Replace a biscuit's sugar with artificial sweetener and a scientist must add ingredients to provide bulk and turn the biscuit's surface brown.

This is the popular line of reasoning for many diet soda drinkers. Unfortunately, current research indicates a possible link between artificial sweetener consumption and weight gain.

This means that it is neither sugar, nor a purely artificial sweetener, but is instead what Cargill calls a "natural" zero-calorie sweetener.