Is Your Protein High Quality?

Maintaining good protein status after bariatric surgery is a must!  With limitations in the size of the pouch coupled with the need for getting in enough fluids throughout the day this can be a challenge, especially in the early post-op phases.  Protein is important for everyone and by now you have probably heard that it is especially important for those undergoing bariatric surgery.  It aids in healing the incisions and the new stomach pouch.  It also helps to keep muscle mass during weight loss.  The goal is to lose stored fat, not muscle.

Did you know that not all protein sources are created equal?  Some protein foods are considered “complete proteins” while other protein foods are “incomplete.”  Complete protein foods are preferred as they contain all of the essential amino acids, which are the body’s building blocks.  The majority of complete protein foods come from animal sources (ie., meat, poultry, fish, eggs, and dairy) as well as a  as soy.  Incomplete protein foods lack one or more of the essential amino acids that the body needs to build muscles and repair tissues and cells.  Incomplete protein foods typically come from plant sources.  Examples of incomplete protein foods are beans, nuts, and peanut butter.  If you are following a vegetarian-style diet, incomplete protein foods can be combined to provide the essential amino acids your body needs.  It is important to check with your Registered Dietitian on how to combine plant protein foods appropriately if you are following a vegetarian diet.

One method that is used to evaluate the quality of a protein food or drink is called the Protein Digestibilty Amino Acid Score (PDCAAS).  This score is based on the amino acids in foods.  A score of 1.0 is the highest.  This means that the protein food has 100% of the amino acids in the right amounts needed by the body. PDCAAS can be helpful to make sure you are getting high quality sources at the beginning of your weight loss journey.  Use the chart below to see the PDCAAS ratings of common foods.

1.0 is the highest PDCAAS score, 0 is the lowest.


Serving size

Grams Protein



Chicken breast, boneless, cooked 3 oz. (85 g) 27 128 .91
Ground Beef, lean, cooked (15% fat) 3 oz  (85 g) 24 197 .91
Tuna, canned in water 3 oz (85 g) 23 99 0.90
Egg, hardboiled 1 large 6 78 0.97
Milk (1%) 1 cup/8 oz (244 g) 8 102 0.94
Yogurt, low-fat, plain 1 cup/8 oz (227 g) 12 143 0.95
Tofu 3 oz (85 g) 13.5 123 0.93
Salmon, baked 3 oz (85 g) 18.8 175 1.0
Rice 1 cup (158 g) 4.3 205 0.47
Peanut butter, chunky, unsweetened 2 Tbsp (32 g) 7.7 188 0.52
Corn (cooked kernels) ½ cup (82 g) 2.6 72 0.42
Peas (cooked) ½ cup (82 g) 4.1 62 0.73
Oatmeal, cooked 1 cup (234 g) 13 129 0.57
Whey Protein (isolate) 1 oz (28 g) 24 100 1.0
Whey Protein (concentrate) 1 oz (28 g) 22 113 1.0
Soy Protein 1 oz (28 g) 23 100 0.96


1.Health Canada, Nutrient Value of Some Common Foods (1999)

2.Tufts University School of Medicine; Harvard University

3.USDA National Nutrient Data Bank

PDCAAS scoring is also used by many bariatric programs to determine the quality of various protein supplements.  The following chart shows the PDCAAS of some of the common protein supplements on the market.  It is best to check with your bariatric dietitian or program to determine the protein supplement that is appropriate for you.

Product Name PDCAA Score Listed Protein Actual Protein
Chike 1.0 28 g 28 g
Bariatric Advantage High Protein Meal Replacements 0.96 27 g 26 g
Click Espresso 1.0 15 g 15 g
Dymatize All Natural Elite Whey Protein Isolate 1.0 24 g 24 g
Dymatize Elite Gourmet 1.0 21 g 21 g
EAS 100% Whey Protein 1.0 23 g 23 g
Genisoy Unflavored 1.0 14 g 14 g
ISS Complete Whey Powder 1.0 18 g 18 g
Labrada Lean Body for Her 0.93 49 g 46 g
Labrada Lean Body 1.0 40 g 40 g
Maximum Protein – Delicious Chocolate 0.93 22 g 21 g
MetRx 100% Natural Whey 1.0 23 g 23 g
MetRx 100% Ultra Myosyn 1.0 22 g 22 g
MetRx Meal Replacement 1.0 38 g 38 g
Syntrax Nectar – All Flavors 0.8 23 g 18 g
Optimum Nutrition 100% Gold Standard Whey 1.0 24 g 24 g
ProLab Nutrition Pure Whey Concentrate Powder 0.7 22 g 15 g
Revival Soy – All Flavors 1.0 20 g 20 g
Unjury – Chocolate, Vanilla, Strawberry, Unflavored 1.0 20 g 20 g
Unjury – Chicken Soup 1.0 21 g 21 g
Smoothie King Gladiator – All Flavors 1.0 45 g 45 g
Syntrax Matrix – All Flavors 0.87 23 g 20 g

Source: Weight Management Dietetic Practice Group Bariatric Dietitian Listserv

By Nicole Chase, RD, LD

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