ISSA Nutritionist Practice Exam 2025 – Comprehensive All-In-One Guide to Exam Mastery!

The process of converting ingested nutrients into energy within the body is referred to as metabolism. This term encompasses the biochemical processes that occur in living organisms to maintain life, which includes both the breakdown of nutrients to produce energy (catabolism) and the synthesis of necessary compounds (anabolism).

During metabolism, carbohydrates, fats, and proteins from food are transformed through various biochemical pathways into adenosine triphosphate (ATP), which is the primary energy currency of the cell. This conversion is essential for fueling cellular functions, movement, growth, and repair.

Respiration, while related to energy production, primarily pertains to the cellular process of using oxygen to convert biochemical energy from nutrients into ATP, and it is often considered a component of metabolism. Digestion refers to the mechanical and chemical processes that break down food into smaller molecules that can be absorbed and utilized by the body, but it is distinct from the metabolic conversion of those nutrients into energy. Fermentation is a specific metabolic process that occurs in the absence of oxygen, resulting in the production of energy from glucose, typically yielding byproducts such as alcohol or lactic acid, and isn't the general term for the broad process of energy conversion.