I have been a Diet Coke drinker since high school. It’s refreshing. It’s fizzy. And it tastes good. I love it in the way others love coffee. So every time the sweetener in my beverage-of-choice is accused of something, I brace myself for the inevitable – I’m going to have to quit drinking Diet Coke. But my favorite drink and I always seem to get a reprieve. Cancer – nope. Brain tumors – nope. Memory issues – nope.

Now it seems researchers are wondering if artificial sweeteners are contributing to our weight problems. This might be it, folks.

These ten (okay 15) pounds I need to shed? My diet drink habit might be preventing it. In fact, it may have caused the weight gain to begin with. (Notice how might and may are in italics. That’s going to be important in a moment.)

Back in the 80’s, researchers in San Antonio started an epidemiological study to look at obesity and glucose intolerance in Mexican-Americans. They asked the subjects questions about their lifestyle and followed them for years to find associations between lifestyle and health issues and how they compared to non-Hispanic white subjects.

In 2003, researchers looked at data from this study about artificial sweetener use. In 1979 individuals in the study were questioned about their consumption of artificially sweetened beverages. Their height and weight were measured. Over 3600 of them were reexamined seven to eight years later.

Things didn’t go so well for the diet beverage drinkers over those seven or eight years. They were more likely to be overweight or obese than those who did not consume artificially sweetened beverages. Almost twice as likely, in fact, whether they were overweight to begin with, or not.

Now remember when I said might and may before? That’s because this study is an epidemiological study, meaning subjects weren’t randomly broken up into groups that would consume or not consume artificial sweeteners. That would help control for confounding factors. Instead, the study subjects’ natural choices were simply recorded. So any number of factors might account for these results.

It could be that diet beverages are a sign of a generally bad diet. (Think having a diet Coke with your Quarter-pounder and fries.) Maybe it often accompanies excess consumption of sweets because of a false sense of healthfulness. It could represent a sweet tooth that predisposes them to eat in a certain way. Any number of factors could account for these results. The best we can say from this study is drinking artificially sweetened beverages is associated with weight gain, not that it causes weight gain.

Does that make you feel better about ordering a diet drink at lunch today? Me neither.

One more study gives me pause about my Diet Coke habit. This study was done in rats, so we are far from being able to draw any conclusions. But it does raise questions that deserve investigation.

In summary, rats were fed artificial sweeteners. This resulted in impaired glucose tolerance (a risk for diabetes). It also changed the rats’ microbiomes. Remember, the microbiome is the world of microbes or bacteria that inhabit our guts. The researchers then cleaned out another group of rats – completely killed off their microbiome - and transplanted the altered microbiome from the artificial sweetener-eating rats. And guess what? Their glucose metabolism was affected in the same way as the rats that ate the sweeteners.

The researchers did a similar test in healthy human subjects, minus the fecal transplant. They found that those who had impaired glucose metabolism after consuming artificial sweeteners also had an altered microbiome. This part of the research only included seven individuals and the sweetener only affected four. We are far from able to draw conclusions here.

But it is interesting and raises lots of questions. Do artificial sweeteners somehow disrupt our normal gut bacteria, triggering a cascade of events that lead to glucose issues and weight problems? It may be. We know that the microbiome is critical to good health, so it’s not out of the realm of possibility. More research in humans and we might understand the full implications of this information.

In the mean time, the question I have to ask myself is if my Diet Coke is helping my health in any way. It’s a question that’s easy to answer. Not only is it not doing me any favors, but it might be doing me harm. I don’t need to wait for more research to make this change.

Amy Rogers MD is not a practicing physician and nothing written here should be taken as medical advice from either Amy or AssetBuilder. Medical decisions should be made with care in consultation with your health care provider.