The origin of the "biscuit" quote by Clark Kellogg was back during the training camp of the Chicago Bears' legendary Buddy Ryan defensive team. When Refrigerator Perry showed up to camp as a rookie, the rest of the D-line was all over him. Since that line was composed of Dan Hampton, Steve McMichael, and Richard Dent, they could say whatever they wanted to anyone.
Hampton looked at Perry and started calling him "Biscuit". The nickname stuck in the locker-room, though not in the media. The press asked Hampton why they were calling Perry "Biscuit", and Hampton said "because he's just one biscuit short of 400 pounds".
[I don't mind Clark Kellogg using a good story for a different game comment, and like CK quite a bit, although he too stole Greg Kelser's nickname of "Special K".]
p.s., I would have been stunned if Nix had shown up anywhere near 300-310. Nix is viewed as a freakish big man of the "alabama-style" monsters that have been appearing down there. He is viewed as carrying that weight just fine. He is supposed to be the Mountain-in-the-middle which cannot be moved, and who will move you. I'm sure that Terry's numbers are correct.