Why Do I Feel Nauseous After Eating Lots of Protein?

Whether you consume too much protein because of an extra-large meal, an excess volume of a protein-dense supplement or a protein-rich food to which you have an adverse reaction, excess protein intake can make you feel nauseated. The cause of your digestive distress depends on the circumstance of your protein consumption, and prevention of future problems depends on why the excess protein made you feel sick. Consult a dietitian or your health care provider if you suspect a link between protein and nausea or other digestive issues.

Specific food proteins can cause your immune system to mount an inflammatory response to what it perceives as a foreign substance in your digestive tract. For example, if you are allergic to the protein in wheat, consuming too much of it can cause a variety of allergic symptoms, including nausea. If you are severely allergic, even a small intake of the protein can trigger histamine responses such as digestive problems, hives and even swollen airways or other even life-threatening reactions. In adults, most food allergies are caused by proteins in shellfish, fish, peanuts or tree nuts. Children also may be allergic to eggs, cow's milk, wheat or soy, although some children eventually outgrow their food allergies.

Food intolerance is a digestive disorder rather than an immune disorder with an associated inflammatory response. In food intolerance, you lack a specific component of your digestive system that allows you to fully digest a certain food. For example, in lactose intolerance, your body does not synthesize sufficient lactase to digest the milk sugar lactose. Therefore, the undigested lactose moving through your intestinal tract can cause digestive distress with symptoms such as nausea. Even though the food you are intolerant of might not be a protein, it might be another food component associated with a food protein, such as lactose with milk. Food intolerance can take longer to identify than food allergies because the symptoms — such as migraines, cough or stomachaches — can be difficult to associate with a particular food.

Simply eating too much of a protein-rich food can make you nauseated due to indigestion. When you consume protein, digestive enzymes in your stomach and small intestine break down the large protein molecules into individual amino acids that you can then absorb. Too much protein, however, can overwhelm the ability of your digestive enzymes to match the pace with which you take in these food proteins. Until your digestive system catches up, you may experience nausea and other symptoms of digestive upset.

In the case of a food allergy, avoiding the offending protein eliminates the likelihood of feeling nauseous. For food intolerance, you may not necessarily need to avoid the protein associated with the food component you cannot tolerate. If you want to continue to consume that protein, you may need to eliminate the intolerable component from the protein. For example, drinking lactose-reduced milk allows you to consume milk protein while avoiding lactose. If you feel nauseous because you ate too much or too fast, moderating your protein intake can help you avoid feeling sick in the future.