Justin Bieber beefs up - but only for Christmas

Justin Bieber has confessed he packs on the pounds over Christmas. The 17-year-old singer admitted a 20lb weight gain is not unusual thanks to her grandmother's home cooking. "I usually gain like 20lb around the holidays eating my grandma's food," he told Us Weekly. "She makes amazing turkey, great stuffing, everything. And peach cobbler!" The season will also see the release of the Bieb's first Christmas album. "There are a couple of original songs," he revealed. "There are some classics, but mostly originals."