial weight loss, a person’s risk of developing gallstones is increased. Gallstones can be prevented with supplemental bile salts (eg, ursodiol) taken for the first 6 months after surgery (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 (11).
Nearly 30% of patients who have weight-loss surgery develop nutritional deficiencies such as anemia, osteoporosis, and metabolic bone disease (3). These deficiencies can be avoided if adequate vitamin and mineral intakes are maintained through lifelong supplementation.
Women of childbearing age should avoid pregnancy until their weight becomes stable, because rapid weight loss and nutritional deficiencies can harm a developing fetus. 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 (1,12).

Medical Nutrition Therapy After Gastric Bypass Surgery for Obesity
Currently, limited scientific evidence is available to support specific guidelines and strategies for dietary intervention following gastric bypass surgery for the treatment of severe obesity. Existing guidelines are based on emerging evidence reported by bariatric centers and institutions that specifically manage and treat gastric bypass for obesity long term. The current guidelines are based upon scientific evidence that is available. It is important to individualize the meal plan based on the postoperative stage and individual tolerance to volume and consistency of food.

Energy requirements: Objective estimation of required total energy is difficult to assess due to the rapid weight loss and rapid changes in fat-free mass to fat-mass ratio. One study evaluated changes in measured resting energy expenditure (MREE) after Roux-en-Y gastric bypass for severe obesity. The MREE was significantly less than the Harris-Benedict-predicted resting energy expenditure (REE) before the operation but rose to become equal to the Harris-Benedict-predicted REE by 6 weeks postoperatively and remained so during the evaluation period of 24 months (13). Patients who were hypometabolic before surgery (<15% MREE below Harris-Benedict-predicted REE) increased significantly despite reductions in energy intake (13). Energy intake was approximately 2,603 kcal/day before surgery for all subjects and fell to an average of 815 kcal/day at 3 months, 969 kcal/day at 6 months, 1,095 kcal/day at 12 months, 1,259 kcal/day at 18 months, and 1,373 kcal/day at 24 months postoperatively (13). Total energy requirements of the Gastric Bypass Diet will not meet predicted or measured energy requirements in most cases and will depend on the postoperative stage and volume of foods consumed by the patient. The goal of the diet is energy deficit to promote substantial weight loss. As energy increases, the rate of weight loss generally decreases or plateaus (1).

Protein: Most programs advocate for 25% or more of protein from total energy to minimize lean muscle loss during rapid weight loss and build new tissue after surgery to maintain lean muscle tissue long term (1). During energy restriction, it is generally recommended that patients consume 72 to 80 g daily of high-quality protein (14). Patients who ingest too little protein (<40 g/day) or consume protein that is mostly low biological quality are at risk of developing ventricular arrhythmias (15). Consuming adequate sources of high biological value protein at each meal and snack is suggested. Initially (1-2 weeks postoperatively), high-protein liquids such as no sugar added Carnation Instant BreakfastTM or EnsureTM can be used. Once solids are tolerated (generally 4 to 6 weeks) foods that are low in fat and high in protein such as lean red meat or pork, chicken or turkey without the skin, fish of almost any type, eggs, and cottage cheese are good sources. Protein modular supplements may be required during the first 6 postoperative months until solid food intake meets requirements, especially since meat and dairy consumption is one of the most frequently reported food intolerances after surgery (16). Symptoms for protein deficiency and protein-calorie malnutrition should be carefully monitored and evaluated. Hair loss is an indicator of inadequate intake of protein and can be a side effect of gastric bypass procedures (1). Refer to discussion on Medical Monitoring and Complications for additional information.

Fat: Approximately 25% to 30% of total energy should come from fat. Fat may be difficult to digest or tolerate after gastric bypass surgery, especially fried foods and snack foods. Steatorrhea is often a complication of the BPD procedure. Too much fat can delay gastric emptying and may cause reflux leading to heartburn. Small amounts of dietary fat consumed at each meal (approximately 10 g per meal) can be helpful in maintaining gallbladder emptying and prevent risk of gallstone formation(11). Long-term, a prudent low-fat diet should be advocated to sustain weight loss and reduce risk factors for other comorbid conditions(1).

