Diet Soda - Weight Gain - The Truth

November 10, 2020

The relationship between fluid intake and weight

Are you under the impression that if you drink more water you will eat less food?

Diet Soda Weight Gain

Plenty of studies show otherwise. Fluid intake of any kind does not alter how much food is consumed at mealtime; even calorie-loaded beverages have no effect.

However - when you drink a soda, for example, you're adding calories to your total day from the soda itself.

If you drink less sugar-sweetened beverages, you will reduce overall calories for weight loss. Drinking more water may help you accomplish this... all of this has been written about with references in my previous article, Can You Lose Weight by Drinking More Water?

What if you really like your sweet drinks though? What if you don't want to give them up, but want to eliminate the extra calories? Should you switch to diet beverages?

Can you switch to diet soda instead of water to help you lose weight?

At UNC, Tate, et al., set out to answer this question and published their results in 2012. 318 participants were randomized to one of three groups: a group that replaced caloric beverages with diet beverages; a group that replaced caloric beverages with water only; and a group that was simply provided general weight loss information, but not encouraged to change their beverage intake behavior.

At the 3-month point, weight loss was similar in all groups. At the 6-month point, weight loss was still statistically similar, but the diet beverage group did lose a little bit more.

Diet Soda Weight Gain

Interestingly, the diet beverage group had a greater chance of achieving a 5% weight loss, than the two other groups. Furthermore, combined data showed participants were twice as likely to lose 5% of their weight when replacing caloric beverages with either water or diet drinks, when compared to the group that did not receive instructions to replace beverages [1].

Diet Soda Weight Gain

Could this be real? Artificially sweetened beverages resulting in greater weight loss than water?

Peters, et al., noted how plenty of data already exists to validate that eliminating calories from beverages by using artificially sweetened alternatives, is an effective weight loss strategy. They wanted to see if using water would produce greater weight loss than 0-calorie sweetened beverages, and published their results last year.

303 participants were randomized into one of the following two groups:

  1. A group instructed to consume at least 24 fl oz of diet drinks per day, and water consumption was not restricted.
  2. A group that was instructed to consume at least 24 fl oz of water per day, but no diet beverages at all.

Unlike in Tate’s study out of UNC, participants were very closely coached in a comprehensive weight loss program. Their results were still consistent with the previous trial: the average weight loss of the diet beverage group over a 12 week period was about 14 pounds, while the water group lost an average of 10 pounds [2].

Diet Soda Weight Gain

Are you worried about the "dangers" of artificial sweeteners?

In Peter's study, blood profile measurements did not differ significantly between the groups, except the diet beverage group had significantly more favorable effects to their cholesterol outcome [2].

Diet Soda Weight Gain

We have a meta-analysis!

A meta-analysis published in 2014 to the American Journal of Clinical Nutrition examined all the data from randomized controlled trials to see if there’s a true causal relationship between non-calorie sweetener use and weight loss. Their findings confirm that swapping sugar-sweetened beverages out for artificially sweetened alternatives will promote a modestly greater weight loss effect [3].

Diet Soda Weight Gain


It's currently difficult to refute the evidence showing us how diet sodas promote greater weight loss than regular sodas... but the difference is marginal.

If you're naturally a water drinker, should you make the switch to diet drinks in hopes of producing greater weight loss? Of course NOT! You should seek other ways to reduce calories.

If you are struggling to get your caloric intake on par with weight loss, and you're sourcing calories from sugar-sweetened beverages, juices, or milk: switching to diet beverages could help you eliminate those extra calories without compromising on your cravings.

Then again, there are also other things you could do to reduce calories.

Having completed the water/fluid intake series, I have confirmed for myself that trying to manipulate fluid intake in general hopes of accelerating fat loss is simply not worth your effort. I will continue to drink what I want, when I am thirsty and it does not ever need to get more complicated than that.


1. Tate DF, Turner-McGrievy G, Lyons E, Stevens J, Erickson K, Polzien K, Diamond M, Wang X, Popkin B. Replacing caloric beverages with water or diet beverages for weight loss in adults: main results of the Choose Healthy Options Consciously Everyday (CHOICE) randomized clinical trial. Am J Clin Nutr. 2012 Mar;95(3):555-63. doi: 10.3945/ajcn.111.026278. Epub 2012 Feb 1. Erratum in: Am J Clin Nutr. 2013 Dec;98(6):1599. PubMed PMID: 22301929; PubMed Central PMCID: PMC3632875.

2. Peters JC, Wyatt HR, Foster GD, Pan Z, Wojtanowski AC, Vander Veur SS, Herring SJ, Brill C, Hill JO. The effects of water and non-nutritive sweetened beverages on weight loss during a 12-week weight loss treatment program. Obesity (Silver Spring). 2014 Jun;22(6):1415-21. doi: 10.1002/oby.20737. PubMed PMID: 24862170.

3. Miller PE, Perez V. Low-calorie sweeteners and body weight and composition: a meta-analysis of randomized controlled trials and prospective cohort studies. Am J Clin Nutr. 2014 Sep;100(3):765-77. doi: 10.3945/ajcn.113.082826. Epub 2014 Jun 18. PubMed PMID: 24944060; PubMed Central PMCID: PMC4135487.

October 7, 2021