Can You Get Fat From Drinking Diet Soda?


A popular strategy for loosing weight is swapping sugary soft drinks for zero-calorie diet soda. Many health, fitness, and diet gurus advice people to drink diet soda to loose weight quickly. All the taste, zero the calories. Sounds to good to be true, right? It may indeed be to good to be true! Recent news articles reported on a growing body of evidence that no- and low-calorie sweeteners may come with health concerns, including weight GAIN. That sounds counter-intuitive? How can that be? And is it true? ScienceChecker comes to the rescue and checks it out for you!

Artificially-Sweetened Beverages (ASBs), commonly known as light or diet drinks, have been quite the rage ever since those first light series of Pepsi and Coca Cola products in the 60s hit the market and continue to be an ever more broadly consumed product. Today it is impossible to imagine a world where diet drinks and products are not everywhere in the public eye, routinely promoted as part of a health-conscious, low calorie diet or a healthy alternative for their sugary big brother (regular soda).

Over the past few decades, the effect of drinking diet soda, and the artificial sweeteners related to their intake, on weight and weight-related health issues such as type II diabetes have been extensively studied. And while companies producing diet drinks have their own positively focused ‘research’ on them*, independent, systematic scientific research is yet to find solid evidence that these sugar-free alternatives help to maintain a healthy Body Mass Index (BMI), prevent weight gain or reduce the risk of type II diabetes. The “promise” of health benefits from drinking diet soda clearly lacks consistent scientific evidence.

In fact, there are results from a range of studies that suggest that diet drinks may actually make things worse if you are interested in using them as a dietary tool (Golditz et al., 1990; Fowler et al., 2008). How is this possible? While there are several theories about the counterintuitive association between artificial sweeteners and weight gain, there is no direct evidence for any of these mechanisms yet.

One popular mechanism currently under investigation is that, while ASBs effectively reduce the amount of calories in your drink, these drinks still stimulate sweet taste receptors and appetite. In other words, the sensation of sweetness in the absence of caloric intake may “screw up” our body, because it has learned to expect energy (=calories) when tasting something sweet. As a result, this may lead to more compensatory eating and people effectively consuming more calories on a daily basis when compared to a diet that includes sweetened drinks instead. Additionally, work with animals has demonstrated that artificial sweeteners can alter gut microbiota and, in turn, can lead to overeating, weight gain and impaired blood glucose regulation. Recently, this effect on gut microbiota has been shown in humans too (Suez et al., 2014).

Now does this mean that artificially sweetened beverages, when used moderately, are inherently bad? Certainly not! All of the low caloric sweeteners that are currently in use have gone through decades of scientific review. Importantly, our general high sugar, fat and salt-containing diets as well as a more sedentary lifestyle are all additional, important contributing factors to a general rise in obesity, type II diabetes and hearth issues.

However, ASBs are certainly not some magical ingredient you can replace regular sweetened drinks with in order to turn one’s diet or lifestyle around. That (unfortunately) will still take old school effort, self-control, a bit of exercise and sweat, and perhaps a few more glasses of regular water instead of sweetened, regularly or artificially, beverages.

So if you want to loose weight, go for drinking water, not diet soda. Just in case.

Conclusion: POTENTIALLY TRUE. Initial evidence available, but more research necessary for stronger conclusions and underlying mechanisms.

* While a recent food-industry sponsored meta-analyses (Miller & Perez, 2014) concluded that artificially sweeteners may be beneficial for short-term weight loss, this study was heavenly criticized by other researchers not sponsored by the food-industry. Two independent researchers even published a letter questioning the research strategies of the meta-analyses (Pan & Hu, 2014).


Colditz GA, Willett WC, Stampfer MJ, London SJ, Segal MR, Speizer FE. Patterns of weight change and their relation to diet in a cohort of healthy women. Am J Clin Nutr. 1990; 51:1100–1105.

Fowler SP, Williams K, Resendez RG, Hunt KJ, Hazuda HP, Stern MP. Fueling the obesity epidemic? Artificially sweetened beverage use and long-term weight gain. Obesity (Silver Spring, Md.) 2008; 16:1894–1900.

P.E. Miller, V. Perez. Low-calorie sweeteners and body weight and composition. A meta-analysis of randomized controlled trials and prospective cohort studies
The American Journal of Clinical Nutrition, 100 (3) (2014), pp. 765-777.

Pan A., Hu F.B. Question about a recent meta-analysis of low-calorie sweeteners and body weight. The American Journal of Clinical Nutrition, 100 (6) (2014), p. 1604.

J. Suez, T. Korem, D. Zeevi, G. Zilberman-Schapira, C.A. Thaiss, O. Maza, et al.Artificial sweeteners induce glucose intolerance by altering the gut microbiota
Nature, 514 (7521) (2014), pp. 181-186.