FRIDAY, Sept. 11, 2015 (HealthDay News) -- People who drink diet soda to cut back on calories may be undoing their own good intentions, a new study suggests.
Researchers report that those who opted for low-calorie soft drinks ended up eating more foods loaded with sugar, salt, fat and cholesterol.
However, the study did not prove that drinking diet sodas causes a person to eat more unhealthy foods.
"It may be that people who consume diet beverages feel justified in eating more, so they reach for a muffin or a bag of chips," study author Ruopeng An, a kinesiology and community health professor at the University of Illinois at Urbana-Champaign, said in a university news release. "Or perhaps, in order to feel satisfied, they feel compelled to eat more of these high-calorie foods."
It's also possible that people who feel badly about eating unhealthy foods assuage their guilt by drinking diet beverages, An added.
"It may be one -- or a mix -- of these mechanisms," he said. "We don't know which way the compensation effect goes."
The American Beverage Association (ABA) said the researchers didn't prove their theories.
"This study, based on surveys of Americans and their diets, proved something that is well known: many people eat things that 'are not required by the human body,' " William Dermody Jr., vice president of policy at the ABA, said in a statement.
"But from that unsurprising observation, the author leaps to the unproven and unsubstantiated claim that diet soda 'may' be why people choose to eat a range of other foods such as french fries or doughnuts rather than eat exclusively from the major food groups," Dermody added.
Dermody said previous research has shown that diet sodas are an effective tool to help people lose weight and maintain weight loss.
In conducting the study, the researchers examined government data collected on the eating habits of more than 22,000 adults in the United States. The participants were asked to report everything they ate or drank on two different days.
Specifically, total calorie intake and the participants' choice of beverages -- including coffee, tea, sugar-free drinks, sugary beverages and alcohol -- were analyzed. The researchers also considered consumption of discretionary foods, which are calorically dense but low in nutritional value, such as cookies, ice cream, fries, pastries and chocolate.
The study found that those who drink diet beverages may not actually be "saving" any calories because the foods they eat have more sugar, salt, fat and cholesterol.
More than 90 percent of those included in the study ate discretionary foods regularly, which amounted to about 482 calories per day, according to the study, which will be published in an upcoming issue of the Journal of the Academy of Nutrition and Dietetics.
About 97 percent of the participants had at least one of the five types of beverages daily, the findings showed.
More than half of the participants drank coffee. The next most popular beverages were sugary drinks, which were consumed by 43 percent of those in the study. Tea was the beverage of choice for 26 percent of the participants, 22 percent drank alcohol and 21 percent chose diet beverages.
Drinking alcohol was associated with consuming an extra 384 calories daily, while sugary drinks led to the consumption of 226 more calories. Coffee was linked to an extra 108 calories per day, and diet beverages were tied to 69 additional calories. Tea was associated with an extra 64 calories, the study found.
Although coffee and diet beverage drinkers consumed fewer total calories daily than those who drank alcohol or sugary drinks, they got a larger percentage of their total calories from unhealthy foods, the researchers found.
The obese adults in the study who drank diet beverages also got more calories from discretionary foods than people who were a normal weight but drank sugary beverages. The study authors concluded that opting for diet drinks may not help people control their weight if they don't eat healthy foods and consider portion sizes.
"If people simply substitute diet beverages for sugar-sweetened beverages, it may not have the intended effect because they may just eat those calories rather than drink them," An said in the news release. "We'd recommend that people carefully document their caloric intake from both beverages and discretionary foods because both of these add calories -- and possibly weight -- to the body."
The U.S. National Institutes of Health has more about diet soda and body weight.