National Academy of Sports Medicine (NASM) Group Fitness Instructor Practice Exam

What is a true statement regarding incomplete proteins?

1. They provide all essential amino acids.

2. One can consume adequate protein by combining various protein-rich foods.

3. They are only found in animal products.

4. They should be avoided in a balanced diet.

The correct answer is: One can consume adequate protein by combining various protein-rich foods.

Incomplete proteins are those that do not contain all nine essential amino acids that the body cannot synthesize on its own. While they do provide some amino acids, they lack one or more of the essential ones, which distinguishes them from complete proteins, typically found in animal sources. The correct answer highlights that by combining different protein-rich foods, individuals can consume adequate protein. This approach is particularly important in vegetarian or vegan diets, where one might rely predominantly on plant-based protein sources that are often incomplete. For example, combining beans and rice ensures that all essential amino acids are provided, complementing each food's amino acid profile. The other statements do not accurately represent the nature of incomplete proteins. Incomplete proteins indeed do not provide all essential amino acids (making the first statement incorrect). Additionally, they are not exclusive to animal products, as many plants also contain incomplete proteins. Lastly, while it’s important to include sources of complete proteins in a balanced diet, avoiding incomplete proteins altogether would not be necessary or beneficial, as they can be part of a healthy diet when consumed in combination with other food sources.