Diane Keaton went through a physical change in the weeks leading up to her death. The saddening news broke on Saturday that at 79, the Book Club star tragically passed away. Little is known, but an unnamed friend told People on Saturday her health "declined very suddenly, which was heartbreaking for everyone who loved her." The source called her death "unexpected," but told the outlet she spent her final months "surrounded only by her closest family, who chose to keep things very private." They added: "Even longtime friends weren't fully aware of what was happening.