Body chills are a normal reaction to transforming at the cellular level. Especially as the body is metabolizing fat. Fat is an insulator. It is a positive effect if you are getting chills because that means you are losing fat. As your body is transforming and it gets used to your new lower level of fat the thermogenic side of your increase in lean muscle will stabilize your body temperature and you can expect that will be a 3 to 6 month process.