I am wondering about this because I drank a diet coke the other day, it had no fat, no sugar, no calories... Is it actually healthy to drink?


Short: NO. It's not healthy neither for you nor for your environment. E.g. there is study (Jotham Suez et al., 2014), which indicates that there are problems with sugar substitutes when it comes to glucose metabolism. E.g. Acesulfame which comes often together with Aspartame is difficult to treat in wastewater. Just drink tap water or maybe mineral water.

  • That study was done with mice. While not making it void, it's a bit of a stretch to USE UPPER CASE and clearly state that artificial sweeteners are not healthy for a human being, since the evidence clearly does not support that as anything more than a speculation.
    – Eric
    Sep 8 '15 at 6:49
  • You may take another look at the study: "[...] To compare relative species abundance, we mapped sequencing reads to the human microbiome project reference genome database [...]". The study indicates, that artifical sweeteners have a negative effect on human glucose metabolism. Because there is no need to use artifical sweeteners and they have no explicit positive effect on human health, I conclude: They are not explicitly healthy, they are (in moderate dosages) not deadly and they may induce health issues, which is supported by scientific studies like the mentioned one.
    – Heywood Floyd
    Sep 8 '15 at 7:26
  • 3
    While there are well founded objections to the strength of conclusions of this study, the scientific community does agree that the results are interesting and deserve further follow-up research. Rome wasn't built in a day, nor was any important scientific concept proven in a single study. While one diet coke isn't likely to cause a lethal outcome, this study is a good find and keeping an eye on future studies is a good idea, IMO.
    – Lucky
    Sep 18 '15 at 13:30