"smiling woman holding a protein shake"Written By: Carley Salas MS, RDN, CDN

Protein is one of the most important nutrients of concern for bariatric surgery patients. Since bariatric surgery reduces the capacity of the stomach to a very small volume, high-protein foods should always be eaten FIRST or you may become too full to eat them. It should be included in all of your meals after surgery as protein provides many important benefits including:

  • Aids in proper wound healing after surgery
  • Helps keep your skin, hair, bones and nails healthy and strong
  • Helps form hormones, enzymes and immune system antibodies that help your body function effectively
  • Balancing the acid/base environment within our body
  • Helps your body burn fat instead of muscle for healthier weight loss
  • Supports an efficient metabolism
  • Helps curb hunger between meals

Liquid Protein Shakes Help You Meet Your Daily Requirements

It can be challenging to consume enough protein from foods alone during the first several months following surgery. Many patients continue to drink liquid protein supplements well past the initial full liquids stage to meet their daily protein requirements. Protein shakes are a nutrient dense, convenient, and inexpensive protein source. Keep in mind not all protein supplements are created equal, and there are certain parameters in place for the calories and macronutrients of a quality protein shake that is appropriate for after surgery. These details will be discussed during your one on one appointment with the bariatric dietitian.

Whey Protein Concentrate vs. Whey Protein Isolate

Protein shakes are typically made from whey protein isolate, or whey protein concentrate, and sometimes a combination of both. Whey protein isolate is the preferred form for post-op patients as it is a higher quality, complete protein that has been “isolated” from fat and lactose that is naturally found in milk so it has less calories coming from carbohydrates and fat, and most calories coming strictly from protein. Whey protein concentrate can contain varying amounts of carbohydrates and fat along with the protein. Because of this, whey protein isolate often has a slightly higher price point than whey protein concentrate. Another benefit to choosing whey protein isolate is that the lactose has been removed. If you have trouble digesting dairy, you will want to seek out a shake that is whey protein isolate to avoid any digestive discomfort. 

What About Plant Based Protein Shakes?

Keep in mind that plant-based or vegan protein shakes may not provide a “complete” protein source. A complete protein contains all 9 essential amino acids that make up a protein molecule required to build and repair muscle tissues in the body, and many plant sources of protein do not contain all 9 amino acids on their own. Amino acids are called essential because the human body does not make them and they must be consumed in the diet. If you follow a strict vegan diet, make sure to choose a protein shake that is made up of a blend of protein sources like pea protein and hemp protein together to ensure it’s a complete protein, or choose one that is soy based which is a complete protein.  Many plant-based protein shakes also contain lower amounts of protein than their whey based counterparts, so you may need to drink more of them to meet the recommended amount of daily protein to prevent muscle mass loss after surgery. 

Protein Powders vs. Premade Shakes

Both options are acceptable for bariatric surgery patients. Everyone’s palates are different, and some people prefer the taste of protein powders over premade shakes or vice versa. Protein powders tend to be more cost effective per serving because you are paying extra for the convenience and packaging involved in the ready-to-drink shakes. If you choose a protein powder, you also have more flexibility with adjusting the consistency to your preference depending on how much liquid and the type of liquid you mix it with. Good choices include fat free milk, unsweetened almond or soy milk, or plain water/ice. If you use a dairy milk or soy milk, you get the benefit of the additional grams of protein to help you meet your protein goals, as 8oz of milk usually has about 8 grams of protein. 

Is Collagen a Good Protein Source?

Collagen is the most abundant protein in the body, accounting for about 30% of the body’s protein1. It provides structure and flexibility to ligaments, tendons, muscles, and bones as well as the skins elasticity. It also makes up hair, veins, and nail structure. Collagen is naturally produced by the body, but its production begins to decline around the age of 30 and existing collagen breaks down at a faster rate1. This decrease in collagen over time is what causes wrinkles and weaker joints as we age.  Collagen peptide supplements have become very popular over the last 5+ years because of this. Many collagen supplements contain about 10-20 grams of protein per serving (depending on the brand) and come in a powder or capsule form. However, while it is a helpful supplement, collagen is only made up of about 7-8 different amino acids so it is not technically a complete protein.  Animal proteins are the only dietary source of collagen, so including meats, seafood, and dairy is a great way to increase your collagen intake through food. 

Overall when it comes to choosing a protein supplement, there are many factors to consider like cost, taste, convenience, and quality. Having a variety of protein supplements to choose from whether its different brands or different flavors can help prevent boredom or flavor fatigue as you will be drinking 2-3 protein shakes a day pre-op and post-operatively for a period of time before other foods are allowed. Keep in mind that your taste buds may change after surgery, and protein shakes you liked prior to surgery may not taste as good after surgery so having some alternatives as back up is important.   




Carley Salas MS, RDN, CDN
By Carley Salas MS, RDN, CDN
Bariatric Dietitian Educator

Carley Salas, MS, RDN, CDN is Garnet Health Medical Center’s Bariatric Dietitian Educator. She received her Bachelor’s and Master of Science Degrees in Nutrition and Dietetics from the State University of New York College at Oneonta. She is a Certified Dietitian-Nutritionist, holds an Academy of Nutrition and Dietetics Certificate of Training in Adult Weight Management, and is a member of the Academy of Nutrition and Dietetics (AND). Carley is passionate about nutrition and helping others reach their health and wellness goals through individualized counseling and nutrition education. Carley can be reached at (845) 333-2830 or

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