Soda has an extremely high amount of sugar. Once that much of the sweet stuff gets into the body, the pancreas begins working. It quickly produces insulin to handle the sudden high sugar intake, wreaking havoc on your blood. Your body cells have been alerted to absorb blood sugar for energy or storage in the form of fat. Big swings in your blood sugar levels can make you feel exhausted and increase the risk of type 2 diabetes and heart disease.