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Can Diet Pop Interfere With Weight Loss?



sharma-obesity-tap-water1According to conventional wisdom, beverages with artificial sweeteners should be weight neutral, given that they do not contain calories. However, whether this is true or not remains controversial. Besides the epidemiological evidence suggesting that the consumption of artificially sweetened beverages may be associated with higher body weights, there are also a range of physiological studies suggesting that artificial sweeteners can induce metabolic changes (including changes in taste preferences) that may promote weight gain.

Now, a study by Ameneh Madjd and colleagues from the University of Nottingham, UK, and the Tehran University of Medical Sciences, Iran (where the study was conducted) published in the American Journal of Clinical Nutrition, suggests that replacing ‘diet beverages’ (DBs) with water may not only result in greater weight loss but may also have greater benefits in terms of glucose metabolism.

The study was conduced in 89 women with overweight or obesity who usually consumed DBs in their diet.

Participants were randomized to either replace their DBs with water or continue drinking DBs 5 times/wk after their lunch for 24 wk (DB group) while on a 24-week weight-loss program.

71% of participants completed the trial (32 in the DB group, 30 in the water group).

Over the 24 weeks, the water group lost about 1.2 Kg more than the DB group (mean weight loss of both groups was about 8 Kg).

Improvements in fasting insulin levels, HOMA index and 2-hr post-prandial glucose also tended to be greater in the water than in the DB group.

Thus, the authors conclude that replacement of DBs with water after the main meal may lead to greater weight reduction and more favourable metabolic benefits during a weight-loss program.

As for the possible mechanisms that would account for these findings, the authors speculate based largely on self-reported changes in food intake that the water-drinking group may have been more compliant to the recommended diet and may have marginally reduced their carb intake.  There is also the possibility that drinking water (rather than DBs) may support weight loss through other mechanisms.

Overall, I am not sure what to really make of this study. Clearly, being able to replace DBs with water may be beneficial. On the other hand, the more common problem in my practice is dealing with patients who consume larger amounts of sugar-sweetened beverages (SSBs rather than DBs) and I would imagine that if a shift to water is too drastic, DBs may at least be substantially better than continuing on with SSBs for these patients.

@DrSharma
Edmonton, AB

10 Comments

  1. I think you mean the water group lost more.

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  2. I would be interested to know what, if any, relation consumption of Diet Beverages has on Gut Bugs and the ability / inability to loose weight.

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  3. I think you may have a typo above. In the sentence beginning “Over the 24 weeks” didn’t you mean to use the word “more,” not “less”?

    FWIW, during my weight loss and the four first years of maintenance, I drank DBs like a madwoman. Sometimes six cans a day. I’m now a water person, just because I’m suspicious of chemicals.

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  4. Is there an error in your summary?

    “Over the 24 weeks, the water group lost about 1.2 Kg less than the DB group …”

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  5. I agree diet beverages are still better than sugar filled beverages. There is merit to food selection difference with water, at least for me. I would not eat much if I couldn’t combine the food with a Diet Coke/Peps, etc. Pizza comes to mind, now I’m hungry

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  6. I’m thinking with all these numerous studies lately on people consuming diet drinks being associated with co-morbidities in the Metabolic Syndrome while those taking water being NOT or LESS associated with these chronic non-infectious diseases, is it possible that its more of a cause rather than an effect? Meaning people who need to lose weight have a tendency to drink Diet Beverages instead of Sugar-Sweetened Beverages while those who don’t need to lose weight (including those that are Metabolically Healthy Obese) usually take water because they have a disciplined diet from the start which is why they are healthy? I mean which came first, their intake of DB whose effect are Metabolic Diseases or because they already have a Metabolic disease, it causes them to want sugar but since they know its bad for them, they just take DB’s to still have that sweet craving satisfied?

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    • I agree with the comment from Dr Torres. Most of the evidence which shows a correlational relation, somehow becomes cause-effect after publication and before the media report. Is there really a relation? Who knows. There are theories by absolutely no support for a definative causal relation. As Dr. Torres says, ovrweight in general may be more likely to consume diet beverages as a strategy to manage weight. Normal weight individuals may not drink pop at all or drink regular pop because they are not concerned about weight gain.

      I havent seen the full publication of this study as of yet but I doubt they did any food or calorie intake analysis. To truly test for an effect of diet pop on weight gain, you would have to ensure that the caloric intake of the study groups was the same. They likely would have found that the caloric intake of the diet pop group was higher. In this case, the results would show that diet pop consumption would be related to behavioural changes in food intake and not to weight gain directly. So, more study could look into how diet pop consumption affects ones diet in general. Focus would be taken away from a direct effect of diet pop on metabolism. It may have been that the water was replacing other caloric beverages in the water group.

      As well, the test groups were divided into a water or diet pop group and 1 cup of either beverage was had 5 days a week after lunch. Were the participants even drinking a beverage after lunch before the study started or was this a lifestyle change imposed by the study? It really doesnt seem like a popular or convenient time to be drinking pop and imposed changes obviously have effects that wouldnt have occurred otherwise.

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