Certified Sports Nutritionist from the International Society of Sports Nutrition (CISSN) Practice Exam 2026 - Free Sports Nutritionist Practice Questions and Study Guide

Protein serves several critical roles in the body, and one of its primary functions is as a source of fuel. While carbohydrates and fats are typically the body's main energy sources, protein can also be utilized for energy, particularly during prolonged exercise or in conditions where carbohydrate intake is low.

When the body is in need of energy and other sources are unavailable, it can break down proteins into amino acids, and then these amino acids can be converted into glucose through a process called gluconeogenesis. This allows protein to play a vital role in maintaining energy balance and supporting various physiological functions.

Beyond energy provision, proteins are essential for growth, repair, and maintenance of tissues, making them invaluable for athletes and active individuals needing muscle recovery and support. They also contribute to the formation of enzymes, hormones, and other substances vital for health.

The other options do not accurately reflect the primary role of protein in the body. While fat transport is primarily performed by lipoproteins, nerve transmission mainly relies on neurotransmitters and does not involve proteins as a direct energy source. Energy storage mainly refers to glycogen in muscles and liver or triglycerides in adipocytes, rather than protein.