The macromolecule that your body never breaks down for energy is nucleic acids. While the body breaks down carbohydrates, proteins, and fats to obtain energy, nucleic acids (DNA and RNA) are not catabolized for energy production. Instead, nucleic acids are broken down into their nucleotide components primarily for recycling and synthesis of new nucleotides, not for energy use

. To clarify:

• Carbohydrates are broken down into sugars like glucose, which is the primary and preferred energy source for most cells

• Proteins are broken down into amino acids, which can be used for energy but primarily serve as building blocks for new proteins

• Fats (lipids) are broken down into fatty acids and glycerol, which are a major long-term energy source

• Nucleic acids are broken down into nucleotides but are not used as a fuel source for energy production

Thus, nucleic acids are the macromolecules your body does not break down to produce energy.