Carbohydrate: Approximately 45% to 50% of total energy should come from carbohydrate. Carbohydrate can help prevent the loss of lean tissue (14). While carbohydrate intake does not have to be high, it is suggested that energy-restricted diets contain more than 100 g of carbohydrate per day to minimize ketosis (14). Hyperuricemia can also result from weight loss, particularly with the use of a low-carbohydrate diet. Ketone bodies, products of fat oxidation in the energy-restricted patient, compete with urate for tubular reabsorption in the kidney, resulting in elevated uric acid levels and predisposing the patient to gout. Increasing the carbohydrate content of the diet will reduce the risk of increasing uric acid levels (17). Limiting intake of sugars is recommended, as they generally are not tolerated and can cause symptoms associated with the dumping syndrome. In addition, sugary foods often provide low-quality nutrients and high amounts of energy and fat. Foods to avoid or limit include candy, cookies, ice cream, milkshakes, slushes, soda pop, sweetened juices or gelatin, and most desserts.

Fiber: Foods high in fiber are generally not tolerated and should be avoided until progression to regular foods has occurred (usually >6 to 8 weeks postoperatively). Bulky foods such as bran, popcorn, raw vegetables, and dried beans may need to be completely avoided. The newly created surgical pouch does not have the capacity to hold many of these foods. In addition, a reduction in gastric acid is available to help digest fibrous foods. Individual tolerance should be tested and evaluated.

Vitamins and minerals: Because the Gastric Bypass Diet allows only a small amount of foods and limits the types and variety of foods, vitamin and mineral supplementation is necessary. Once a full-liquid or semisolid food diet begins (usually postoperative day 2 or 3), it is suggested that a chewable multivitamin/mineral supplement providing 100% of the appropriate DRIs for the patient’s age and sex be initiated. For gastric bypass procedures (eg, Roux-en-Y and BPD), additional supplementation may be required for iron, folate, vitamin B12, and calcium (1), or other vitamins and minerals as indicated by routine laboratory assessment. Roux-en-Y and BPD procedures have a greater impact on nutrient absorption because of the anatomical alterations and impact on gastric acidity (16). It has been recommended to provide patients with prenatal vitamin and mineral supplements, which contain higher doses of iron and folate (16). Intakes of 40 to 65 mg of elemental iron (16) and 800 to 1,000 mg of folate per day have been recommended (16, 18). The use of sublingual vitamin B12 at an average daily dose of 350 μg/day has been shown to maintain adequate stores. Although this dose is 175 times the DRI, a small percentage of individuals will still become B12 deficient, requiring intramuscular injections on a monthly basis (16, 19). Calcium supplements of 1,200 to 1,500 mg/day should be provided to all patients (16). Calcium citrate with vitamin D is the preferred preparation because it is more soluble than calcium carbonate in the absence of gastric acid production (20). Calcium should be divided into doses over the day with no more than 500 mg/dose(16). For patients with the BPD procedure who have clinical steatorrhea, a high-dose calcium supplementation regimen (2,000 mg/day) along with a monthly intramuscular vitamin D injection is recommended to reduce the risk of metabolic bone disease (16).

Several studies have reported a significant correlation between eating habits (quality of food consumed) and laboratory values (1,21). In one study evaluating patients after a Roux-en-Y gastric bypass procedure, the mean serum iron saturation, vitamin B12, and folic acid were significantly higher in patients who ate meat than in patients who did not eat meat (21). Iron status continued to decline (6 to 8 years after surgery) depending on eating behavior (21). In this same study, oral vitamin and mineral supplementation significantly improved the nutritional status of the patients (21). Providing amounts greater than the recommended DRIs for vitamins and minerals has not been evaluated to assess benefits or improvements in nutritional outcomes following gastric bypass surgery.

