After Weight Loss Surgery

If you are contemplating weight loss surgery, you are probably looking ahead to the results and what to expect during recovery. Certain side effects occur because so much weight is lost in a short period of time. Some of these side effects are also seen in people who have lost a great deal of weight without surgery.

Learn more about life after your weight loss surgery at NYU Langone.

Gastric Band Adjustments

If you have gastric band surgery, band adjustments are critical to the success of your surgery. If your weight loss plateaus, or if you continue to be hungry after eating, your band needs tightening. This is a simple procedure that your surgeon or nurse can usually perform in our office. On occasion, this needs to be done in the radiology department.

If you've had LAP-BAND® surgery elsewhere and require an adjustment, we would be more than happy to take care of you. Please contact our office for more information.

Hair Loss

During the first six months after surgery, almost everyone who has weight loss surgery experiences hair loss or thinning. Hair loss is alarming, but it typically doesn’t lead to baldness and is reversible. When your weight stabilizes and you consume more protein, your hair grows back. Chemical hair treatments, such as straighteners and perms, should be avoided.

Nausea or Dumping Syndrome

Because your new stomach pouch is quite small, you cannot eat as much food as you once did. Therefore, if you get full but continue to eat, or eat quickly without chewing thoroughly, pain and vomiting are likely to occur. You have to learn to eat slower, to chew food thoroughly, and to stop eating when you feel full. 

Overeating or consuming concentrated sweets or carbohydrates can lead to nausea and dumping syndrome, which occurs when the contents of the stomach quickly enter the small intestines, causing profuse sweating, nausea, dizziness, palpitations, and weakness.

If you don’t have problems eating during the first month after surgery and then suddenly experience nausea or vomiting after eating or drinking, you may have developed a stricture, or narrowing, at the point where the stomach pouch connects with the small intestine. This can be serious—you should call your surgeon for further evaluation.

Nutritional Deficiencies

Nutritional deficiencies can occur, particularly in patients who have a gastric bypass or biliopancreatic diversion, which causes food to skip the duodenum—the section of the small intestine where most iron and calcium are absorbed. Left uncorrected, this can lead to anemia or osteoporosis, among other conditions. 

After a biliopancreatic diversion—which is designed to dramatically reduce nutrient absorption—patients have to take even greater care to avoid nutritional deficiencies. 

The good news is that these problems can be avoided by eating the correct foods in small amounts, taking daily vitamin and mineral supplements, and getting regular medical checkups that include blood testing.

Lactose Intolerance

After certain bariatric surgeries, lactase, the enzyme needed to digest milk and other dairy products, does not reach food in the usual fashion. Consequently, you may become lactose intolerant, leading to gas, cramping, and diarrhea. Try avoiding dairy products and switching to alternatives, such as soy milk, rice milk, or lactose-free milk such as Lactaid.

Changed Bowel Habits

Weight loss surgery can change your food intake as well as your digestion. Some patients experience constipation, which can be treated with a mild, natural stool softener or by simply drinking more fluids. 

After a biliopancreatic diversion or duodenal switch, patients may experience diarrhea. This is usually caused by having too much fat in the diet. If that is not the case, a small amount of pancreatic enzymes may be required to help your digestion, which can be prescribed by your surgeon.

Loss of Muscle Mass

Because you're consuming far fewer calories and less protein, your body burns other energy stores to maintain itself. Surprisingly, the body prefers to use protein-rich muscle for energy before it taps into fat. 

Therefore, your initial weight loss may come at the expense of your muscle mass. This is most common after a gastric bypass, sleeve gastrectomy, or a biliopancreatic diversion or duodenal switch. Fortunately, loss of muscle mass can be avoided by exercising every day and consuming more protein. 

We recommend both regular aerobic activity and weightlifting. These activities can be alternated, but should be done at least three times a week for 20 to 30 minutes, though daily exercise is ideal and should be your goal. Regular exercise increases fat burning, builds and tones muscle, and raises your energy level.


With any rapid weight loss, there is an increased risk of developing gallstones. About 1 in 10 people who undergo bariatric surgery ultimately need to have their gallbladders removed. 

At NYU Langone, we do not routinely remove gallbladders at the time of weight loss surgery because most people would have their gallbladders removed unnecessarily. 

Instead, anyone who still has a gallbladder at the time of gastric bypass or biliopancreatic diversion or duodenal switch surgery is prescribed a medication called ursodeoxycholic acid for six months, which prevents gallstones from forming. 

If your gallbladder still needs to be removed, it can be done laparoscopically at a later date.