Nutrition-wise blog

Why diet still matters after bariatric surgery

By Jennifer K. Nelson, R.D., L.D. March 1, 2017

I was recently asked why diet is important after bariatric surgery. At first I was confused by the question, but then I asked for and received this clarification: "If surgery corrects the weight problem, shouldn't it also compensate for overeating and indiscretions in food selection?"

The short answer is no. Here is a bit of background about bariatric surgery and why diet plays an important role.

Bariatric surgery includes a variety of procedures that alter the digestive track in ways that aid weight loss. Some bariatric procedures make the stomach smaller (between the size of a walnut and a small banana), thus restricting the amount of food that can be eaten.

Other surgical procedures change the length of the small intestine and the way food travels through it, which reduces absorption of calories and nutrients. Some procedures alter both the stomach and small intestine.

Because bariatric surgery changes the size of the stomach and way the small intestine digests food, you will lose weight. However, these changes also reduce your body's ability to absorb various nutrients.

Because you don't live on calories alone, short- and long-term nutrient deficiencies can develop. It's also possible to "undermine" your surgery with inappropriate food choices that can slow weight loss — or even lead to weight gain.

For all of these reasons, permanent dietary changes are needed after bariatric surgery. Here's what your diet might look like following surgery:

  • A liquid diet is recommended for the first week or two after surgery. A liquid diet (no caffeine, no added sugar, no carbonation) keeps you hydrated and provides some calories. A daily goal of 64 ounces (8 cups) will help prevent dehydration. It's important to remember that you may only be able to tolerate a few ounces of liquid at a time, sipped slowly. It's best to start with clear liquids and then move to full liquids (those that include low-fat milk).
  • Pureed foods are introduced after the liquid diet. Pureed foods have the consistency of a smooth paste with no distinct pieces. Food should be low in fat and without added sugar. Three to 6 small meals daily are encouraged. Each meal should be 2 to 3 ounces in size. Lean protein is emphasized for healing. This diet should be followed for 3 to 4 weeks. Drink liquids (no caffeine, no added sugar, low-fat, no carbonation) between instead of with meals to help prevent "dumping syndrome" (nausea, diarrhea, sweating, dizziness, weakness, rapid heartbeat).
  • Very soft foods (moist and tender foods, mashed or ground) come next. They must be low in fat and without added sugar. Food needs to be thoroughly chewed to ensure a pureed consistency before swallowing so that it can easily pass through the opening from the stomach (about the diameter of a pencil). Three to 5 small meals a day are recommended, with each being 3 to 4 ounces (6 to 8 tablespoons).
  • Soft chopped and diced foods that are tender and easy to chew are then added. Three to 4 small meals a day are recommended, with each being 4 to 6 ounces. Lean protein is emphasized. Beverages (no caffeine, no added sugar, low-fat, no carbonation) should be consumed only between meals. This diet is typically followed for 4 weeks.
  • Foods of any consistency from all the major food groups can be eaten once you're healed, about 3 months after surgery. Meals should still be 4 to 6 ounces. It's important to continue to choose foods that are high-protein, low-fat and with no added sugar. Likewise, it's essential to chew food to a pureed consistency and to drink beverages (no caffeine, no added sugar, low-fat, no carbonation) between meals. These habits should continue lifelong.

Because bariatric surgery limits the types of foods you eat and the nutrients you can absorb, the quality of your diet is very important. You need to choose the right amounts and kinds of nutritious foods to stay healthy.

For the first three months after surgery, a multiple vitamin and mineral supplement will be recommended. You may also receive monthly vitamin B1-2 injections. Thereafter, you can switch to the specific vitamin and mineral supplement your doctor recommends.

Going to regularly scheduled appointments after surgery is important to ensure successful weight loss and good health. It's also important to work with a registered dietitian to learn how to eat in a new way to achieve and maintain weight loss and to feel your best.

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March 01, 2017