Fluids: At all stages, adequate consumption of fluids is essential to prevent dehydration. Fluids should add up to a minimum 6 cups (48 oz) per day with a goal of consuming 64 ounces daily (18). It is recommended to initially consume 2 to 3 oz and increase fluid intake gradually to 3 to 4 oz at a time 8 weeks after surgery (18, 22-26). Once pureed or solid foods are introduced into the diet, fluids should be consumed 45 to 60 minutes before meals and should consist of water or energy-controlled (low-sugar, low-fat, or diet) beverages. Intake of caffeine-containing beverages and carbonated beverages should be individualized as tolerance may vary. Have the patient delay drinking beverages 45 to 60 minutes after meals to prevent increasing the transit time of food through the pouch, which may lead to nausea and vomiting. After 6 to 9 months, most patients can tolerate drinking fluids with meals.

Volume/consistency/timing: Volume and consistency of foods consumed depend on the postoperative stage and individual tolerance. Initially after gastric bypass surgery, the stomach can hold only 1 to 2 oz (2 to 4 tbsp). Over time, the stomach pouch will stretch until it can hold 4 to 8 oz or about ½ to 1 cup at a time. The Gastric Bypass Diet progresses in stages from clear liquids (1 to 2 days) to full liquids and pureed foods (4 to 6 weeks) and then to soft and regular foods (6 to 8 weeks). Patients vary on the timing of progression, so it is appropriate for individuals to adjust their own progress depending on how they feel. Four to six small meals per day may be better tolerated long term; however, coordinating with fluid intake may be challenging and should be individualized. After the pouch matures (6 months), most all consistency of foods can be tolerated. Refer to Table B-2: Guide to Choosing Regular Food After Gastric Bypass Surgery.

Food intolerances: Patient reports have indicated common intolerances to specific foods postoperatively (24-26). Among the foods most commonly reported as not tolerated include red meat, milk, and high-fiber foods. In one study, meat intolerance was observed in 51% of patients during postoperative months 0 to 12; 60.3%, at 13 to 24 months; 59.5%, at 25 to 72 months; and 55.1%, at 73 to 96 months (14). Soft breads are often not tolerated. However, crispy breads and crackers (eg, well-toasted breads, Melba toast, and low-fat crackers) are generally better tolerated. Milk intolerance may be a result of intolerance to fat or caused by a secondary lactose deficiency related to the surgical procedure (24-26). Fat-free milk in small amounts is suggested to improve tolerance. Overall, individual meal planning should be accommodated to meet nutrient-specific needs if foods are not tolerated.

Postoperative Meal Planning
The following meal planning and behavior modification recommendations should be given to the patient postoperatively. Individualization of the meal plan is important based on the postoperative stage and individual tolerance to volume and consistency of food (24-28). The following stages and meal patterns are based on a review of bariatric surgery programs (24-28):

Stage 1 (weeks 1 and 2)
Day 1 to 2: Clear Liquids

Provide 6 to 8 small feedings of clear liquid foods. Begin with sips of water, then add bouillon or clear broth, unsweetened juices, diet gelatin, and flat (no fizz) diet soda.
Portion: Sip 2 to 3 oz (1 to 2 tbsp) at a time.
Water: Sip of 2 to 3 oz at a time throughout day.
Combined 6 to 8 small feedings and water intake should be at least 48 oz/day (6 cups) to meet hydration needs.
If the patient tolerates the above well, progress to Full Liquids and Pureed (see below).

Day 3 to 4: Full Liquids

Provide 6 to 8 small feedings per day. Begin using high-protein liquids such as Diet Instant Breakfast (using fat-free milk), Glucera®, or specialized high-protein (low-fat, sugar-free) drinks. Gradually increase intake to 72 to 80 g of protein per day (14).
Portion: 2 to 3 oz (1 to 2 tbsp) at a time (may increase to 4 oz [6 to 8 tbsp] by week 2).
Water: Sip of 2 to 3 oz at a time throughout day.
Combined 6 to 8 small feedings and water intake should be at least 48 oz/day (6 cups) to meet hydration needs.
Begin a chewable multivitamin/mineral supplement to meet 100% DRIs for age and sex.
A full-liquid menu plan usually lasts 1 to 2 weeks postoperatively.

