Disclosed is an isolated antigen binding protein that induces FGF21-mediated signaling, wherein the antigen binding protein comprises: (a) a light chain CDR1 comprising an amino acid sequence at least SEQ ID NO: 167 or a light chain CDR1 sequence that differs by no more than a total of three amino acid additions, substitutions, and/or deletions from SEQ ID NO: 167 (GGNNIGSQSVH)； (b) a light chain CDR2 comprising SEQ ID NO: 176 or a light chain CDR2 sequence that differs by no more than a total of three amino acid additions, substitutions, and/or deletions from SEQ ID NO: 176 (DDSDRPS)； (c) a light chain CDR3 comprising SEQ ID NO: 190 or a light chain CDR3 sequence that differs by no more than a total of three amino acid additions, substitutions, and/or deletions from SEQ ID NO: 190 (QVWDSSSDHVV)； (d) a heavy chain CDR1 comprising SEQ ID NO: 122 or a heavy chain CDR1 sequence that differs by no more than a total of three amino acid additions, substitutions, and/or deletions from SEQ ID NO: 122 (NARMGVS)； (e) a heavy chain CDR2 comprising SEQ ID NO: 133 or a heavy chain CDR2 sequence that differs by no more than a total of three amino acid additions, substitutions, and/or deletions from SEQ ID NO: 133 (HIFSNDEKSYSTSLKS)； and (f) a heavy chain CDR3 comprising SEQ ID NO: 148 or a heavy chain CDR3 sequence that differs by no more than a total of three amino acid additions, substitutions, and/or deletions from SEQ ID NO: 146 (ILLLGAYYYYGMDV).
