That all depends on what kind you were drinking, how much per time and how many per day...

you have to figure it out - cutting out 3,600 calories is equal to 1 pound. to lose 30 pounds you would have had to cut out 108,000 calories in pop. If you only used to drink one 8 oz. coke per day then it's not possible for it to be from that - if however you drank only one of 7-11's "big gulp" per day or 4 or 5 cans of pop per day, then it's not only possible, then that is exactly what dropped the weight. But to take it further, if you were drinking LESS than that, maybe because you are not drinking the pop you are not eating some OTHER things that go good with that thus cutting out a lot MORE calories. (let's say you love to drink a coke with pizza and now instead of eating 4 slices of pizza you are only eating 2 due to that) - I hope I explained this right! My daughter gave up Coke for Lent one year and dropped about 15 pounds - Lent is only 40 days, so VERY possible for you to lose 30 in 120 days!