Stage 2 (week 2 to 3)
Week 2 to 3: Pureed/Soft Diet

Provide four to six small feedings of pureed or soft semisolid foods. Use high-quality protein foods such as scrambled eggs, Egg BeatersTM, low-fat cheese or cottage cheese, or blenderized lean meats such as tuna fish, chicken, or pork. Using strained baby foods is an option for convenience. Integrate a high-quality protein food with each meal or snack (20-22). Refer to Table B-1: Foods to Choose on a Pureed/Soft Diet After Gastric Bypass Surgery for Obesity.
Portion: 2 to 4 oz (4 to 8 tbsp) at a time of solid foods.
Alternate fluid intake with food intake, consuming fluids 45 to 60 minutes before and after consumption of solid foods. The combination of water with controlled-energy beverages and milk should equal at least 6 cups per day.
Behavior techniques need to be applied and reinforced (eg, eating small amounts, eating slowly, chewing food completely before swallowing)
At about 4 to 6 weeks, begin gradual introduction of soft to regular consistency low-fat, controlled-energy foods. The patient should keep a food record to document tolerance to foods to discuss with the dietitian during follow-up visits.

Table B-1: Foods to Choose on a Pureed/Soft Diet After Gastric Bypass for Obesity

Food	Choose	Avoid
Beverages	Crystal Light®, decaf coffee or tea, carbonated-free beverages, and high-quality nutrition drinks such as Glucera® or No-sugar added Diet Instant Breakfast, fat-free milk	Fruit drinks, iced tea with sugar, alcohol, soda and other carbonated beverages with high sugar content
Soup	Egg drop soup, reduced-fat cream soups, broth, and bouillon	All others
Breads/cereals/rice/pasta	Cooked, refined/strained cereals; mashed potato without skin Soft: add pasta, rice, toasted breads, melba toast, and crackers	All others
Vegetables	Pureed vegetables, vegetable juice Soft: add soft cooked vegetables	All others Soft: Vegetables with tough hulls or skins such as peas and corn
Fruits	Applesauce, pureed banana or other fruit without seeds or hulls, unsweetened fruit juice Soft: add soft unsweetened canned fruits or fresh soft fruits without skin or seeds	All others
Meat, protein, and protein substitutes	Pureed fish, tuna, poultry, veal, pork, or beef; low-fat cottage cheese, low-fat or nonfat cheese, baby-food meats (all types); mashed or pureed tofu, pureed egg or egg substitute Soft: add ground lean meat; fish or poultry; creamy peanut butter; casseroles made with ground meat and soft cooked vegetables; chopped tofu	Crunchy peanut butter, all others
Milk and milk products	Fat-free or 1% milk; sugar-free or low-fat yogurt (without fruit) Soft: add sugar-free or fat-free yogurt with fruit, low-fat, sugar-free frozen yogurt or ice cream	Chocolate milk, sweetened condensed milk; 2% or whole milk, ice cream
Others	Sugar free gelatin or popsicles; low-fat frozen yogurt, pudding or custard	All others

Adapted from Gastric Bypass—After Surgery. Healthy Directions Health Information from John Hopkins Bayview Medical Center.
Available at: www.jhbmc,jhu.edu/healthy/healthconditions/digest/gastricdiet.html. Accessed September 3, 2002.

Sample Menu: Stage 1: Full Liquid (Postoperative Week 1 to 2)

Time	Suggested Meal/Food
8 am	¼ to ½ cup unsweetened fruit juice
9-9:30 am	½ to ¾ cup fat-free milk with 1 package of Diet Instant Breakfast
11 am	¼ to ½ cup unsweetened fruit juice
12 pm	½ to ¾ cup cream strained low-fat soup
1-1:30 pm	½ to ¾ cup fat-free milk with 1 package of Diet Instant Breakfast
2 pm	½ to 1 cup water
3-3:30 pm	¼ to ½ cup of fat-free, sugar-free yogurt (may try 2-3 saltine crackers or melba toast)
5 pm	½ to 1 cup water
6-6:30 pm	½ to ¾ cup strained low-fat cream soup
7 pm	½ to ¾ cup fat-free milk with 1 package of Diet Instant Breakfast
8 pm	¼ to ½ cup sugar-free, low-fat pudding (may try 2-3 saltine crackers or melba toast)
9 pm	½ cup diet gelatin

