I've been doing HIIT for a few weeks and like it.. However, it really fucks the rest of my day up. I feel at least 25% more tired than normal [obviously].. but - what can i do to counter this? I don't want to eat more as I am trying to cut down, but its effecting my work as I am just more lazy etc.. Thanks for any help edit: I've been doing HIIT for 25 minutes [well 20 min really because i do a 5 minute warmup jog], AFTER medium-heavy intensity lifting. I know a lot of people say to do HIIT on different days, and maybe this is why im so burnt out?