That’s why it’s considered a low-calorie option — Diet Coke’s nutrition label claims the beverage contains zero calories ... There’s also caffeine to factor into the equation.
In a sense, caffeine is the drug that made the modern world possible. And the more modern our world gets, the more we seem to need it. Without that useful jolt of coffee—or Diet Coke or Red Bull ...
When it came to the actual liquid, they wanted their cola to taste different to Coke and Pepsi, so they used less sugar, and added lemon juice. They also decided to add a lot more caffeine.