Stevia extract or powder: Sweetener for all occasions: this is a delicious non caloric sweetener which is a natural product from the Sweetleaf plant(s). Many companies make powders and extracts. An example below shows the variety of available products. 3 drops in a glass of water gives you a delicious flavored drink in seconds.

For us milk drinkers there are a couple of no carbohydrate options:
Coconut milk has 45 Kcal all from a “good” saturated fat.
Almond milk contains 30 Kcal all from protein.