Probably nothing in the world arouses more false hopes than the first four hours of a diet.

The line is a dry, self-deprecating joke about the psychology of self-improvement. The “first four hours” of a diet are when motivation is highest and the costs feel abstract; early restraint can create an illusion of imminent transformation. By calling those hopes “false,” the speaker punctures the fantasy that change is quick or linear, implying that real progress depends on sustained habits rather than a brief burst of willpower. The humor works by contrasting the grand expectations people attach to dieting with the trivial amount of time that has actually passed, highlighting how easily optimism outruns evidence.