> As far as I'm aware, your metabolism doesn't slow down until you're close to starvation (all reserves used) A bad night's sleep or a lack of sunlight will sl

> As far as I'm aware, your metabolism doesn't slow down until you're close to starvation (all reserves used) A bad night's sleep or a lack of sunlight will slow your metabolism down. It's quite variable. Under eating for just a couple days will tank it. Going low protein (under, say, 80 grams) is also sure to lower metabolism.