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Dear Dietitian – Do diet sodas cause weight gain instead of loss?

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PICT Leanne McCrate Dear Dietitian
Leanne McCrate, RDN, LD

Dear Dietitian,

I am on a diet, and I usually drink one or two diet sodas a day. A coworker insists that diet sodas cause weight gain instead of weight loss. Is this true?


Dear Suzanne,

Artificial sweeteners, or nonnutritive sweeteners (NNS), made their debut with saccharin in 1884 in Germany. Saccharin is sold in the US under the brand name Sweet’ N Low®. Today there are numerous NNS on the market, some of which are aspartame (NutraSweet® and Equal®), sucralose (Splenda®), and stevia (Truvia® and Stevia In The Raw®) . 

Studies are mixed when it comes to artificial sweeteners and weight loss. In a randomized trial, 303 overweight participants were instructed to drink 24 ounces of water or artificially- sweetened beverages. Both groups were on a weight loss plan. At the end of three months, those who consumed the artificially-sweetened drinks lost more weight (13 pounds) than those who drank water (9 pounds). The increase in weight loss is attributed to the opportunity to satisfy a sweet tooth with something that has no calories (1). It is important to point out that the American Beverage Association funded this study, which may be a conflict of interest.

There is some concern that NNS lead to weight gain. An eight-year study found a strong link between people who use artificially-sweetened beverages and weight gain. Those who drank the most diet soft drinks gained the most weight. This study was observational, which does not prove cause and effect. Of note, most people who drank diet soda were overweight at the beginning of the study compared to those who didn’t use artificial sweeteners. They also identified themselves as dieters, and long-term weight gain is associated with chronic dieting (2).

Professional organizations differ in their opinions of NNS. The US Dietary Guidelines cite “insufficient evidence to recommend the use of low-calorie sweeteners as a strategy for long-term weight loss and weight maintenance” (3). The American Heart Association and the American Diabetes Association have released similar statements. However, the position of the Academy of Nutrition and Dietetics is that “consumers can safely enjoy a range of nutritive sweeteners and nonnutritive sweeteners (NNS) when consumed within an eating plan that is guided by current federal nutrition recommendations, such as the Dietary Guidelines for Americans, as well as individual health goal and personal preference” (4).

Nutrition experts make a strong point in that the risks associated with consuming a high-sugar diet are greater than the risks of consuming nonnutritive sweeteners. In the context of a weight loss plan, the use of NNS will likely help you reach your goal.

Until next time, be healthy!

Dear Dietitian


  1. Seaborg, E. Sweet & lowdown: artificial sweeteners & weight gain. 2017 January. Retrieved from
  2. Rubin, R. Do artificial sweeteners help you lose weight? -Research examines the relationship between nonnutritive sweeteners and weight loss. Today’s Dietitian, 2011 September; 13; (9): 14. Retrieved from
  3. US Dietary Guidelines, 2015-2020 (2020 Jan. 30). Retrieved from
  4. Position of the academy of nutrition and dietetics: use of nutritive and nonnutritive sweeteners. 2012 May. J Acad Nutr Diet. 2012;112:739-758. 

doi: 10.1016/j.jand.2012.03.009

Leanne McCrate, RDN, LD, is an award-winning dietitian based in St. Louis, Missouri. Her mission is to educate consumers on sound, scientifically-based nutrition. Do you have a nutrition question? Email her today at Dear Dietitian does not endorse any products, health programs, or diet plans.