The 12-week clinical study of 303 participants is the first prospective, randomized clinical trial to directly compare the effects of water and diet beverages on weight loss within a behavioral weight loss program. Conducted simultaneously by researchers at the University of Colorado Anschutz Health and Wellness Center in Aurora, Colorado and Temple University’s Center for Obesity Research and Education in Philadelphia, the study shows subjects who consumed diet beverages lost an average of 13 pounds – 44 percent more than the control group, which lost an average of 9 pounds. More than half of the participants in the diet beverage group —64 percent — lost at least five percent of their body weight, compared with only 43 percent of the control group. Losing just five percent of body weight has been shown to significantly improve health, including lowering the risk of heart disease, high blood pressure and type 2 diabetes.
“There’s so much misinformation about diet beverages that isn’t based on studies designed to test cause and effect, especially on the internet,” said John C. Peters, co-author of the study and the chief strategy officer of the CU Anschutz Health and Wellness Center. “This research allows dieters to feel confident that low- and no-calorie sweetened beverages can play an important and helpful role as part of an effective and comprehensive weight loss strategy.”
Study participants were randomly assigned to one of two groups: those who were allowed to drink diet beverages, such as diet sodas, teas and flavored waters, or those who were in a control group that drank water only. With the exception of beverage options, both groups followed an identical diet and exercise program for the duration of the study.
In addition to losing 44 percent more weight than the control group, the diet beverage group also:
Reported feeling significantly less hungry;
Showed significantly greater improvements in serum levels of total cholesterol and low-density lipoprotein (LDL) — the so-called “bad” cholesterol; and
Saw a significant reduction in serum triglycerides.
Both diet soda and water groups saw reductions in waist circumference, and blood pressure.