One of the biggest things with soda aside from the sugar (and not many know either) is that the carbonation effects your ATP production, which effects fat stores and I believe will even cause some water retention (ie bloating). So even diet soda is bad for more than the obvious reasons... Another key thing that many don't consider is you'll see pretty dramatic results (considering the effort involved) just from increasing water consumption. If you were to consume 1 oz of water per lb of body weight in a day for say, a week. It would essentially flush the excess sodium from your body and you wouldn't retain nearly as much water. It would make you appear like you've lost maybe 4-5 lbs just from dropping excess water and bloating.
I personally dropped 30 lbs in 3 months by cutting out soda completely. I worked out regularly and was still a flabby 195... cut out soda and 3 mo's later I'm a not-flabby 165, and a couple years later after watching my diet and trying to gain good weight and I'm a not-flabby 180... hoping for 190 by end of January![]()