Vega shakes are soy free, sugar free other than stevia and plant based in the protein source. The lowest carb I found during my investigation into finding a soy free low/lower carb shake. It's six grams carb net per 8 oz shake, IIRC. I only ever tried the chai tea flavor and the taste was...okay.

If a slightly slimy texture squiks you out (there are far worse shake offenders here, including the Atkins brand ones), it may not work. They do sell by singles, so you could try out before investing in a full-sized canister.

The only thing is if you are sensitive to, or develop a sensitivity to, the chlorella in it that's all she wrote as the such causes acute vomiting and diarrhea within a couple hours of ingestion.