No Need to Stop Diet Drinks to Lose Weight in Short Term

Marlene Busko

May 29, 2014

In a 12-week weight-loss program, individuals who continued to consume diet beverages lost 1.86 kg more and reported feeling less hungry than those who switched to water. But it is too early to routinely recommend these beverages for weight loss, an accompanying editorial cautions.

"These results strongly suggest that [nonnutritive sweetened] beverages can be part of an effective weight-loss strategy and that individuals who desire to consume them should not be discouraged from doing so because of concerns that they will undermine short-term weight-loss efforts," lead author John C. Peters, PhD, from the Anschutz Health and Wellness Center, University of Colorado, in Aurora, and colleagues write.

"The use of the word 'strongly' is a little too strong for what the design and findings of the study actually showed," editorialist Stephen D. Anton, PhD, from the department of aging and geriatric research, University of Florida, in Gainesville, countered in a comment to Medscape Medical News. "I don't think we have enough information yet to inform us to use diet drinks [in weight-loss programs], but it suggests that there is no harm — no negative effect — on short-term weight-loss outcomes in people who are regular consumers."

He cautions in his editorial, however, that he would not widely recommend their use in individuals who do not regularly consume such beverages.

The study was published in the June issue of Obesity.

Weight Loss With Diet Drinks Still Controversial

A large body of evidence confirms that drinking sugar-sweetened beverages promotes weight gain, but the potential value of replacing these with artificially sweetened drinks as opposed to water remains controversial. For example, different studies have reported that people who consumed artificially sweetened foods and beverages had a wide variety of reactions with respect to appetite, including increases, no changes, and decreases.

To investigate this, the researchers designed a 1-year prospective, randomized trial with a 12-week intervention, followed by 9 months of a weight-maintenance phase.

After screening 506 people, they enrolled 151 participants at the University of Colorado and 157 participants at Temple University, in Philadelphia, Pennsylvania, between October 2012 and April 2013. The participants had an average age of 48, and 82% were women. About 28% were African American, and 68% were white. At baseline, they had body mass index (BMI) of 34 and weighed 93 kg, on average.

The study subjects had a recent stable weight, were sedentary, and had been consuming at least 3 nonnutritive sweetened beverages, including artificially sweetened diet sodas, teas, or flavored water, each week.

They were randomized to drink at least 24 fluid oz a day of water or nonnutritive sweetened beverages. A typical diet soda is 12 oz (355 mL). The participants received coupons to redeem for bottled water or diet drinks.

Participants in the group assigned to drink water were allowed to eat artificially sweetened candies, yogurt, cookies, ice cream, gelatin, pudding, or other foods or chew artificially sweetened gum. But they "could not intentionally add [nonnutritive sweeteners] (examples: aspartame — NutraSweet or Equal; sucralose — Splenda; stevia — Truvia; as well as diet creamers) to beverages such as coffee," Dr. Peters and colleagues explain.

Both groups participated in the Colorado Weigh behavioral-intervention weight-loss program, which consisted of 1-hour weekly group meetings led by a registered dietician or a clinical psychologist, where topics such as food labels, portion sizes, and physical activity were discussed and participants were weighed.

The subjects were given a goal of losing 1 to 2 pounds a week and instructed to up their exercise by 10 minutes each week with a goal of reaching 60 minutes/day 6 days/week. They received $75 for completing the week-12 assessment and $50 for completing at least 9 weeks of daily food and beverage logs.

About 96% of participants in each group reported meeting their targeted daily beverage consumption. Almost all subjects (92%) completed the weight-loss program.

At week 12, on average, participants who had been drinking artificially sweetened beverages lost 5.95 kg, whereas those who had been drinking water lost 4.09 kg. Both groups upped their physical activity by about 1.5 hours a week. Participants in the group that drank artificially sweetened beverages reported feeling slightly less hungry than those in the other group, although the absolute change in hunger was small.

"Unanswered Questions"

The study is "commendable" in that it was conducted at 2 sites, included a diverse population, and had excellent compliance and retention rates, Dr. Anton writes.

However, "there are a few important questions that are left unanswered," he cautions. First, this analysis covered short-term outcomes, and "we've shown over and over again we can produce short-term weight loss, and long-term weight loss is very difficult."

Second, the published study did not provide information about the amount of artificial sweeteners that were actually consumed in the 2 groups.

Third, the mechanism for the weight loss remains a mystery. Since the treatment groups had similar changes in physical activity, the difference in weight loss is likely due to a different caloric intake. "Unfortunately, no information is provided on participant's caloric intake or adherence to dietary recommendations," he pointed out.

Last, the study did not determine whether different nonnutritive sweeteners had different metabolic effects.

"We need to really understand why and what differentiates the 2 groups and why the results of this study are different from other studies," Dr. Anton writes. "Until such data become available, it is advised that [nonnutritive sweeteners] not be widely recommended in weight-loss programs, particularly for individuals who do not regularly consume them."

The study was fully funded by the American Beverage Association. Peters received consulting fees from the Coca-Cola Company outside of the submitted work. Disclosures for the authors are listed in the article. Anton is supported by the Thomas H. Maren Foundation and the University of Florida's Claude D. Pepper Older Americans Independence Center and the Clinical and Translational Science Institute.

Obesity. 2014;22:1415–1421, 1413–1414. Article, Editorial

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