 Thermodynamics-Based Metabolic Flux Analysis (TMFA) is a specialized type of metabolic flux analysis which utilizes linear thermodynamic constraints in addition to mass balance constraints to generate thermodynamically feasible fluxes and metabolite activity profiles.TMFA takes into consideration only pathways and fluxes that are feasible by using the Gibbs free energy change of the reactions and activities of the metabolites that are part of the model.See Isotopic labeling for a brief treatment of stable isotope labeling.