Answer:
Malonyl-CoA, a key intermediate in fatty acid synthesis, inhibits carnitine acyltransferase I, thereby blocking the entry of fatty acyl units into the mitochondrion for oxidation.
Fatty acyl-CoAs, the substrates for fatty acid oxidation, inhibit fatty acid synthesis by interfering with the polymerization of acetyl-CoA.
Hormonal effects on adipocytes are opposed; insulin promotes fatty acid synthesis by several mechanisms; while glucagon promotes fat breakdown and fatty acid oxidation