I found something odd in a book my mom bought me years ago... it was called "Digimon Power", and while the book itself is focused on Digimon in general, it also has references to other games and/or manga. Here's the little tidbit I found in page 187: "Care and Training"

"-- also, taffy and candy can shorten a monster's life."

Candy could, perhaps, shorten lifespan because as some on this site have stated that bad weight control could shorten a monster's lifespan. HOWEVER, taffy is considered different subject. It works like Nuts Oil in MR2, and based on the charts I found...:
"Taffy: Fatigue -50, Spoil +2 and Form +5"

The form gain is almost irrelevant unless you indulge your monster over, oh, I dunno, 16 pieces of taffy, which is just sick because I wouldn't waste that much money if I could just feed my monster 4 pieces of candy (which I wouldn't bother to do anyway). Form can be shaved off with Powder or any vigorous activity in general.

If I might say so myself, if it's not a hoax, then it's a mere exaggeration, but I ought to post it here anyway for those poor people who wasted a bit of their time having to rest their monster instead of popping 1 or 2 Taffies in.

Wow thanks!