Jillian Michaels 30 day shred?!

So i started watching what i eat and hiking regularly and i went from 132 to 119 (sounds small but im 5'1") ive been doing the 30 day shred for almost a week now and ive been still watching what i eat and i should of been 118 today, ive been on a sch to lose a lb a week and i am on 1300 calories a day (more, if i exercise). I was 120, and i have noticed a difference in my body already as it is toner. So is this me building muscle or should i alter my diet somehow to lose more weight, or just stay the course? Share your experience or give me some advice please.