I think you are missing the point of Primal if you want to use those dressings. The splenda alone makes it a no go "by the rules". You can make your own lower fat dressings (use less oil). Or learn to eat and enjoy vegetables without salad dressings.
If you are doing primal and have cut the grains and excess sugars, you have more calories you can consume; so, you can have some full fat dressing on your salad since you aren't say, having a roll.
Use whatever you want, but if you don't up your fats, the Primal thing is probably not going to work for you. Primal also changes your palette. I have grown very sensitive to sugar tastes (ie, foods are too sweet) and it is what helps you develop new preferences for less processed foods. IE, for a snack, I'd rather have a banana than a snickers bar because I know the snickers bar won't taste good. If you keep eating artificially sweetened crap you will never lose this preference and will always want sweets.
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