Sample Menu: Stage 2: Pureed/Soft (Postoperative Week 2 to 3)

Time	Suggested Meal/Food
8 am	4 to 6 tbsp cooked refined cereal. Add 2 tbsp fat-free milk to thin cereal.
9-9:30 am	½ to 1 cup fat-free milk
11 am	3 tbsp low-fat cottage cheese, 1 tbsp unsweetened applesauce
12 pm	½ to 1 cup unsweetened fruit juice
1-1:30 pm	2 to 3 tbsp pureed ham, 2 tbsp mashed potatoes, 2 tbsp pureed broccoli
2 pm	1 cup water
3-3:30 pm	½ to 1 cup of fat-free milk with 1 package of Diet Instant Breakfast
5 pm	4 to 6 tbsp fat-free, sugar-free yogurt
6-6:30 pm	2 to 3 tbsp pureed chicken, 2 tbsp pureed carrots, 2 tbsp mashed potato with 1 tbsp fat-free gravy
7 pm	½ to 1 cup fat-free milk
8 pm	2 slices of fat-free or low-fat cheese, 3 to 4 tbsp pureed or finely chopped canned pears (in natural juice)
9 pm	1 cup low-fat cream soup or egg drop soup

Sample Menu: Stage 2: Soft (Postoperative Week 4 to 6)

Time	Suggested Meal
7:30 am	½ cup orange juice
8:15 am	Scrambled egg, 1 to 2 slices of toast, 2 tsp low-fat margarine
9:30 am	1 cup fat-free milk with 1 package of Diet Instant Breakfast
11 am	1 slice of cheese melted over 2 tbsp cooked pasta, 1 small soft cooked broccoli flowerette
11:45 am	½ to ¾ cup water
12:30 pm	3 tbsp flaked fish, 2 tbsp cooked, chopped spinach, 1 pear half
1:30 pm	½ cup orange juice
2:30 pm	½ to ¾ cup fat-free, sugar-free yogurt
3 pm	½ to ¾ cup water
4 pm	½ cup sugar-free, low-fat pudding
5:30 pm	1 cup fat-free milk
6:30 pm	4 tbsp diced chicken and rice casserole, 2 tbsp soft cooked green beans, 1 peach half (canned in natural juice)
8 pm	½ to ¾ cup water
8:30 pm	2 oz of tuna, 1 tsp low-fat or fat-free mayonnaise, 4 saltine crackers
9:30 pm	½ to ¾ cup water

Stage 3 (week 6 to 8)
Week 6 to 8: Regular Diet

Provide four to six small feedings of regular-consistency food. Use high-quality protein foods such as scrambled eggs, Egg BeatersTM, low-fat cheese or cottage cheese, or lean meats such as tuna fish, chicken, or pork. Refer to Table B-2: Guide to Choosing Regular Foods After Gastric Bypass Surgery for Obesity (26).
Portion: 4 to 6 oz (8 to 12 tbsp) at a time of solid foods.
Alternate fluid intake with food intake, consuming fluids 45 to 60 minutes before and/or after the consumption of solid foods. Combination of water with low-energy beverages and milk should equal at least 6 cups per day.
Behavior techniques need to be applied and reinforced (eg, eating small amounts, eating slowly, chewing food completely before swallowing).
The patient should keep a food record to document food intake and eating behavior, including foods tolerated or not tolerated to discuss with the dietitian during follow-up visits.

