Synonyms for Fatten up:

• n.

  •
  • stay off,
  • slim down,
  • trim down,
  • put on,
  • sweat off,
  • lose.
  •fat (noun)
  • fat.
  •fatten (noun)
  • fatten.
  •fatten out (noun)
  • fatten out.
  •fatten up (noun)
  • flesh out,
  • plump out,
  • plump,
  • fill out.

• Other synonyms:

  •
  • fat camp,
  • waste away.
  •
  • work off.