Examine publishes rigorous, unbiased analysis of the latest and most important nutrition and supplementation studies each month, available to all Examine Members. Click here to learn more or log in.

In this article

Can diet soda ruin your diet?

Evidence is still quite mixed when it comes to diet soda effects on weight loss (or gain). Observational evidence often contradicts with trial evidence. This study adds to the body of evidence, specifically on those with type 2 diabetes.

Study under review: Beneficial effects of replacing diet beverages with water on type 2 diabetic obese women following a hypo-energetic diet: A randomized, 24-week clinical trial.


When it comes to weight loss, eliminating sugar-sweetened beverages (SSBs) is low-hanging fruit. However, research isn’t clear on the impact of replacing these with diet beverages flavored with artificial sweeteners. As shown in Figure 1, these sweeteners interact with taste buds to produce a sweet sensation, yet they don’t provide substantial energy to the body like sugar would.

Figure 1: Sweetener and taste bud interactions

Adapted from: Fernstrom et al. J Nutr. 2012 Jun.

Artificial sweeteners, like aspartame, saccharin, and sucralose, have been the subject of nutrition debates for years. Trials that examine the effect of diet beverages versus water on weight regulation show mixed results, with at least one showing a benefit[1] for diet beverages, while another shows no difference[2]. Observational studies on artificial sweeteners, also called non-nutritive sweeteners or NNS, frequently show associations between NNS and obesity or diabetes[3].

So, other researchers have tried to determine why artificial sweeteners aren’t a surefire trick for easier weight loss. Some theorize that artificial sweeteners act on the brain and increase our desire[4] for sweeter foods. Others theorize that dieters reward themselves with more calorie-dense treats when they choose diet sodas rather than sugary treats. Recently, scientists have questioned whether artificial sweeteners affect the microbiome[5] and prevent weight loss by affecting gut bacteria.

But the varied scientific outcomes still leave questions unanswered. What’s the bottom line ... are diet drinks a poor choice for weight loss? And if they are, why? Like everything else, it may depend on the context.

In the study under review, researchers wanted to examine how diet soda may differentially affect the weight loss of adult women with diabetes. Researchers assigned one group of women to a diet that included diet soda and a second group that did not. Weight loss, metabolic markers, and other surrogate health markers were examined.

In a previous study[6], researchers found a slight beneficial effect of replacing diet beverages with water in obese women without diabetes on a low calorie diet plan. In the current study, researchers wanted to examine whether they would see the same effects in women with obesity and type II diabetes.

Artificial sweeteners, and diet beverages in general, remain controversial in the nutrition community, despite the low calorie count. Observational studies show correlations between diet soda intake, weight gain, and metabolic syndrome that could prevent health professionals from recommending them. A previous study by the same authors found that obese women who replaced diet beverages with water had improved weight loss. The current study examines whether the addition of diet soda or water has an effect on women with diabetes enrolled in a weight loss study.

Who and what were studied?

Become an Examine Member to read the full article.

Becoming an Examine Member will keep you on the cutting edge of health research with access to in-depth analyses such as this article.

You also unlock a big picture view of 400+ supplements and 600+ health topics, as well as actionable study summaries delivered to you every month across 25 health categories.

Stop wasting time and energy — we make it easy for you to stay on top of nutrition research.

Try free for two weeks

Already a member? Please login to read this article.

What were the findings?

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

What does the study really tell us?

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

The big picture

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

Frequently Asked Questions

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

What do I need to know?

Become an Examine Member to unlock this article.

Free 2-week trial »

Already a member? Please login to read this article.

Other Articles in Issue #26 (December 2016)

  • Gelatin + vitamin C + exercise = joint benefits?
    Exercise can help remodel soft tissue, including the collagen in joint tissue. Researchers already knew that vitamin C and gelatin are involved in collagen formation, and here they are tested along with exercise in a randomized trial.
  • What happens to diets when you control food quality?
    Dieters often control their intake of either carbs or fat. But when dieting, the overall quality of food you eat can also change. Do low-fat and low-carb diet effects differ, even if you control for food quality?
  • Interview: Dr. Taylor Wallace, PhD
    Dr. Wallace has done research in a variety of areas, including anthocyanins in plants. Here, we ask him about topics ranging from food additives to supplement side effects.
  • Cut out FODMAPs, cut out IBS symptoms?
    If you have IBS, you know that physicians often lack well-supported dietary recommendations, so new research can be extremely valuable. This study is the first meta-analysis on the low-FODMAP strategy for curbing IBS symptoms
  • Can probiotics help with Alzheimer’s?
    With an aging population, more and more people know someone with Alzheimer’s. As a disease of the brain, symptoms could be helped by supporting an organ that plays directly into brain health: the gut.
  • Curcumin for a clear nose
    There are two types of people in the world: those who get seasonal allergies, and those who don’t. If you sneeze and wheeze, this trial on curcumin for allergic rhinitis provides must-read information.
  • Interview: Grant Tinsley, PhD
    Remember that neat intermittent fasting study in the previous issue of NERD? We were lucky enough to interview one of the study authors, Grant Tinsley.