Does "dirty" fasting affect results?

Fasting is significantly harder for me when I don't allow myself things such as flavored/sparkling water, zero soda, and zero sugar energy drinks. My main purpose for fasting is a tool for weight loss. So, my question is, how much does it really change? Would my body burn fat slower if I allow myself these things during my fast? I want to lose weight as fast as I healthily can, but I'm debating on cutting these things because I don't want them to affect my progress.