NOTE: I had originally included Stevia along with artificial sweeteners in raising insulin levels without the corresponding rise in glucose levels, based on the claims of the author I’ve quoted below.

However, upon readers questioning this, I actually located the study the author cites in his book, as well as another article citing the same study, and believe the author has incorrectly interpreted the results. Both the study and the interpretive article state that Stevia did NOT elevate blood insulin levels the way aspartame and sucrose did.

Study: “Post-hoc comparisons revealed that postprandial insulin levels were significantly lower in the stevia condition compared to both the aspartame (p = .04) and sucrose conditions…”

Article citing study: “ interesting study explored the effects of various sweeteners on altering the insulin release from a meal (i.e., drinking a sweetened drink while eating). Drinking sucrose (sugar) with the meal had the highest effect, but, interestingly, aspartame consumption with the meal was almost identical to sugar. Stevia, however, had no effect.”

So, I’ve removed my own similar references to Stevia from this article, and just kept those that are included in the excerpts from the author’s book, and highlighted them in yellow in order to call them out.

In my past few years of nutritional studies and resultant weight loss and much improved body composition (particularly for my age), I’ve come to understand the concept of keeping your blood glucose low, and thus avoiding the correlated insulin spike, in order to lose weight—and also to help remediate insulin resistance (a form of type 2 diabetes).

So, I get it.

But all this time, I was not aware that artificial sweeteners—though they have little impact on blood glucose—actually do raise insulin levels, nearly as much as table sugar!

I discovered this today while reading The Obesity Code: Unlocking The Secrets Of Weight Loss by Jason Fung, M.D.

Published recently (2016), Fung’s book “zeroes in on why insulin resistance has become so prevalent”, and explains how “weight gain and obesity are driven by hormones—in everyone—and only by understanding the effects of insulin and insulin resistance can we achieve lasting weight loss.”

Here’s the shocking information I just read about artificial sweeteners:

“Presuming that artificial low calorie sweeteners are beneficial results in an immediate and obvious problem. Per capita consumption of diet foods has skyrocketed in recent decades. If diet drinks substantially reduce obesity or diabetes, why did these two epidemics continue unabated? The only logical conclusion is that diet drinks don’t really help.

There are substantial epidemiologic studies to back that up. The American Cancer Society conducted a survey of 78,694 women, hoping to find that artificial sweeteners had a beneficial effect on weight. Instead, the survey showed exactly the opposite. After adjustment for initial weight, over a one-year period, those using artificial sweeteners were significantly more likely to gain weight, although the weight gain itself was relatively modest (less than 2 pounds).

Dr. Sharon Fowler from the University of Texas Health Sciences Center at San Antonio, in the 2008 San Antonio Heart Study prospectively studied 5,158 adults over eight years. She found that instead of reducing the obesity, diet beverages substantially increased the risk of it by a mind-bending 47%. She writes, “These findings raise the question whether [artificial sweetener] use might be fueling—rather than fighting—our escalating obesity epidemic “

The bad news for diet soda kept rolling in. Over the 10 years of the Northern Manhattan Study, Dr. Hannah Gardner from the University of Miami found in 2012 that drinking diet soda was associated with a 43% increase in risk of vascular events (strokes and heart attacks). The 2008 Atherosclerosis Risk in Communities Study (ARIC) found a 34% increased incidence of metabolic syndrome in diet soda users, which is consistent with data from the 2007 Framingham Heart Study, which showed a 50% higher increase of metabolic syndrome. In 2014, Dr. Ankle Vaasa from the University of Iowa Hospitals and Clinics presented a study following 59,614 women over 8.7 years in the Women’s Health Initiative Observational Study. The study found a 30% increase risk of cardiovascular events (heart attacks and strokes) in those drinking two or more diet drinks daily. The benefits for heart attack, stroke, diabetes, and metabolic syndrome were similarly elusive. Artificial sweeteners are not good. They are bad. Very bad. 

Despite reducing sugar, diet sodas do not reduce the risk of obesity, metabolic syndrome, stroke, or heart attacks. But why? Because it is insulin, not calories, that ultimately drives obesity and metabolic syndrome.

The important question is this: Do artificial sweeteners increase insulin levels? Sucralose raises insulin by 20%, despite the fact that it contains no calories and no sugar. This insulin-raising effect has also been shown for other artificial sweeteners, including the “natural” sweetener Stevia. Despite having a minimal effect on blood sugars, both aspartame and Stevia raise insulin levels higher even then table sugar. Artificial sweeteners that raise insulin should be expected to be harmful, not beneficial. Artificial sweeteners may decrease calories and sugar, but not insulin. It is insulin that drives weight gain and diabetes.”

So there you have it; the fact is, if you want to lose body fat, you not only gotta get off the sugar, you gotta get off the artificial sweeteners, too. They may not spike your blood glucose like sugar does (and, of course, refined carbohydrates), but they’ve still been shown to spike your insulin—and it’s insulin that causes obesity and diabetes!

Damn…diet soda might well be the hardest habit/addiction I need to break yet!

UPDATE: someone raised the question of whether “pure” Stevia will spike insulin, after searching online he was unable to find a single source stating this. So I reviewed the book again, and it is rather ambiguous regarding this distinguishing factor.

Here’s what Dr. Fung initially writes about Stevia:

“Stevia is extracted from the leaves of Stevia rebaudiana, a plant that is native to South America. It has 300 times the sweetness of regular sugar and minimal effect on glucose. Widely used in Japan since 1970, it has recently become available in North America. Both agave nectar and sweeteners derived from Stevia are highly processed. In that regard, they are not any better than sugar itself—a natural compound derived from sugar beets.”

And that’s where he leaves it. So apparently, his claim is that processed Stevia will induce elevated glucose much like processed sugar, which in turn prompts the insulin response—whereas artificial sweeteners have been shown to elevate insulin without the elevated glucose.

It sounds to me like the processing may be the problem, as it is with processed carbs, wherein the fat, protein, and fiber is removed. Net carbs = total carbs – fiber, so removing the fiber during processing skyrockets the net carbs…so perhaps pure Stevia contains enough fiber to negate the carbs, and thus has a minimal effect on glucose….while processed Stevia does not? Makes sense, though that’s not specifically stated by the author.

So now I wonder: do I need to start looking at Stevia products, see if I can determine processed vs. natural or pure Stevia. For instance, is Stevia leaf extract considered “processed” or “pure”?

On the other hand, I checked, and Mark Sisson of Primal Blueprint fame—considered one of the top experts in the paleo diet arena—recommends both Stevia and monk fruit as acceptable alternative sweeteners in his book The Keto Reset Diet Cookbook, which being keto-focused, would obviously consider both glucose and insulin spikes, and has apparently determined them to be negligible with the use of these two natural sweeteners.

So, further investigation on this slight detail—is it processed, pure, or ALL Stevia that causes the alleged insulin spike?— will be needed; I will further update this article if I discover any further enlightening information.

FINAL UPDATE: Upon locating both the study the author cites, as well as another article interpreting the same study, I’ve concluded that the author’s claims concerning the use of Stevia are unfounded, and so I’ve added statements from both the study and the additional article at the beginning of this article.

My only other speculation is that perhaps the author is merely stating that Stevia does raise blood insulin levels slightly, but not as much as aspartame or sucrose (sugar), and if your goal is to keep your insulin levels as low as possible, you should avoid using Stevia, along with aspartame and sugar. Perhaps that’s what he’s advising.

As for me, I intend to continue using Stevia, but avoid aspartame if I can.