Aspartame is often claimed to mess with your blood sugar and insulin.
But what does science really say about how it affects your body, particularly your glucose levels, insulin response, and the hormones that control your appetite?
Key Points:
- A new review analyzed 100 experiments to investigate how aspartame affects glucose and insulin in humans.
- The findings suggest that aspartame has little to no effect on either blood glucose or insulin.
- Despite the large number of studies, the overall certainty of the evidence for these (non)effects was determined to be “very low” due to variations in study methodologies and some concerns about bias.
New Aspartame Study
Aspartame is a name that pops up frequently in discussions about sugar substitutes and artificial sweeteners. For decades, this little packet of (almost) non-calorie sweetness has been used in diet sodas, sugar-free snacks, and a host of other products, promising the sweetness without the calories of sugar.
In those discussions, aspartame often ends up in the hot seat. But is it a silent saboteur of your metabolism or no worse for your blood sugar than water?
A new systematic review and meta-analysis, published in the Advances in Nutrition journal, dug through every controlled intervention study in humans that investigated these effects.1
What Did the Scientists Do?
The study screened more than 11,000 studies and zeroed in on 101 controlled trials examining how aspartame affects glucose, insulin, and those little hormones that control your appetite.
They looked at the short, medium, and long term. They included healthy folks, people with diabetes, and even those who claim to be aspartame-sensitive. No stone (or diet soda) was left unturned.
What Did They Find?
The search was fruitful, identifying 101 articles detailing a whopping 100 different experiments. These studies varied greatly:
- 79 were acute (less than a day), 8 medium-term (2–30 days), and 13 long-term (over 30 days).
- They included healthy adults, individuals with “aspartame sensitivity”, and those with compromised glucose metabolism.
- The way aspartame was given and the comparators used also differed a lot across studies.
At the end of the day aspartame didn’t do much of anything, at least not in a bad way.
- Glucose & Insulin: In short-term studies (within a day), aspartame had no noticeable impact on blood sugar or insulin levels compared to water or other low-calorie sweeteners. When stacked against sugar, aspartame led to lower glucose and insulin responses (as expected, as aspartame itself doesn’t contribute calories or sugars).
- Appetite Hormones: Only a few studies looked at other appetite-regulating hormones, but again, nothing dramatic happened. No hunger hormones went haywire.
- Long-Term Effects: Over weeks and months, aspartame still didn’t mess with your metabolism. Measures like HbA1c (a longer-term blood sugar gauge) stayed stable. Aspartame didn’t spike hunger, tank energy, or unleash sugar-craving chaos.
- Special Populations: Even among people with diabetes or those claiming aspartame sensitivity, there was no evidence that aspartame caused trouble.
Note On Study Quality
Despite the large number of studies, the researchers judged the certainty of the evidence for all outcomes in all populations to be “very low”.
That’s because many of the studies had “some concerns” regarding their design or reporting. The wide variation in how the studies were conducted also made it difficult to pool the results.
The Catch?
It’s also worth noting that Ajinomoto Health and Nutrition North America, who makes aspartame, funded this review.
That fact alone will likely make those who are already firmly set in their beliefs against aspartame discard this meta-analysis, but someone has to finance research.
The Bottom Line
Based on this new review and meta-analysis of all the human studies ever published over many decades, the authors conclude that current evidence suggests little to no effect of aspartame consumption on glucose metabolism over the short or longer term.
I don’t think anyone is advocating a 12-pack-a-day diet soda habit, but if you’re using aspartame to cut sugar and calories without fearing for your blood sugar, you’re most likely on safe ground.
