Swapping a regular Coca-Cola for Coke Zero or Diet Coke seems like a decent step towards drinking less sugar and calories, but these two "healthier" sodas each have their own ups and downs. There are three main differences between Diet Coke and Coke Zero: flavor, caffeine content, and type of sugar replacements used in the formulas.

Neither Diet Coke or Coke Zero contain sugar or calories, but each drink has its own unique taste. Coke Zero is near-identical to the original Coca-Cola because they share the same flavor base; meanwhile, Diet Coke uses different flavors that makes some drinkers prefer it over original Coke, regardless of nutritional content.

Additionally, Diet Coke contains 46 mg of caffeine per 12-ounce can, while Coke Zero contains less with 34 mg per 12-ounce can. Diet Coke is also sweetened with the artificial sweetener aspartame, while Coke Zero is sweetened with both aspartame and acesulfame potassium, the latter of which can mask bitter flavors in beverages.

MedicineNet concludes that neither Coke Zero or Diet Coke is a better pick than the other health-wise. Ultimately, the choice comes down to personal preference, but if you have a health condition such as diabetes, you may want to do further research on which artificially sweetened, sugar-free foods and beverages are right for you.