First of all, you can harm the baby's development by slowing it down and causing a lower birth weight. Second, you don't want to lose weight during any point in your pregnancy even if your weight isn't in the belly. Third, since you're in early pregnancy, you'll have an even greater chance of miscarriage than any other point in pregnancy. I'd recommend you use this product only after breastfeeding completely terminates (If breastfeeding is your personal choice)
Congratulations on your pregnancy!