While the debate raged about artificial sweeteners, I always took comfort from the knowledge that the sweetener I used, in coffee and iced tea, was not artificial; it was a pure natural extract from the leaf of a South American plant, Stevia rebaudiana. I'm not talking about a combination product like Truvia, packaged with a sugar alcohol, or Stevia in the Raw, combined with dextrose or maltodextrin (both 100% glucose chains) as "bulking agents." I am talking about 100% refined stevia leaf extract, either in powder or liquid form.
I use stevia powder in my coffee in the morning. I started out with a 16oz cup, with 12oz of coffee, about 2oz of heavy whipping cream (HWC) and a rounded 1g measure of stevia powder. When I decided that was too much fat from the cream, I downsized to a 12oz cup with about 1 1/2oz of HWC and a level 1g measure of stevia. When I discovered that I needed less than a cup to take my pills, I started experimenting with half a cup of coffee (and less HWC and stevia). That worked too, but I like my cup of coffee in the morning...
I also use stevia in liquid form in the cold-brew Lipton iced tea I make in half-gallon glass bottles for my go-to beverage during the day. It's quite refreshing when it's been chilled overnight in the refrigerator. I have 2 bottles and rotate them so one is always cold. After the tea "brews," I squirt in a couple eye droppers of liquid stevia and mix. I drink at least a half-gallon a day year-round -- more in summer -- to remain hydrated.
Because I generally eat Very Low Carb (LCHF) or "Keto," I am usually "keto-adapted." When the food I eat has been digested and absorbed, my body transitions without hunger from a fed to a fasted state. My metabolism changes from relying on the food I ate to the food it has stored on my body without slowing down. That's the theory of being "keto-adapted." And since I lose weight easily without hunger and with lots of energy when I follow this Way of Eating, I haven't felt the need to change my "stevia habit."
Doesn’t the stevia I take in my morning coffee raise my blood insulin? It surely must, to some extent. It is sweet! And although I probably lost my " first-phase insulin release" decades ago, nevertheless, the Cephalic Phase of digestion is still there, isn't it? Or, is the secretory response of insulin inhibited by not being hungry?
Likewise, if every glass of my sweetened iced tea is laced with stevia, won't it also put the brakes on my keto-adapted metabolism? Again, it doesn't seem to. Perhaps my description of my metabolic state as being “keto-adapted” -- which is entirely subjective; I do not have a keto meter or use keto test strips to test my urine-- is untrue. Perhaps I am not in a state of “nutritional ketosis” after all. Maybe I am just able to use body fat for fuel because I eat Very Low Carb, and therefore always have a low serum insulin, and therefore can always burn either the food I eat (almost all protein and fat) or the food stored around my waist (all fat).
But, again, if my body senses the "sweet" tea and coffee, won't that stop the breakdown of my body fat for fuel? And if that happens, and I have offered the body no carbs for a quick energy pick-me-up -- and only tricked it into thinking it would receive some glucose energy by the "sweet" signaling -- won't that slow my metabolism? It's supposed to, but again it doesn't. My body is pumped -- all day long -- on an empty stomach. Answer? "When appetite is depressed, this part of the cephalic reflex is inhibited," per this link in Wikipedia.So, after I take a few hours of exercise (garden work), I drink a glass of cold, stevia-sweetened iced tea, in summer with a few dill pickle spears for electrolyte balance. I know that by eating Very Low Carb (LCHF) I maintain a very low level of circulating insulin, and I am, therefore, never hungry. My body knows that it can always access my stored body fat to get all the energy it needs. Thus, it maintains energy balance (homeostasis) and a stable blood glucose without slowing my metabolism. Or so it seems to me.