Answer: Sugar-Free Jell-O is zero carbs but contains non-keto sweeteners.
At 0 g of carbs per serving, Sugar-Free Jell-O is a tempting, low carb treat. And it would be fine for keto were it not for its problematic sweeteners.
Every flavor of Sugar-Free Jell-O Gelatin contains maltodextrin, a notoriously un-keto sweetener. Maltodextrin has a glycemic index between 85-105, placing it on par with sugar for the effect it has on your blood sugar. This means that despite its zero carb label, it can still interfere with your ketosis. One study found that maltodextrin may interfere with gut health, making you more susceptible to disease.
That said, Jell-O labels don't disclose the exact quantity of maltodextrin the product contains. In small enough dosages, maltodextrin may not have an impact on ketosis. Many people eat sugar-free Jell-O while still achieving their keto goals.
If you absolutely love Jell-O, you can choose to integrate it into your way of eating, but approach it with caution. If not, there are plenty of sweets with a keto-friendly ingredient list, such as Lily's Chocolate Bars or SlimFast Keto Fat Bombs.