A lost circulation material (LCM) composition for sealing a lost circulation zone in a wellbore is disclosed that includes from 50 weight percent to 97 weight percent epoxy resin and from 2 weight percent to 30 weight percent curing agent. The epoxy resin may include at least one of 2,3-epoxypropyl o-tolyl ether, alkyl glycidyl ethers having from 12 to 14 carbon atoms, bisphenol-A-epichlorohydrin epoxy resin, or a compound having formula (OC2H3)—CH2—O—R1—O—CH2—(C2H3O), where R1 is a linear or branched hydrocarbyl having from 4 to 24 carbon atoms. A method for isolating a lost circulation zone using the LCM compositions is also disclosed and includes introducing a spacer fluid to the lost circulation zone, introducing the LCM composition to the lost circulation zone, and curing the LCM composition in the lost circulation zone to isolate the lost circulation zone.