Sample Menu: Stage 3: Regular Diet (Postoperative Week 6 to 8)

Breakfast	Lunch	Dinner
Banana—¼ medium Scrambled egg—1 Toast, white—½ slice Margarine—1 tsp	Broiled chicken breast—2 oz Carrots, boiled—¼ cup Margarine—1 tsp Pasta salad—¼ cup	Haddock, baked or broiled—2 oz Green beans—¼ cup Dinner roll—½ Margarine—1 tsp

Morning Snack	Afternoon Snack	Evening Snack
Graham crackers—2 squares Pudding, sugar-free, made with fat—free milk—½ cup	Fruit cocktail, water packed —½ cup	Cheese, American—1 oz Saltine crackers—2 squares Mustard—1 tsp
*Consume fat-free milk between meals throughout the day. Drink approximately ½ to 3/4 cup at a time, for a daily total of 2 cups.

Sample Menu: Stage 3: Regular Diet—Nutrient Content Breakdown
Calories	1056	Fat	42 g
Protein	71 g	Calcium	1065 mg
Carbohydrates	97 g	Iron	6 mg

Table B-2: Guide to Choosing Regular Food After Gastric Bypass Surgery for Obesity

Food Category	Foods Allowed	Foods That May Be Difficult to Tolerate	Foods to Limit for Best Weight Loss
Beverages	Water, tea, club soda, diet soft drinks, coffee, fat-free milk	Milk may not be tolerated except for fat-free milk in small amounts. Use low-fat, or fat-free, sugar-free yogurt and cheeses for other sources of calcium.	High-energy drinks: whole milk, milk shakes, alcoholic beverages, sweetened fruit juices and drinks
Breads	Dry, coarse, or well-toasted bread; crispy crackers or baked tortilla chips	Soft breads that become gummy, breads with nuts, seeds, or dried fruit	Sweet breads, Danishes, and donuts
Cereals	All cooked and dried cereals without added sugar	Cereals containing dried fruit or nuts	Cereals with added sugar or providing >10 to 15 g sugar/serving
Potatoes, rice, pasta	Boiled, mashed, or baked potatoes; well- cooked pasta and rice	Potato skins, sweet potatoes, rice, noodles	None
Fruits	Fresh, canned, frozen, or cooked fruit. Be cautious with apples, grapes, other fruits with peel or skin.	Dried fruits; fruits with core, seeds, or skin; whole citrus fruits (eg, grapefruit, oranges). It is recommended that citrus fruits should be juiced.	None
Vegetables	Fresh, canned, frozen, or cooked vegetables	Vegetables with tough skins or seeds	None
Meats	All if diced to ¼ inch (size of a pencil eraser) and well chewed	Tough meats or those with gristle. Some patients do not tolerate red meat.	None
Dessert	Frozen yogurt, low-fat gelatin sherbet, fruit pies, low-fat, low-sugar pudding	Any dessert with nuts, dried fruit, seeds, or coconut; candy containing sugar, nuts, dried fruit, jams, or marmalade	All, except fresh fruit
Fats	All, in small amounts	Fried foods with a hard crusty coating	All
Miscellaneous		Soups with large pieces of meat; popcorn, nuts, chili, and other highly spiced foods. Avoid chewing gum.	Fried, salty snack foods; creamed soups unless made with nonfat milk

Source: Pilcher J and Surgical Consultants of San Antonio, Tex. Gastric bypass diet.
Available at: http://www.sabariatric.com/diet_plan.htm. Accessed September 3, 2002.

Strategies for Behavior Modification

Behavior modification is a critical element for short-term and long-term success following bariatric surgery, as it directly affects for the Gastric Bypass Diet. Behavior modification helps to improve tolerance during the initial postoperative stages. Continuing to apply behavior modification techniques as described below will also lead to improved weight loss outcomes long term (1,23-28).

