Well - in theory it's due to the rapid gain you've made. (Length of cycle, dose? Please include). Also - keep in mind Test E and DBol retain A LOT of water - therefor post-cycle your body will lose that.

Also - it's not your metabolism that is speeding up - it's the rapid gain that your body isn't used to - also your natural test production is still recouping (I'm guessing your in PCT now?) so your 'new' gains need to catch up once that is fully back.