I've had trouble finding the right stuff. I first tried Stevia in liquid form from a trusted company called 'NOW'. It had no sweetness at all. In fact, it was unusable. I tasted a drop of it and the after-taste lasted for hours. Then I read that it is best used as a powder, so I tried a few different sample packs and was convinced that the claim of being 300x sweeter than sugar was flat-out untrue. The bitterness over-took any of the sweetness very quickly. Then I tried "Stevia in the Raw'. It was sweet, but use of it as a sugar substitute calls for a 3-1 ratio (Sugar to Stevia), still a far cry from the claims. This one was noticeably sweet, however. I used it in the 40-second chocolate muffin recipe that I posted yesterday (2 parts sugar/one part Stevia). If you're looking for that kick, it'll fall short and I'd recommend upping the sweeteners, or perhaps, adding some chocolate chips. However, that after-taste was still there, so I'd go with more sugar, not more Stevia.
For anyone looking at an alternative to carb based sweeteners, Stevia is ideal: Zero carbs, zero gluten, zero calories and a Glycemic Index of zero. Here's what this means: The gold standard for the Glycemic Index is Glucose, which has a GI of 100 and is the substance that all other foods are measured against. The higher the GI, the faster the food is absorbed and turned into glucose, which spikes the blood sugar. The higher the GI, the worse it is for your insulin receptors and usually leads to Diabetes, if abused, as the receptors shut down and won't allow insulin to escort the glucose into the cells. This is bad. The reason that Stevia has a Glycemic Index of zero, is that the the sweetening agents in Stevia (stevioside, steviolbioside, rebaudioside, rebiana, and dulcoside) are indigestible and pass through your system without being absorbed. There are, however, trace elements in Stevia that do get absorbed and are well-known for controlling blood sugar levels (chromium, magnesium, manganese, potassium, selenium, zinc and niacin).
In the end, it's a question of balance. Coffee and tea are good examples. It is easy to adjust to tea without any sweeteners. For me it's desirable. Coffee is a tougher proposition, especially if you are still using instant, or pre-ground coffee (Folgers, for example) because they need a lot of help to make them palatable. But, if you've learned the pleasure of grinding your own, you can learn to control the strength, or even find flavors that stand up well on their own...as in drinking it "black". Took a while, but I finally got there. When it comes to baked goods, the question of balance is even more delicate. Sugar adds more than sweetness, it creates texture and 'mouth feel', which Stevia does not do. And while sugar may trigger an appetite, when you consume Stevia you know that there will be that "chemical" after-taste waiting for you down the road. If you absolutely, positively should be avoiding carbs, then you either need to adjust to a blander choice of foods (which, ironically, will open up a whole new world of taste), or find ways to smother the after-taste of Stevia. I'll keep working with it. Like most other changes, it involves a process.