Glen "Big Baby" Davis' pursuit of his dream body in prison might be a little tougher than he imagined ... 'cause TMZ Sports has obtained the menus from his first couple weeks in the slammer -- and they featured a whole lot of carbs.
Davis entered into FPC Duluth in Minnesota back in October ... after he was sentenced to 40 months behind bars for his role in a scheme that defrauded the NBA's Players' Health and Benefit Welfare Plan.