The patient should eat slowly, chewing foods completely before swallowing. The suggested average time to complete a meal is 20 to 30 minutes (24-26).
The patient should drink low-fat, low-sugar beverages including water between meals, preferably 45 to 60 minutes before meals (24,26).
Portion control is very important. Foods should be cut, diced, and portioned to prevent overeating.
The patient should become aware of satiety sensations and signs of pouch fullness. A feeling of pressure or nausea after consuming a food or beverage is a sign that the pouch may be full. Avoid overeating, or eating until one “feels” full. There is a delay in response from when the pouch is full and when the brain signals fullness, so sticking with planned portions is important. Chronic overeating may cause pouch dilation and result in ineffective weight loss and premature weight gain (1,26).
If vomiting occurs after eating, the patient at the next meal should eat more slowly, properly chew food, and drink fluids 45 to 60 minutes before eating. Avoid overeating. Lying down after eating may be helpful (23-28). Prolonged (> 7 to 14 days) of reoccurring vomiting or intolerance to consumption of food should be immediately reported to the physician to prevent complications of malnutrition or dehydration. Refer to Specialized Nutrition Support.
Food intolerances are common. Having patients keep detailed food records is important in determining how to achieve a high-quality meal plan that integrates a variety of nutrient-dense foods.

Medical Monitoring and Complications
Close medical monitoring is critical during the acute (1 to 16 weeks) postoperative stages of weight loss to determine adequacy of nutritional intake, and determine the physiologic impact of rapid and substantial weight loss. Routine monitoring of vital signs (eg, blood pressure, heart rate), and laboratory assessment should be completed to assess the patients electrolytes, hydration and cardiac status. Risks associated with rapid weight loss include potassium loss as well as loss of body protein, which could lead to ventricular arrhythmias (15). However, it has been demonstrated that losses of body protein are less in the severely obese patient, which may protect the patient from arrhythmias during rapid weight loss (22). Due to low-energy intake during the initial stages of the Gastric Bypass Diet, urinary ketones are generally increased. Urinary ketones interfere with the renal clearance of uric acid, resulting in increased serum uric acid levels, which may lead to gout (17). Providing more than 100 g of carbohydrates per day may help minimize ketosis and uric acid levels (14). Higher serum cholesterol levels resulting from mobilization of adipose tissue may pose a risk of gallstones (23).

Patients who fail to modify their behavior and patients who have anatomical complications may experience constant postprandial vomiting. Because of a complete lack of nutrition, these patients can develop complications such as protein-calorie malnutrition and Wernicke-Korsakoff syndrome (16,18,19). There have been reports of a 3% to 5% incidence of hospitalization for treatment of protein-calorie malnutrition after BPD procedures (30). If prolonged vomiting occurs (>7 to 14 days), the patient should be clinically assessed and treated for dehydration and evaluated for enteral or parenteral nutrition support. Currently, limited scientific evidence is available to support specific guidelines and strategies for nutrition support following gastric bypass surgery. There have been clinical reports of patients receiving enteral feeding after gastric bypass surgery if their gastrointestinal tracts are functional. Enteral feedings can be provided using a small-caliber nasogastric tube placed into the distal stomach or remaining small bowel. An isotonic elemental formula given slowly with a pump over a 24-hour period may promote greater tolerance (29). With any feeding regimen, the clinician should be alert for refeeding syndrome (16,18,29) by carefully monitoring serum levels of phosphorus, potassium, and magnesium (18). If parenteral nutrition is indicated, it is recommended that the initial infusion contain only 50% of the estimated energy needs and 50% of the estimated fluid volume for the first 24 hours. Current literature often recommends administering hypocaloric feeding with adequate protein (18). (Refer to Specialized Nutrition Support for additional information on refeeding syndrome.) Patients who experience prolonged vomiting may develop acute neurological deficits 1 to 3 months after gastric restrictive surgery (16, 29). Symptoms of these neurological deficits include double vision, ataxia, nystagmus, bilateral facial weakness, acute polyneuropathy with paralysis, reduced deep tendon reflex, and mental confusion. Wernicke-Korsakoff syndrome related to thiamine deficiency has also been observed in this population. Patients who manifest neurological symptoms should be treated with 100 mg of thiamine that is intravenously or intramuscularly administered for 7 to 14 days, followed by oral administration of 10 mg of thiamine per day until the patient fully recovers (31).

References

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Bibliography
Brolin RE. Bariatric surgery and long-term control of morbid obesity. JAMA. 2002;288:2793-2796.

Food

Sample Menu: Stage 3: Regular Diet—Nutrient Content Breakdown

Food Category

Strategies for Behavior Modification

References