Diet Beverages & Artificial Sweeteners

There are generally two questions regarding low-calorie sweeteners:
  1. How effective are they regarding weight loss?
  2. Do they have any negative side effects?

Effectiveness

The answer to the first question is fairly effective Rogers Miller:

  • Some RCTs gave people water, diet beverages, or non-diet beverages and then let them eat as much as they wanted. The non-diet group consumed significantly more, while there was no difference between thee water and diet groups.
  • Long-term RCTs find that diet beverages cause weight loss relative to non-diet beverages and also cause weight loss relative to water.

Side Effects

Seeing as I'm not a doctor (of either kind), I think the wisest course of action is to first quote the Mayo Clinic Zeratsky:

Drinking a reasonable amount of diet soda a day, such as a can or two, isn't likely to hurt you. The artificial sweeteners and other chemicals currently used in diet soda are safe for most people, and there's no credible evidence that these ingredients cause cancer.

Some types of diet soda are even fortified with vitamins and minerals. But diet soda isn't a health drink or a silver bullet for weight loss.

Although switching from regular soda to diet soda may save you calories, it's not yet clear if it's effective for preventing obesity and related health problems in the long term.

Healthier low-calorie choices abound, including water, skim milk, and unsweetened tea or coffee.

As Zeratsky alludes to, a contingent of people once thought that aspartame (an artificial sweetener) causes cancer, though the FDA never agreed Aspartame controversy. However, in truth, a review found no effect in RCTs on rodents Mallikarjun, contradicting the chief evidence used to justify the link.

At this point, the only real evidence in favor is the correlations between artificial sweetener consumption and cancer, but the signs on those correlations are quite mixed Mishra, muddling already quite already weak (correlational) evidence.

More generally, a literature review Lohner found

Overall there is no conclusive evidence for beneficial and harmful effects on [appetite, cancer, diabetes, dental cavities, weight gain, or obesity] outcomes.

and another found "there is no strong clinical evidence for causality regarding artificial sweetener use and metabolic health effects" Brown.

Conclusions

Diet soda is good for loosing weight compared to non-diet beverages and might even be better than water. There is no good evidence for negative side-effects and experts claim that "a can or two" per day is unlikely to hurt you.

Rogers, P. J., Hogenkamp, P. S., De Graaf, C., Higgs, S., Lluch, A., Ness, A. R., ... & Mela, D. J. (2016). Does low-energy sweetener consumption affect energy intake and body weight? A systematic review, including meta-analyses, of the evidence from human and animal studies. International Journal of Obesity, 40(3), 381-394. https://doi.org/10.1038/ijo.2015.177 Miller, P. E., & Perez, V. (2014). 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), 765-777. https://doi.org/10.3945/ajcn.113.082826 Zeratsky. K. (2018). I drink soda every day. Could this be harmful?. Mayo Clinic. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/diet-soda/faq-20057855 Wikipedia contributors. (2020, May 24). Aspartame controversy. In Wikipedia, The Free Encyclopedia. Retrieved 20:36, June 24, 2020, from https://en.wikipedia.org/w/index.php?title=Aspartame_controversy&oldid=958537828 Mallikarjun, S., & Sieburth, R. M. (2015). Aspartame and risk of cancer: a meta-analytic review. Archives of environmental & occupational health, 70(3), 133-141. https://doi.org/10.1080/19338244.2013.828674 Mishra, A., Ahmed, K., Froghi, S., & Dasgupta, P. (2015). Systematic review of the relationship between artificial sweetener consumption and cancer in humans: analysis of 599,741 participants. International journal of clinical practice, 69(12), 1418-1426. https://doi.org/10.1111/ijcp.12703 Lohner, S., Toews, I., & Meerpohl, J. J. (2017). Health outcomes of non-nutritive sweeteners: analysis of the research landscape. Nutrition journal, 16(1), 55. https://doi.org/10.1186/s12937-017-0278-x Brown, R. J., De Banate, M. A., & Rother, K. I. (2010). Artificial sweeteners: a systematic review of metabolic effects in youth. International Journal of Pediatric Obesity, 5(4), 305-312. https://doi.org/10.3109/17477160903497027