Artificial Sweetener. Terribly dangerous, causing sickness, brain tumors, allergic reactions, memory loss, weight gain, and more. Breaks down into, among other things, formic acid, which is what causes hangovers. Also causes carbohydrate cravings! There's actually a memo circulated by the US Air Force warning its pilots to never have anything with any amount of aspartame, or be GROUNDED FOR A YEAR!
Bob started drinking diet coke with aspartame, then started to gain weight.