Metabolomic profiling consistently identifies elevated levels of ketone bodies (β-hydroxybutyrate, acetoacetate), branched-chain amino acids (leucine, isoleucine, valine), and trimethylamine-N-oxide (TMAO) in individuals consuming habitual meat-rich diets, serving as biochemical signatures of enhanced fat oxidation, protein catabolism, and gut microbial metabolism of animal-derived nutrients.

When a person eats a lot of meat and very little carbohydrate, the body switches to burning fat for energy, making ketone bodies as fuel. At the same time, the body breaks down meat proteins into amino acids, which are converted into glucose to keep blood sugar stable. The gut bacteria that live in the intestines feed on parts of meat that aren't digested, producing a compound that the liver turns into TMAO. These three processes happen together and create the same chemical signature found in the blood of people who eat meat-heavy diets.