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Using Whey and Soy Protein for Roux en Y Gastric Bypass Surgery Aftercare

By Edited Jun 25, 2015 1 2

Losing weight is difficult for many people; an almost impossible task for others which causes some to opt for surgery, the most common being roux en y gastric bypass surgery. When gastric bypass is opted, there are several requirements for aftercare; one of them is patients must ingest about 75 grams of protein daily.[3]  Proteins digest more slowly than carbohydrates and provide energy over a longer period of time.

An Overview of Roux en y Gastric Bypass Surgery

Roux en y Gastric Bypass surgery (RYGB) combines a restrictive procedure with a small amount of malabsorption. The stomach is divided and stapled into two sections. The upper tiny part receives food from the esophagus while the bottom part does not receive any food but continues to send stomach acid into the duodenum. The surgeon divides the small intestine and connects the small stomach pouch to the middle of the small intestine, called the jejunum, with an opening about the size of a dime between the two. The upper part of the small intestine, the duodenum, is completely bypassed as is the lower part of the stomach. The joining of the stomach and the jejunum is called an anastamois. The other end of the jejunum is reconnected creating a “Y.” Before surgery the majority of absorption is completed in the duodenum, but after surgery, since the duodenum is bypassed, the food actually begins absorption at this “Y.”

 Because the bottom of the stomach is bypassed as well as the duodenum, some supplements are required. In addition, the size of the new stomach pouch is reduced from about the size of a football to the size of an egg.[3]  That means a lot less food is tolerated at one time. The size of the opening means food needs to be chewed quite well so the opening does not get plugged. All this helps the individual lose weight; however, it is possible to “outsmart” the bypass surgery by eating or drinking high caloric foods and beverages and eating many meals during the day. Not following the after surgery nutritional plan can result in regaining the weight as well as other health issues.

Whey Protein is a Great Source of Protein for Gastric Bypass Patients

There are many protein sources available. Eggs, fish, beans, dairy and nuts are the most protein-rich foods.[3]  There are also numerous protein supplements such as powders, available on the market as well. Whey protein is a supplement often used by body builders, but it is a great source of protein for patients of gastric bypass surgery.

Whey protein is natural high quality protein that comes from milk; the byproduct when cheese is made. It is full of the essential amino acids the body needs. The purest form of whey protein, whey isolate, contains little or no fat, cholesterol or lactose. Whey is a soluble, easy to digest and is absorbed into the body quickly. Whey protein increases levels of glutathione, an anti-oxidant required for a healthy immune system in the body.

Whey can help weight management for several reasons. More energy is required to digest protein than other foods and therefore, more calories are burned to process a protein meal. It contains little or no fat or carbohydrates and helps to stabilize blood glucose levels. The absorption of glucose is slowed in the bloodstream which lowers insulin levels and reduces hunger. Whey protein also contains bioactive components that stimulate the release of two hormones that suppress the appetite.

Whey comes in the following three forms:[1]

  1. Concentrates which contain a low level of cholesterol and fat. They usually have higher levels of lactose and bioactive compounds. They are 29-89 percent protein by weight. They have a somewhat milky taste.
  2. Isolates which have the fat and lactose removed but are also usually lower in bioactive compounds. They are at least 90 percent protein by weight. These too have a slightly milky taste.
  3. Hydrolysates which are partially hydrolyzed, predigested and are more easily absorbed than the other two forms. These are the most expensive of the three types of whey protein and taste bitter.

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Soy Protein is Another Option for Patients of Gastric Bypass Surgery

Another possible source of protein for gastric bypass patients is soy protein. Soy protein is found in soybeans, contains no cholesterol and is low in saturated fat. Soybeans are considered a good source of iron, calcium, fiber, B vitamins and zinc and are the only vegetable that contains all eight essential amino acids.[3]

Common soy forms include tofu, soymilk, soy flour, textured soy protein, temeph, and miso. Soy proteins are divided into categories according to how they are produced. These categories are:[2]

  • Isolates which are the most refined form and are the proteins most often used in meat products to improve eating quality and texture. They contain about 90 percent protein.
  • Concentrates which are soybeans without the water soluble carbohydrates. They contain about 70 percent protein.
  • Textured soy proteins which are made from concentrates and then textured. They are often called TSP and are available in chunks or dry flakes. When hydrated, these soy proteins keep their structure and the chunks have a similar texture to ground beef. Textured soy protein contains about 70 percent protein.

Whey or Soy Protein Shakes; Photo courtesy of the U.S. Department of Agriculture, Source: Wikimedia Commons

Side Effects of Whey and Soy Protein

There are few significant side effects of using whey protein supplements. High doses can cause thirst, bloating, fatigue, increase in bowel movements, cramps, nausea, headache and reduced appetite. Because whey comes from milk, people allergic to cow’s milk should avoid whey protein; people who are lactose intolerant may tolerate whey protein isolates or hydrolyzed protein since they do not contain lactose.[1]

Other possible side effects include decreasing optimum kidney function, liver damage, and development of osteoporosis. However, none of these have been scientifically proven. Experts theorize excess amounts of protein put strain on the liver and the high levels of protein leads to the imbalance of minerals in the bones which causes loss of bone density. These medical experts stipulate the side effects would take large amounts of protein ingested over many years to reach the point of harm.

As far as soy protein is concerned, scientific research is not focused on the soy as a whole, but on its components. Isoflavones, daidzein, and genistein are components in soy available in over-the-counter powders and pills. Isoflavones are a weak form of estrogen and could adversely affect the body.[2]

Roux en y gastric bypass surgery is beneficial for many people who struggle to lose weight. Maintaining a healthy body is crucial post-surgery and eating enough protein is the main ingredient in aftercare. Using whey or soy protein as part of the daily required intake can help the patient stay on track.


The copyright of the article Using Whey and Soy Protein for Roux en Y Gastric Bypass Surgery Aftercare is owned by Cheryl Weldon and permission to republish in print or online must be granted by the author in writing



Oct 10, 2010 10:19pm
That was a great read! Thank you for sharing that. I rated it up and started to follow you, hope to see you in my list of friends too!

Apr 1, 2013 11:26pm
thanks for your kind words, I did friend you when you originally did a request. I hope you enjoy further article.
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  1. "WHEY PROTEIN." WebMD. 10/10/2010 <Web >
  2. "What is soy protein?." Soya. 10/10/2010 <Web >
  3. South San Francisco Medical Center Bariatric Surgery Department Patient Information Book. San Francisco: Kaiser Permanente, 2005.

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