Artificial sweeteners induce glucose intolerance by altering the gut microbiota, Suez et al 2014

1. Artificial sweeteners affect the gut microbiome in mice.
2. The affected gut microbiome increases obesity, diabetes, and other detrimental health measures.

Possible bad actors:

1. Aspartame
2. Saccharin
3. Acesulfame Potassium
4. Neotame
5. Sucralose

Other studies show that those who drink zero-calorie drinks end up consuming more calories than those that drink water. Zero calorie drinks seem to raise the hunger level.

Do Artificial Sweeteners Spike Your Blood Sugar? Helen West RD, Healthline.com 2017

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Stevia appears to not have the insulin response, and even reduces it:
https://examine.com/supplements/stevia

The best form of stevia are fresh leaves, or “green leaf stevia”, which is made of dried leaves ground up into powder form.

A convenient form is liquid drops where four drops equals the sweetness of a teaspoon of sugar. I haven't found drops without preservatives, but the amount of preservatives that 4 drops could contain is probably minimal.

Tevias brand stevia drops ingredients

STEVIA: Everything you need to know about how to harvest, dry, and store it! Everything Homemade on YouTube

I particularly like Instant Toasted Barley sweetened with stevia.

Another way to have your cake and eat it too. While not a zero calorie sweetener, you can definitely use it in place of sugar during your eating hours (in regards to intermittent fasting). The health profile looks good:
https://www.healthline.com/nutrition/erythritol

There are some ice cream brands using erythritol and stevia, such as “Halo Top”, but you could probably make your own ultimate low carb ice cream, with many keto recipes existing on the web.

I stop eating early in the evening as part of intermittent fasting, and when hungry at night, tea or lemon/lime water helps ease the hunger more so than water. However, you have to be careful which tea you choose.

The following tea was a gift. I would never get something that lists “natural spice and vanilla flavors with other natural flavors” as part of the ingredients. That's too deceptive. Also, I don't know how they get away with saying it's zero calories.

Celestial Seasonings Bengal Spice Tea ingredients: Cinnamon, roasted chicory, roasted carob, natural spice and vanilla flavors with other natural flavors, ginger, cardamom, black pepper, cloves and nutmeg.

Roasted carob and roasted chicory: https://www.myfitnesspal.com/food/calories/chicory-world-pure-roasted-chicory-462633872 https://www.myfitnesspal.com/food/calories/powdered-medium-roasted-carob-ceratonia-siliqua-424733838

Maybe it's good because it makes me drink tons of water, but maybe not good because sugary drinks lead to cavities. I estimate about 10 grams of sugar, or 30 calories per tea bag. It's low calorie, but it isn't zero calorie.