Which best describes AMPK's role in energy metabolism?

• A. AMPK inhibits glucose uptake and fatty acid oxidation
• B. AMPK stimulates fatty acid synthesis
• C. AMPK reduces mitochondrial biogenesis
• D. AMPK stimulates glucose uptake and fatty acid oxidation

Answer: (D)

AMPK acts as the cellular energy sensor, becoming activated when energy is low (high AMP/ADP relative to ATP). When active, it switches on pathways that generate ATP and upregulates processes that bring in or burn fuel. In muscle and other tissues, AMPK promotes glucose uptake by helping move GLUT4 transporters to the cell surface, increasing glucose entry during energy stress. It also drives fatty acid oxidation by inhibiting acetyl-CoA carboxylase, lowering malonyl-CoA, which relieves the brake on CPT1 and lets fatty acids enter mitochondria for oxidation. Over time, AMPK can boost mitochondrial biogenesis, increasing oxidative capacity. In contrast, inhibiting glucose uptake and fatty acid oxidation, stimulating fatty acid synthesis, or reducing mitochondrial biogenesis would oppose its role in meeting immediate energy needs. Therefore, the description that best fits AMPK’s role is that it stimulates glucose uptake and fatty acid oxidation.