A friend mentioned a drink called “kumis”, and on researching it, I thought it sounded like Calpis, aka Calpico in the English speaking countries.

The base of kumis sounded like buttermilk. I’d made a drink just like Calpico with buttermilk.

Turns out that buttermilk is 13g of carbs per cup. I have a recipe that uses around 1/4 cup of buttermilk to produce a tall glass of Calpis. This has only 4g of carbs.

1/4 cup buttermilk
1 – 2 packets sweetener
ice to fill glass
water to fill

That’s it. Just mix the buttermilk and sweetener together, add some water and keep stirring. Then, add ice and water, stirring.