Addiction to any thing is too bad, even if it is to sodas. They have so many adverse effects on health like:

Weight Gain & Obesity: Drinking a single 330 ml can a day of sugary drinks translates to more than 1 pound (0.45 kg) of weight gain every month. The relationship between soft drink consumption and body weight is so strong that researchers calculate that for each additional sugar-sweetened soft drink consumed, the risk of obesity increases 1.6 times. According to researchers, the likely reason for weight gain in people who consume calories in sugar-sweetened beverages is failing to adequately reduce their intake of calories from other sources.

Sodas affect Kidneys: A three year study of over 1,000 men with a history of kidney stones showed that there was a clear-cut difference in the group's experiences, with much less renal colic in the men who had avoided soft drinks. Soft drinks acidified with phosphoric acid were the worst offenders. Colas of all kinds, of course, are well known for their high phosphoric acid content.


Harmful Effects of Soft Drinks (Soda)