Bariatric surgery is currently considered the most effective treatment for long-term weight loss, reducing the burden of comorbidities and mortality in patients with severe obesity. However, it may also lead to new clinical challenges, complications, and side effects, particularly in the nutritional realm. Therefore, the nutritional management of bariatric patients requires specialized skills. This article provides an overview of the nutritional management of bariatric patients, from the preoperative to the postoperative phase, focusing on the initial diet stages.
Pre-operative Nutritional Considerations
Before bariatric surgery, it is essential to assess the nutritional status of candidates. Patients with severe obesity often exhibit micronutrient deficiencies compared to individuals of normal weight. Studies have shown that obese patients may have lower concentrations of vitamins A, B6, C, 25-hydroxyvitamin D, and lipid-standardized vitamin E. Deficiencies in iron, folate, and vitamin B12 are also common. These micronutrient deficiencies could be attributed to a poor-quality, non-varied, high-calorie, and high-fat diet. Therefore, nutritional status should be checked in every patient, and any deficiencies should be corrected before surgery.
Pre-operative Weight Loss: Is It Necessary?
The necessity of preoperative weight loss before bariatric surgery remains a topic of debate. Current guidelines do not provide clear indications for preoperative weight loss, likely due to the limited evidence available. Some studies suggest that a modest weight loss of 5-10% in the immediate preoperative period could facilitate surgery and reduce the risk of complications.
Very low-calorie diets (VLCD) and very low-calorie ketogenic diets (VLCKD) are the most frequently used methods for inducing preoperative weight loss today. Preoperative weight loss can be obtained with several regimens, such as low-calorie diets (LCD) (800-1200 kcal/day), very low-calorie diets (VLCD) (600 kcal/day), or a hypocaloric diet combined with IGB placement, and the question of which method provides the best results in terms of weight loss and patients’ compliance, tolerance, and acceptance is still under debate. A preoperative VLCD may also induce a significant weight loss before BS, being faster, cheaper, and with fewer side effects than IGB.
Post-operative Diet Stages
The first several weeks after weight-loss (bariatric) surgery are an important time. As your body heals, you move from a liquid diet to pureed and soft foods. This gives your body a chance to adjust to the changes created by the surgery. This short-term diet takes you through the first 4 to 6 weeks right after weight-loss surgery. It helps you gradually ease back into eating solid foods. The diet described here is used after the most common types of weight-loss surgery, sleeve gastrectomy and gastric bypass. After surgery, nutritional counseling is recommended to facilitate the adaptation of eating habits to the new gastrointestinal physiology.
Read also: Diet Before Bariatric Surgery
A gastric bypass diet follows a staged approach to help you ease back into eating solid foods. How quickly you move from one step to the next depends on how fast your body heals and adjusts to the change in eating patterns. It's important to get adequate nourishment while keeping your weight-loss goals on track. The bariatric surgery diet has several stages, each designed to support where you are in your healing. Each stage has its recommended foods, goals, and tips to help you avoid complications and reach your personal health and weight loss goals.
Stage 1: Clear Liquid Diet
While you are in the hospital, for the first 24-48 hours after surgery, you will be on a bariatric clear liquid diet. This stage usually begins within hours after surgery. This diet is designed to keep you hydrated without stressing out your stomach. At this time, you may be nauseous and fill up quickly. For the first day or so after surgery, you'll only be allowed to drink clear liquids. Examples are water, clear broth, and unsweetened decaf tea. That means anything translucent is acceptable except for sugary, alcoholic and carbonated drinks, of course. The goal during this period is to keep you hydrated. All foods have some degree of water content and since you will not be eating anything solid you have to drink more fluid than you normally would. Don’t drink your entire days’ worth of fluid right away. Take frequent, small sips rather than trying to drink a lot at once. Sip your fluids consistently, all day long to remain hydrated and balanced.
