Carbonated drinks, even diet versions, can have bad effects on your body. They provide calories, but have limited, if any, nutrients. Limit or avoid carbonated beverages from your diet to avoid any adverse effects. Replace them with water, 100 percent fruit juice or milk, all which provide some nutrients for your body. Carbonated drinks are full of calories. You may experience weight gain from drinking too many carbonated beverages. Full-calorie sodas can contain up to 110 calories. Having two cans a day provides over 200 calories. Based on an 1,800 calorie diet, this is around 12 percent of your total caloric intake for the day. According to the American Academy of Pediatric Dentistry, teenage girls who increase their consumption of carbonated drinks decrease their milk consumption by up to 40 percent. This can increase the risk of childhood obesity. If you count your calories, replace your full-calorie carbonated drink with a diet version. Diet sodas and carbonated juices have limited or zero calories, but are still devoid of nutrients. CO2 reacts with water to become carbonic acid (H2CO3). Some have argued that this excess acid in carbonation is dangerous. The stomach, however, is much more acidic (pH~1-2), and overwhelms the acidity of any carbonated drinks. To be concerned about ingesting acids that would make the stomach too acidic is misguided. It is a common misconception that digestive problems originate from too much acid in the stomach. Actually, antacids are oftentimes the opposite of what is healthy, since inadequate acidity can lead to insufficient digestion, which in turn leads to increased activity of intestinal bacteria, which causes increased bloating and reduced nutrient absorption. Furthermore testament to the safety of carbonic acid in the body is that it exists in the blood as a natural step toward the expiration of CO2. The blood level of carbonic acid (of metabolic origin, not ingested) is tightly regulated by the body. Therefore, the introduction of carbonic acid by ingesting carbonated water is not likely to cause harm to the blood system.