Final answer:
Nutrient utilization is the catabolic pathway, involving the breakdown of larger molecules to release energy, while adipose tissue stores can change with diet, contrary to the statement provided.
Step-by-step explanation:
The metabolic pathway that is catabolic is nutrient utilization. Catabolic pathways involve the breakdown of larger molecules into smaller, usable forms, releasing energy in the process. This contrasts with anabolic pathways, which require energy to build larger molecules from smaller units. Examples of catabolic processes include the digestion of food into monomers and the breakdown of glucose via glycolysis. As for adipose tissue stores, the statement that they do not fluctuate significantly with diet is false. Adipose tissue stores can indeed change depending on diet and energy expenditure.