Unless you have had your head in the sand or living in major denial – you have heard that diet soda is purportedly bad for us. Perhaps as bad as its sugar-laden counterpart. How can this be? Why can’t we substitute diet soda for regular soda and reap the benefit of cutting out all that sugar while satisfying the craving for our favorite beverages? For those of us who have spent all this time getting used to the flavor of the diet version that is supposed to be so much better – even if there could be some ill effects – can’t we just live with them?

Diet soda

The answer is a pretty resounding, ‘no.’ After years of research on many fronts, it’s for good reason.

Artificial sweeteners added to diet drinks (and other foods) to give them their signature sweetness may be fooling us, but not our bodies. We consume the artificially sweetened drink (food, etc.) and are initially satisfied with the taste. But behind the scenes our brains are waiting for a signal they’ll never get. Consuming sweet flavors activates pleasure pathways in the brain. Once they are turned on, they want more. When our calorie consumption matches the sweetness our brains perceive, that pleasure pathway gets another hormonal message to shut down – and the cravings stop.

What happens when the calories and the sweetness don’t match? The pathway stays wide open – and the craving for additional sweets continues. Our strategy to do good, by consuming fewer calories, backfires as the cravings ramp up and we find ourselves eating even more than we would have in the first place, chasing the balance.

It doesn’t stop with weight gain either. Other health problems strongly linked with artificial sweeteners include decreased insulin sensitivity, heightened cardiovascular issues, and Alzheimer’s disease.

Insulin sensitivity is a term used to describe how sensitive our bodies are to the effects of insulin. Insulin is the hormone that tell our cells to take in the glucose (sugar) from our blood. When our insulin sensitivity is low, our body’s ability to balance blood sugar is compromised. We try to make up for this by producing more insulin. Too much insulin can create more health problems such as high blood pressure, heart disease, obesity, osteoporosis, and the list goes on.[1]

The research is compelling and there is no shortage of studies outlining the danger of continuing to drink the diet soda. One study looked at the relationship between drinking diet soda and cardiovascular events occurring in women over 60. For more than 5 years, over 50,000 women were followed in an attempt to find a correlation. Those that consumed 2 or more diet drinks daily had a significantly greater incidence of cardiac events (heart attack, stroke, even death) than those who chose diet drinks much less frequently or not at all.[2]  Another study found a strong correlation between those who drink both diet and non-diet soda and incidence of stroke.[3] Interestingly, this seems to be a bigger problem for women than for men – although the results are certainly compelling for both.

More recent research related to gut microbes has shown an interesting cause and effect relationship between artificial sweeteners and their effect on our intestinal microflora. It appears the artificial sweeteners are killing off some gut bacteria, allowing others to flourish and by throwing off the balance are directly contributing to glucose intolerance.[4] Glucose intolerance is associated with insulin resistance, insulin sensitivity (which we talked about earlier) and increased risk of cardiac issues. When you are insulin resistant, your cells have a hard time getting the message from the insulin to take in glucose, raising your levels of blood sugar.

No matter how you slice it, the argument for diet soda continues to get weaker as time passes, additional research is done and there is more data available to demonstrate both how it affects us and how our bodies can change when we consume it regularly. If you are still drinking diet soda (or any soda), consider some sparkling water instead to get the bubbles without all the scary side effects. But be sure to read the label, artificial sweeteners can show up in the unlikeliest of places!

Written by Samantha, Starkel Nutrition intern, BS in Nutrition candidate at Bastyr University


  1. http://www.diabetes.co.uk/insulin/insulin-sensitivity.html
  2. Vyas, A., Rubenstein, L., Robinson, J., Seguin, R. A., Vitolins, M. Z., Kazlauskaite, R., . . . Wallace, R. (2015). Diet drink consumption and the risk of cardiovascular events: A report from the women’s health initiative. Journal of General Internal Medicine, 30(4), 462-468. doi:http://dx.doi.org/10.1007/s11606-014-3098-0
  3. Bernstein A, de Koning L, Flint A, Rexrode K, Willett W. Soda consumption and the risk of stroke in men and women. American Journal of Clinical Nutrition. 2012;95(5):1190-1199. doi:10.3945/ajcn.111.030205.
  4. Suez, J., Korem, T., Zeevi, D., Zilberman-Schapira, G., Thaiss, C. A., Maza, O., . . . Elinav, E. (2014). Artificial sweeteners induce glucose intolerance by altering the gutmicrobiota. Nature, 514(7521), 181-6.