You know what your carb tolerance is and if you can fit 4 per teaspoon into your diet, go for it.
But (there's always that "but"...)
Stevia is probably safe, but no one knows for sure right now, and refined sugar is still refined sugar with all of its other problems aside from carb content. You could buy your own bag of stevia and mix it with something to improve the taste. Even Splenda. Or a little maple syrup (probably very little).
Splenda's primary problem seems to be killing off some good gut bacteria, which could be a problem, but I'm not sure this is a reason to eliminate it-- maybe just reduce consumption. Another sweetener that got a bad name a while back is saccharine. Turns out that if you don't eat a pound or so a day it's not a carcinogen after all and if you can take the taste, it's cheap and OK.
I refuse, as much as possible, to consume aspartame (Equal) or sugar alcohols (all that stuff like erythritol that ends in "-ol"
. Aspartame just freaks me out because it's so common but so little is actually known about it and sugar alcohols often trigger diarrhea. Aspartame might cause some temporary nerve problems, and I guarantee you that getting the runs is not a preferred method of dieting.
Some might consider the Mayo Clinic a bit too conservative and establishment for their tastes, but here's their introduction to sweeteners:
http://www.mayoclinic.org/healthy-living/nutrition-and-healthy-eating/in-depth/artificial-sweeteners/art-20046936?pg=1