Nutritional Pearls: Do Calorie-Free Sweeteners Cause Obesity?
James is a 47-year-old male who has previously switched from regular soda to diet drinks, believing this will help him lose weight. He recently read something that mentioned how calorie-free sweeteners cause obesity. He wants guidance on whether diet drinks will cause him to gain weight.
How would you advise him?
What is the correct answer?
(Answer and discussion on next page)
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Answer: Diet drinks may encourage long-term weight gain.
Back in May, I had written about a study that seemed to show that drinking beverages sweetened with calorie-free sweeteners would actually help you lose weight.1 The problem, however, is that the study was funded by The American Beverage Association and 2 of the researchers involved had been paid consultants.
More reputable research into the effects of drinking these types of beverages is rather mixed, with some research suggesting that those drinking diet drinks instead of sugar-sweetened beverages were more likely to become overweight or obese over time.2 Research in rats has even suggested that drinking beverages sweetened with calorie-free sweeteners may affect the individual's ability to judge the number of calories actually consumed.
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New Research
A team at Texas Christian University theorized that the effect of these beverages sweetened with non-caloric sweeteners (NCS) might be far more subtle and long term than had previously been thought.3 The designed a set of 3 experiments to assess people's psychological and behavioral responses to consuming beverages sweetened with NCS.
At the start of all 3 of the studies, the participants (all students at the university) were randomly given 1 of 3 drinks in a red plastic cups: regular Sprite, Sprite Zero (sweetened with a NCS), or an unsweetened sparkling water flavored with natural lemon and lime flavorings.
For the first study, the participants consumed their beverage and then were shown different words flashed on the computer screen. They were directed to indicate as quickly as they could whether the word was real word or a non-word by pressing certain keys on the computer keyboard. Three types of words were presented: the name of a high-calorie food (eg, burger, cookie, or pizza), the name of a low-calorie food (eg, celery, apple, or radish), or a non-word (eg, ebusun, ganeap, or tigne).
The second study directed the students to respond to a series of questions about the packaging of 3 items—a bag of M&M's, a bottle of plain water, and a pack of sugar-free gum—after consuming their beverage. After completing the questionnaire, the students were told that they could choose one of the products to take home with them.
For the last study, the panelists consumed their assigned beverage and then were directed to taste as many cookies as they wished from a standardized amount of mini Oreos. Afterward they responded to a survey about their impressions of taste and how satisfied they felt after consuming the cookies.
The Results
The results are quite interesting.
In the first study, individuals who consumed the calorie-free Sprite responded the fastest when high-calorie words were flashed on the screen, suggesting that the brain was primed to respond to high-calorie foods. Response time was not significantly different for the low-calorie or nonsense words.
Furthermore, individuals who consumed the sugar-sweetened beverage or the mineral water had no significant differences in their response time, regardless of the type of word.
In the second study, individuals who drank the NCS beverage were twice as likely as those drinking the sugar-sweetened beverage or the water to decide to take the M&M's home and, in the third study, were least satisfied with the cookies they had eaten, although they liked the taste and ate about as many of the cookies as either of the other 2 groups.
What’s the “Take Home”?
This study found that small effects—such as, being primed to react to higher-calorie foods, making less-healthy choices, and being less satisfied with what people eat along with their diet drink—could lead to long-term weight gain. While further research is needed, it's another indication that your patient’s best bet is still water, coffee (regular or decaf), and tea.
- Harlan T. What The American Beverage Association wants you to think. Dr Gourmet website. http://www.drgourmet.com/bites/2014/052814.shtml. Accessed September 22, 2014.
- Harlan T. Is drinking soda bad for you? Dr Gourmet website. http://www.drgourmet.com/eatinghealthy/soda.shtml. Accessed September 22, 2014.
- Hill S, Prokosch M, Morin A, et al. The effect of non-caloric sweeteners on cognition, choice, and post-consumption satisfaction. Appetite. 2014;83:82-88.