Histone modifications commonly integrate environmental stimuli to cellular metabolic outputs by affecting gene expression. Many modifications, including some histone acetylation marks, do not always correlate to transcription, thus pointing towards an alternative role of histone modifications as potential metabolic reservoirs. Using an approach that integrates mass spectrometry- based epi-proteomics and metabolomics with stable isotope tracer studies, we demonstrate that elevated lipids in histone acetyltransferase (HAT)-depleted hepatocytes result from carbon atoms flowing from the deacetylation of multi-acetylated histone H4 to fatty acids. Consistent with this, the enhanced lipid synthesis in HAT-depleted hepatocytes is dependent on the activity of histone deacetylases (HDACs) and acetyl-CoA synthetase ACSS2. Furthermore, we show that during diet-induced lipid synthesis there is a reduction of multi-acetylated histone H4 in hepatocytes and in mouse liver. In addition, overexpression of histone acetyltransferases can reverse diet-induced lipogenesis by blocking lipid droplet accumulation and maintaining the levels of multi-acetylated histone H4. This study unveils an additional link between epigenetics and metabolism whereby histone acetylation reservoirs may serve as a carbon source for lipid synthesis.