What’s the Difference Between Fire, Lean Fire, and Fat Fire? Written by Adam on May 14, 2018. Updated October 24, 2018. 9 min read. Data, Featured, Financial Independence. 18 CommentsPeople use the terms “fire”, “lean fire” and “fat fire” all the time – but what do they mean? In this data-driven post, we look into the numbers behind these pursuits and what you could do to hit your numbers.