Gastric Bypass Surgery

When you swallow food, it will go into the small upper pouch of the stomach. This pouch holds only about one ounce of liquid or two to three small bites of food at a time. From the upper pouch the food passes through the half-inch opening (anastomosis) into the upper small intestine (jejunum).

Before surgery, your stomach broke up food so it could be digested. The new small pouch in your stomach will not do this. Instead, your small intestine will digest the food using enzymes (proteins) that are made by your other organs (the lower stomach, pancreas, and liver). Even though your body will absorb food normally, it may not absorb some vitamins and extended-release medicines (medicines that release into your body over time) normally.

For the first two weeks after surgery, you can only eat pureed food (liquified in a blender). After two weeks you can eat soft solid foods. Most patients can eat regular foods after one month. You must chew your food well before swallowing so it will pass easily into the small intestine.

Right after surgery, you will need to drink protein shakes that are low in fat and carbohydrates until you can eat enough solid protein. In the long term, you will need to avoid high calorie liquids because the surgery changes how your body digests sugary, fatty substances.

Before surgery, foods such as juice, milk shakes and cake were processed by the stomach before they entered the intestine. After surgery, food goes directly into the intestine, which can't process the fat and sugar.

This is called dumping. It can lead to feeling feel weak and sweaty. Dumping can cause diarrhea and a faster heart rate. Simply put, avoid foods that are high in sugar and fat after gastric bypass surgery.

The staples might leak: The surgeon will use staples on your stomach. A leak in the line of staples or one of the connections is a rare but serious problem that can happen in the first two weeks after surgery. If it does, you may need more surgery.

Your intestines might get blocked: During surgery, the surgeon cuts and reconnects your intestine. This forms open spaces behind the new connections. These spaces are closed during surgery, but if any open up over time, the intestine can move into the spaces and become blocked. This is rare and can happen years after surgery.

Bands of fibrous scar tissue called adhesions can form that can block your intestine. This may happen years after the surgery, and it can happen with any type of abdominal surgery.

Narrowing: The place where the stomach and intestine meet might become narrow, causing ulcers. This happens most often to patients who start smoking again or take anti-inflammatory drugs such as ibuprofen.

You could have low levels of some vitamins: All patients who have gastric bypass surgery need to take a multivitamin, vitamin B12 and calcium citrate. Some patients also need an iron supplement. If you don’t take these supplements, you’ll be more likely to have vitamin deficiency.  

If you adopt lifelong good habits in the first two years after surgery, you probably won’t regain much weight. At five to 10 years after surgery, patients have usually kept off 67% of their extra weight.

Studies have shown that between years two and six after surgery, patients may gain back 20% of the weight they have lost. If you continue appropriate eating habits, this weight gain may not occur. Studies have also shown that only 1% to 2% of patients gain back all the weight.

Your weight loss will be fastest in the first six months after surgery. After that, your weight loss will slow down. Two years after surgery, you might gain back some weight. The amount of weight you gain is different for every person. You might not gain any or you might gain all your weight back, but this is rare.

If you go back to bad habits, you’re more likely to regain some weight. Working closely with your health care team after surgery will help you continue to move toward your goals.