Stage 2: Full Liquid Diet
Once you are discharged from the hospital or on day 2-3 after surgery, your diet should be advanced to a bariatric full liquid diet. You will usually remain on this diet until day 15 (week 3) after surgery. This diet is designed to keep you hydrated and start to provide more nutrition (protein) for healing. After the first few days, you will be able to transition into a modified liquid diet. Again, you will be avoiding any high sugar, alcoholic and carbonated drinks - these are bad for your stomach pouch and your diet. This liquid diet will expand your options dramatically. Examples are plain low-fat yogurt, low-fat or skim milk, and diluted 100% fruit or vegetable juice. Your dietitian may also recommend protein shakes or other drinks with added protein. You’ll be able to drink low fat milk and protein shakes to boost your protein intake. You’ll also be able to drink some diluted fruit juices, broths, soups and more. You may also continue to consume clear liquids in addition to the suggestions below. Sip drinks frequently throughout the day. Within several days, work up to at least 7½ cups (60 ounces) of fluid daily to prevent dehydration. Yogurt (plain, no fat).
*A quick note on soups. All soups must be strained or blended to remove any chunks. Canned soups tend to be very high in sodium and calories. Please check the nutrition label carefully before choosing your soup. Ideally, make your own soup with fresh ingredients from the produce department.
*An important note on artificial/no-calorie sweeteners: You can consume artificially sweetened drinks during this time. They will likely make bland drinks more tolerable. However artificial sweeteners have no nutritional value and may make it harder to lose weight.
Read also: Bariatric Surgery Outcomes
Stage 3: Pureed Diet
At this point, you can tolerate slightly larger portions and are ready to start eating a bariatric pureed diet. About 10 to 14 days after surgery, your dietitian may tell you to add foods you can eat without chewing. The food will need to be blended/pureed to the consistency of baby food. This will allow you to build up tolerance to solid food. That includes foods such as applesauce and soup with no chunks of food. It also includes foods that have been pureed. This means processed in a blender until smooth. High-protein foods that can be pureed include lean meats, poultry, fish, and cooked eggs. To get enough protein, you may need to keep using protein shakes or powder as well. Other foods that can be pureed include soft-cooked vegetables and soft, skinless fruits.
Stage 4: Soft Foods Diet
After a few weeks of pureed foods, and with your doctor's OK, you can add soft foods to your diet. You will need to continue to focus on protein and will probably need to continue with the protein supplements to help meet your protein needs. After about a week on a pureed diet, your dietitian may tell you to add foods that can be mashed with a fork or don’t require much chewing. Now that you can tolerate food, you can continue to advance textures to a bariatric soft diet. The food will need to be chopped, ground, mashed, flaked, or pureed. These foods will require less chewing, passing more easily through your gastric pouch. Have 3 to 5 small meals or snacks per day. Include protein-rich foods each time you eat. High-protein foods that are soft include finely chopped or ground meat and poultry, flaked fish, soft-scrambled eggs, cottage cheese, soft-cooked beans, and soft tofu. Other soft foods include soft-cooked vegetables (no peel), cooked cereal, soft fruits (no skin or seeds), and canned fruit (in its own juice). You can eat 3 to 5 small meals a day. Each meal should consist of one-third to one-half cup of food.
Stage 5: Regular Foods Diet
At week 7, you are now ready to advance to regular textures and reintroduce a greater variety of food into your diet. After about eight weeks on the gastric bypass diet, you can gradually return to eating firmer foods. This is the diet that you should follow for the rest of your life. Start with eating three meals a day, with each meal consisting of 1 to 1-1/2 cups of food. Depending on how you tolerate solid food, you may be able to vary the number of meals and amount of food at each meal. You will still need to focus on protein but can start relying more on food sources of protein than protein supplements. You should continue to focus on protein and avoid high-fat or sugar-sweetened foods. Try new foods one at a time. Make sure that you eat slowly, listen to your body, and stop eating when you are full.
General Dietary Recommendations After Bariatric Surgery
Regardless of the specific stage, several general dietary recommendations apply after bariatric surgery:
- Eat and drink slowly. To avoid dumping syndrome, take at least 30 minutes to eat your meals and 30 to 60 minutes to drink 1 cup of liquid.
- Keep meals small. Eat several small meals a day. You might start with six small meals a day, then move to four meals and finally, when following a regular diet, three meals a day.
- Drink liquids between meals. To avoid dehydration, you'll need to drink at least 8 cups (1.9 liters) of fluids a day. Don’t drink anything from 30 minutes before a meal until 30 minutes afterward. Have liquids between meals, not with meals.
