The absorptive state of human metabolism. (A) In the absorptive state, food is digested and absorbed primarily as glucose and amino acids. The schematic shows influx of glucose into the blood and the modeling-defined fractions of intake into each of the three models. Essential amino acids and fatty acids were also provided. For the multi-tissue simulations, the AM model stores triacylglycerol, the MM stores protein and glycogen, and the HM stores glycogen. Some of the glucose delivered to the HM was converted to fatty acids that are transported to the AM for triacylglycerol production. (B) The flux spans for the three cell-specific reconstructions individually and when integrated are shown. Integration had a constraining effect on the HM and MM models, but had an opposite effect on the AM. This was due to fatty acid production by the HM that was then transported to the AM. GLC = glucose, GGN = glycogen, AA = amino acids, FAs = fatty acids.