AFAA Personal Trainer Certification Practice Exam 2026 - Free Personal Trainer Practice Questions and Study Guide

The correct answer is complete protein. Complete proteins are defined as those that contain all nine essential amino acids in sufficient quantities required by the body. Essential amino acids are those that the body cannot synthesize on its own, meaning it must obtain them through dietary sources.

Animal proteins, such as meat, dairy, and eggs, are typically classified as complete proteins because they provide all essential amino acids. There are also some plant-based sources, such as quinoa and soy, that are considered complete proteins as well. This characteristic is important in nutrition because consuming a balanced amount of complete proteins can support muscle repair, immune function, and overall health.

On the other hand, incomplete proteins do not contain all essential amino acids and are typically found in certain plant sources. Vegetable protein usually refers to protein derived from plants but does not necessarily imply that it includes all essential amino acids. Moderate protein does not refer to a specific type of protein regarding amino acid completeness, making complete protein the clear choice for providing all essential amino acids.