May 27, 2014

Do Diet Drinks Cause Weight Gain? New Study Repeats NOT LIkely

Are you under the impression, though counter intuitive, that downing diet drinks will add pounds to your hips and scale? The root of this notion stems from several large observational studies, which over the last several years, have fed the media’s hunger for headlines to paint diet beverages and low calorie sweeteners as the dieter’s devil.

Yet, when most experts analyze these observational studies as a group their conclusions, such as those from Pereira, conclude this is “an artifact of reverse causality.”(1) In the case of diet beverages this means that the people in these studies at higher risk for weight gain, obesity and/or type 2 diabetes may be more likely to increase their intake of diet beverages to attempt to reduce their disease risks. It doesn’t prove cause and effect. 

Maybe, just maybe, due to one more prospective randomized control study (studies which can test cause and effect) published by Peters, et al., on May 27, 2014, people who wisely count their calories and opt for calorie free vs. calorie and sugar-loaded beverages, will finally be at ease sipping diet beverages.(2)

To the recent study details.

This one year study began with a three month weight loss phase. The remainder of the one year study was the follow up phase. (Weight loss studies repeatedly show people lose most of the weight they’ll lose by about three to six months.) These results only include data from the three month weight loss phase.(2)  

The study, conducted by well-respected weight loss experts at two sites – the University of Colorado Anschutz Health and Wellness Center and Temple University’s Center for Obesity Research and Education in Philadelphia, included both urban and suburban populations. Just over three hundred overweight individuals (Mean BMI: 33, Weight at start: about 208 pounds), who had consumed diet beverages prior to the study, were randomized into two groups.  

Both groups participated in a behavioral weight loss program based on the Colorado Weigh program, which included a calorie reducing eating plan and an exercise program. In addition to this weight control plan one group was instructed to drink 24 ounces a day of any type of diet beverages. (They could have been diet soft drinks, flavored waters, iced tea, etc., with or without caffeine.) The other group was told not to drink diet drinks but instead to drink 24 ounces of water each day. (Coupons for their respective beverages were provided and the researchers had access to coupon redemption data). The use of low calorie sweeteners in other beverages, like coffee and tea was restricted but not the use of them in foods.

Drumroll, please.

Results from the weight loss phase (3 months) of the study showed people in the diet beverage group lost significantly more weight, average of 13 pounds, or 44 percent more than the people in the control group. They lost an average of nine pounds. Sixty-four percent of participants in the study group lost at least five percent of their body weight (the gold standard to achieve some health benefits), compared with only 43 percent of control group participants hitting that five percent goal. And an important added benefit - people in the diet beverage group reported significantly less hunger. 

Regarding health benefits: The diet beverage group, likely by virtue of their greater weight loss and nothing to do with drinking diet beverages, had significant improvements in several cardiovascular disease markers – total cholesterol, LDL- cholesterol and triglycerides. Both groups had a reduction in waist circumference (a marker of metabolic syndrome) and blood pressure. Interestingly, no significant change was reported in fasting glucose results (the study excluded people with type 2 diabetes but not prediabetes).

One year results will be reported in the future. An editorial based on this study by Anton accompanies the paper.(3)

This is not the first time that diet beverages have been shown in a randomized control trial to result in greater weight loss. For one, another six-month randomized control study, referred to as the CHOICE (Choose Healthy Options Consciously Everyday) study, by Tate et al., in 2012, showed similar results. In a population of about 300 people divided into three groups - diet beverage drinking and water consuming and a control group – at the six month mark the diet beverage drinkers experienced a greater likelihood of achieving a five percent weight loss than the water drinkers.(4) A related analysis of dietary consumption patterns in the CHOICE study were published by Piernas et al., 2013 which showed the diet soda drinkers reduced their intake of desserts more than the water drinkers.(5)

What’s the bottom line for calorie conscious scale watchers who want to sip diet beverages to quench their thirst and their sweet tooth? Go for it without concern that diet beverages are going to thwart your efforts as long as you’re consuming them as part of a complete weight management plan. Diet beverages alone won’t melt away your pounds, nor will they mysteriously add pounds to your scale. This is good news. We need all the assists we can get in our continuous battle with weight control.

Now, I’m going to sit back and observe whether the mainstream media reports on this well conducted study or ignores it (as has often been the case) because it doesn’t paint diet beverages and low calorie sweeteners with a halo of horror. Or if they do report it discount its credibility because it was, as is clearly noted in the study, supported by the American Beverage Association (ABA), a Washington, DC-based trade association. 

1. Pereira MA. Diet Beverages and the risk of obesity, diabetes and CVD: A review of the evidence. Nutrition Reviews. 2013;71(7):433-440.
2. Peters JC, et al. The Effects of Water and Non-Nutritive Sweetened Beverages on Weight Loss During a 12-week Weight Loss Treatment Program.  Obesity Journal. 2014;22(6):1415-21.
3. Anton, S: Can Non-Nutritive Sweeteners Enhance Outcomes of Weight Loss Interventions? Obesity Journal. 2014;22(6):1413-14.
4. Tate D: Replacing caloric beverages with water or diet beverages for weight loss in adults: maintresult of the Choose Healthy Options Consciously everyday (CHOICE) randomized control trial. American Journal of Clinical Nutrition. 2012;95:555-563.
5. Piernas, C: Does diet-beverage intake affect dietary consumption patterns? Results from the Choose Healthy Options Consciously Everyday (CHOICE) randomized clinical trial. American Journal of Clinical Nutrition. 2013;97:604-611.

Disclosure: For the sake of transparency results of the Peters, et al., study (2) were shared with me several days prior to publication. Also, I’ve been professionally involved as a consultant with low calorie sweeteners for nearly 25 years and currently am a consultant to McNeil Nutritionals, LLC. I was not compensated for my time to participate on the above noted call or for my time writing this blog.