The Blind Spot in the Anti-Soda Crusade

06/13/2015 01:37 pm ET | Updated Jun 13, 2016

Recent efforts to raise awareness about the adverse health effects of sugar prompt an important question: Are so-called "diet" drinks a good alternative?

Campaigns to pass a soda tax and put warning labels on sugar-sweetened beverages are based on strong scientific evidence showing a link between diabetes, obesity and consuming too much sugar.

The dangers of "diet" soda are less clear, but studies linking "diet" soda to weight gain and other long-term health consequences are a rising cause for concern.

The beverage industry argues that good health is about simple math: calories in, calories out. Consumers are left to believe that "diet" soda is healthier simply because it doesn't have sugar or calories.

Reform efforts can reinforce that belief. In 2006, the William J. Clinton Foundation helped broker a deal between schools and the nation's largest beverage distributors to stop selling soda in public schools. An exception was carved out for "diet" sodas in high schools. Policies like these send the message that "diet" soda is a healthier alternative.

But "diet" drinks might not be good for you. While some studies have failed to find a link between diet soda and weight gain, others suggest calorie-free sweeteners do more than just mimic the taste of sugary snacks and drinks on the tongue.

Drinking diet soda regularly, even just one per day, may increase the risk of weight gain, metabolic syndrome, Type 2 diabetes and cardiovascular disease according to a 2013 review of scientific literature conducted by Susan E. Swithers, a behavioral neuroscientist at Purdue University.

A 2015 study published in the Journal of the American Geriatrics Society reported a link between drinking diet soda and weight gain over time. "On average, for each diet soft drink our participants drank per day, they were 65 percent more likely to become overweight during the next seven to eight years," lead researcher Sharon Fowler of the University of Texas Health Science Center at San Antonio said in a release announcing the findings.

A 2013 study of sucralose, better known as Splenda, found that it may affect how the body handles real sugar. The study of 17 obese human subjects published in Diabetes Care found that sucralose triggers the body's insulin response. Making enough insulin to deal with a spike in blood sugar is a good thing, but when the body makes too much it can cause insulin resistance, perhaps leading to Type 2 diabetes.

The findings are disconcerting since sucralose has overtaken aspartame as the sweetener of choice in part because it is perceived as safer. PepsiCo Inc. recently announced it is replacing aspartame with sucralose in Diet Pepsi. Sucralose is a chemically altered form of sugar, originally marketed as a natural alternative to other fake sweeteners when it was introduced in the late 1990s.

In animals, researchers from Purdue University have found that fake sugar can trigger metabolic and hormonal responses that undermine the body's ability to handle real sugar and lead to weight gain. The results were published in 2008 in Behavioral Neuroscience. Another study from Israel's Weizmann Institute of Science published last year in Nature found that artificial sugar interfere with the gut bacteria that help process food. In that study, the mice developed glucose intolerance after consuming artificial sweeteners.

There is much we still don't understand about how artificial sweeteners may affect humans, but a growing body of research suggests turning to diet soda to feed a sugar craving may not be a good bet.

A smart approach is to reduce consumption of sugar, fake or real.