Lean

The word "lean" as a descriptor for a manufacturing system was coined in 1988 by John Krafcik, an MIT researcher studying global automobile production.1 Krafcik was comparing the Toyota Production System with Western mass production methods and needed a term that captured Toyota's approach of using less of everything: fewer workers, less factory space, smaller inventories, and shorter development times.

The term gained global reach through the 1990 book The Machine That Changed the World by James Womack, Daniel Jones, and Daniel Roos, which presented the findings of MIT's International Motor Vehicle Program.2 The book documented how Toyota's system outperformed Western manufacturers on nearly every metric while using roughly half the human effort, half the manufacturing space, and half the investment in tools.

Toyota's own terminology was different. Taiichi Ohno, the engineer who built the production system at Toyota starting in the 1950s, described his approach as the elimination of muda (waste), muri (overburden), and mura (unevenness).3

By the 2000s, "lean" had expanded far beyond manufacturing. Lean principles were applied to hospitals, software development, government agencies, and startups. Eric Ries published The Lean Startup in 2011, applying the concept of eliminating waste to entrepreneurship.4

The English word "lean," in its original sense of thin or having little fat, traces to the Old English hlæne. Krafcik chose the word deliberately, contrasting it with the "buffered" systems of Western mass production, which maintained large inventories and extra workers as cushions against disruption.1