A recent weight loss study involving 303 subjects will be published in the June issue of Obesity. The study showed that diet soda may actually help people lose weight, which contradicts previous studies that stated otherwise. James Hill, Ph.D., who is the executive director of the Anschutz Health and Wellness Center at the University of Colorado and a co-author of this study, stated in a press release that this study “clearly demonstrates” that diet drinks can help people lose weight, negating the “myths in recent years” that they promote weight gain. He reported that subjects who drank diet soda lost 44 percent more weight – an average of 13 pounds – than those who did not drink diet soda, who lost an average of nine pounds. Subjects were randomly assigned to one of two groups: Those who were allowed to drink diet beverages, or those who were in a control group that drank water only. Aside from the beverage options, both groups consumed the same diet and performed the same exercise program during the 12-week study, which was funded by the American Beverage Association, whose members include the Coca-Cola and Pepsi bottling companies. It is not all good news, however. Despite the recent study’s weight loss claim, drinking diet soda and similar beverages with artificial sweeteners to help lose inches has some hidden risks that could harm overall health.
Susan Swithers, Ph.D., who is a professor of behaviorial neuroscience at Purdue University, wrote a peer-reviewed paper that was published in Trends in Endocrinology and Metabolism (September 2013) that cautioned the effects of consuming artificial sweeteners in the long run. Swithers stated on CNN that short-term studies do not reveal the long-term effects that diet beverage consumption can have in relation to health and weight loss. Previous studies that examined people who drank diet soda for seven, 10, or more years have higher risks for cardiovascular disease, metabolic syndrome, weight gain, and type 2 diabetes. However, these studies show a correlation, but not necessarily a causation.
“There are a couple of studies in humans that have looked at how the brain responds to sugar or artificial sweeteners. Those data indicate that people who drink diet sodas have different patterns of brain activity compared to people who don’t drink them,” Swithers told the Guardian Liberty Voice in an online interview. In her report, Swithers highlighted that artificial sweeteners, such as saccharin and aspartame, in diet beverages can change the way the brain controls food intake and maintains energy balance. In human studies, brain scans showed that sucrose – a type of sugar – activates “dopaminergic midbrain areas related to reward or pleasantness,” while sucralose in artificial sweeteners “reduced activation in other taste-related pathways.”
John C. Peters, who co-authored the study and is the chief strategy officer of the Anschutz Health and Wellness Center, stated that the misinformation about diet beverages is not based on studies that are designed to “test cause and effect.” The Anschutz research shows that diet beverages can play a helpful role in weight loss. Although both diet soda and water groups had reduced their waist circumference and blood pressure, the former group reported feeling less hungry, had improved serum levels of total cholesterol and low-density lipoprotein (LDL) -or “bad cholesterol,” and had lower serum triglycerides.
The Anschutz study adds on to an existing body of research that states that diet beverages can help with weight loss, not hinder it. The press release mentioned two peer-reviewed studies that were published in the American Journal of Clinical Nutrition by researchers from the University of North Carolina in 2012 and 2013. In one of the studies, non-dieting subjects were randomly assigned to drink diet beverages or water. Six months later, the diet beverage group had a greater weight loss (five percent) than the water group. The first group had a greater reduction in dessert consumption than the water group.
Even so, there are some concerns with the Anschutz study. “This study used a highly selected population of individuals who were already consuming diet sodas. As a result, conclusions can only be drawn about the effects of changing diet soda intake patterns,” said Swithers. “Moreover, in this study, those who were advised not to consume diet sodas were still consuming artificial sweeteners in their food (at least they were not prohibited from doing so; the study does not indicate that any measures of what people actually ate were collected). This means that we really can’t even draw any conclusions about artificial sweeteners. And the study only lasted for three months.”
The objective about such studies should not just be about weight loss; it should be more about keeping the weight off. Swithers added, “Finally, weight loss isn’t really what we should be focusing on. We should be concerned about the health consequences associated with obesity, like diabetes, heart disease, high blood pressure, and stroke. Long-term (years to decades) data indicate that those who are consuming diet sodas have increased risk for these outcomes. While this doesn’t prove that the diet sodas are the cause of these risks, it’s hard to look at those outcomes and make arguments that they benefit people.”
Whether or not diet beverages and artificial sweeteners could help or hinder weight loss, consumers should still weigh the hidden risks that current evidence shows. Another factor to consider is the funding source of the Anschutz research. A meta-analysis and systematic review of 88 soda consumption studies that was published in April 2007 of American Journal of Public Health revealed that the average overall effect size for industry-funded studies was significantly smaller than the average effect size for non-industry-funded studies. For example, 80 percent of the studies that support the usage of the fat substitute Olestra were funded by the food industry. However, 21 percent of the neutral studies and 11 percent of critical studies of Olestra have been funded by the industry. This may be cause for additional scrutiny in the Anschutz study’s outcome.
By Nick Ng