- Chew food thoroughly. The new opening that leads from your stomach into your small intestine is very narrow and can be blocked by larger pieces of food. Blockages prevent food from leaving your stomach and can cause vomiting, nausea and abdominal pain.
- Focus on high-protein foods. Always eat the protein first.
- Avoid foods that are high in fat and sugar.
- Take recommended vitamin and mineral supplements. After surgery your body won't be able to absorb enough nutrients from your food. Supplementation after weight loss surgery is a very important part of your health and successful resolution of weight-related diseases.
Potential Complications of Not Following the Diet Properly
The greatest risks of the gastric bypass diet come from not following the diet properly. If you eat too much or eat food that you shouldn't, you could have complications.
Read also: Is Bariatric Surgery Right for You?
- Dumping syndrome. If too much food enters your small intestine quickly, you are likely to experience nausea, vomiting, dizziness, sweating and diarrhea.
- Dehydration. Because you're not supposed to drink fluids with your meals, some people become dehydrated.
- Constipation.
- Blocked opening of your stomach pouch. Food can become lodged at the opening of your stomach pouch, even if you carefully follow the diet. Symptoms of a blocked stomach opening include ongoing nausea, vomiting and abdominal pain.
- Weight gain or failure to lose weight.
The Importance of Supplementation
Nutritional deficits may arise according to the type of bariatric procedure and they should be prevented, diagnosed and eventually treated. The degree to which you will have to supplement your diet with vitamins and nutrients largely depends on the procedure that you undergo. No matter the procedure, you will have to supplement, to a degree, immediately after surgery as you will be on a modified and restricted diet. Gastric bypass patients will require the greatest degree of supplementation of any of the major bariatric procedures. This is because of the malabsorption due to bypassing part of the small intestine. Since the walls of the small intestine are very sensitive and therefore absorb nutrients, vitamins and calories, shrinking the surface area available drastically reduces nutritional absorption. This means that gastric bypass patients are more prone to nutritional deficiencies than are those who have undergone purely restrictive procedures such as gastric sleeve and gastric banding. The supplements that are most often needed are› Protein - you will have many protein options after surgery. Each of these nutrients has very specific functions in the body and a deficiency in any one of them can cause a host of other problems. As an example, one of the most important nutrients - protein - is necessary for healing and also allows a patient to lose more weight because its density makes it harder to digest. Because most bariatric procedures severely restrict food consumption,it becomes very difficult for the patient to eat enough protein through their diet alone. Most often, patients will turn to protein shakes to fill the gap.
After any weight loss surgery, patients will need to take over the counter vitamins and minerals for life. Each bariatric surgery program will instruct patients on how much to take. These typically include: a multivitamin, Vitamin B12, Calcium, Vitamin D, and Iron. Some patients will need chewable vitamins, but some can take pills if tolerated.
Lifestyle Changes After Surgery
Patients who have chosen to undergo a major surgical procedure to make themselves healthier need to quit smoking for the rest of their life. Most bariatric surgery programs will require patients to stop all nicotine products before surgery. Alcohol use after bariatric surgery can have serious consequences. Alcohol is absorbed more quickly into the blood stream after surgery, and bariatric surgery patients will have higher levels of alcohol in their system for a longer period of time after drinking compared to before surgery. Female patient should have a birth control plan before surgery and avoid pregnancy for 12 to 18 months after surgery.
After weight loss surgery, patients often feel they have more energy and may want to exercise. Walking frequently, starting within just a few hours after surgery, can help patients recover faster. Each patient will be different and should check with their surgeon before they start intense exercise, but once this is started, it should be done with the goal on average to 30 minutes per day of moderate exercising.
Many bariatric patients are already taking several medications for their medical problems. After surgery, patient will often be able to be taken off certain medications or their dosages will be decreased. These decisions will be made with the patient’s primary doctor and their surgeon. Some patients will need different forms of medications if they are taking extended-release drugs, and some will need adjustments in dosages very early after surgery. Changes such as liquid or chewable medications may be needed, and these should be done under the direction of a doctor or pharmacist.