If you're thinking, "Wow, the benefits of HIIT sounds amazing and I need to start ASAP," but also wondering, "How long will it take to see results from HIIT?," there isn't an exact answer. "It comes down to the individual . . . you can lose one to two pounds of adipose tissue within a week," Rondel explained. If you're less conditioned, you may initially lose more than one pound a week.