Derived from a dark-green shrub, stevia -- which isn't a sugar -- comes in a variety of forms, including liquid drops and concentrated powder. "Stevia's much sweeter than sugar, but it doesn't have the caloric load or increase blood-glucose levels, so it doesn't impact your insulin levels," says Gina Sunderland, a Winnipeg-based registered dietitian. Some farmers markets sell stevia plants; simply add leaves to a pitcher of lemonade or iced tea for a sweet touch, or dry the leaves, crumble and add to loose teas.