Does Diet Soda Cause Weight Gain?

photo: loldig

By Crabby McSlacker

One of the most perplexing research findings in recent years, at least to me, is that drinking diet soda leads to weight gain.

Which totally sounds like crazy-talk! Seriously, drinking no-calorie drinks instead of beverages filled with sugar causes you to add pounds, not lose them?

Well, a couple of studies have come out that might be a bit more encouraging to folks who choose diet sodas in an effort to lose weight, especially those who are not obese and are looking to avoid becoming so.

But, does that mean you should run immediately to Costco and buy 437 cases of your favorite sugar-free beverage?

First off, before we get all sciencey, a couple of DISCLAIMERS:

So yeah, I sometimes drink diet soda. Not a lot, maybe 2-3 sodas a month. Plus I have a lot of stevia in my drinks and there's sucralose and erythritol in some of my Quest bars and other fake foods I eat. And I sometimes drink, of all bizarre concoctions, sucralose-spiked Diet Cran-Cherry juice mixed with some carb-killing apple cider vinegar.

And I'd consume even more of all that stuff if I were convinced it was 100% safe to ingest vast quantities over the long haul.

But this post isn't about whether artificial sweeteners are dangerous or not, which is a contentious and confusing issue that I don't think is as straightforward as either the pro-sweetener or anti-sweetener camps make out.  This post is just addressing the curious question of whether drinking diet drinks prevents or encourages weight gain.

However, my own personal desire to drink this stuff means I'm going to be looking a lot harder to find research that says diet soda ain't so bad than someone who cheerfully eschews artificially flavored anything and is perfectly content with their boring old water. I will still drink my boring old water, but I'm NOT content with it.

OK, now that we've got those disclaimers out of the way...

The Link Between Obesity and Diet Sodas

So I've always been pretty unimpressed with research linking diet sodas to obesity, based solely on the fact that obese people drink more diet sodas than slim ones.

That's like noticing old people use canes and walkers way more than young people do, and then concluding that using canes and walkers will make you old.

It makes more sense to me to think that fatter people are going to be more motivated to drink lousier tasting sugar-free drinks to save calories! As opposed to people who can drink the real stuff because they don't need to lose weight in the first place.

I may be missing something, but it seems to me unless you can take a huge bunch of people and randomly make half of them drink diet soda for at least a decade or so, and absolutely prohibit other folks from drinking it and then see what happens to everyone's weight, you're not going to be able to tease out the impact of self-selection on long-term weight gain. Otherwise, the tendency of people gain weight more easily to shift to low calorie drinks is gonna f--ck with your results.

So phooey on those studies. What else we got?

Artificial Sweeteners and Fat Rodents

Oops.

Well, a number of years ago there were other signs of trouble which I decided to ignore: Rodent studies started showing that the something funny was going on with weight and diet foods.  Like in this  rat study, where rats who ate artificially sweetened yogurt gained more weight than those whose yogurt was sweetened with glucose.

(And btw, who knew rodents ate yogurt in the first place?  I'm imagining Dannon and Yoplait should jump on that real quick with rat-friendly yogurt marketing campaigns! Let's not let any potential yogurt consumers go untargeted, right?)

Potential Dollars Left on the Table, Yogurt People.

photo: Jess Hamilton

Anyway, the researchers theorized that why this happened was:

Sweet foods provide a "salient orosensory stimulus" that strongly predicts someone is about to take in a lot of calories. Ingestive and digestive reflexes gear up for that intake but when false sweetness isn't followed by lots of calories, the system gets confused.

And sheesh, talk about confused! I sure was.

I figured if ingesting artificial sweeteners can defy the laws of physics and create energy and mass out of nothing, maybe we could start converting power plants into sugar free sweetener factories? And fill up our cars with Coke Zero and start powering our homes with little packets of Equal and solve the freakin' world energy crisis and prevent global warming! Because who needs to pollute the earth burning fossil fuels when we can just power everything with magical energy-creating fake sweeteners?

But, turns out that what seems to be happening is that some consumers of diet sodas are over-compensating for their beverage by eating more food.  This, to me, is a less alarming finding that that diet drinks are somehow manufacturing pounds out of thin air.

Which Diet Soda Drinkers Seem to Be Overcompensating By Eating More Junky Crap?

There was an interesting study on diet drink consumption and calorie intake earlier this year in which researchers looked what 24,000 people consumed over 24 hours.   Here's what they found:

• Healthy-weight adults who drank diet sodas consumed less food and significantly fewer total calories per day than did healthy-weight adults who drank sugared drinks.
• However, overweight and obese adults who drank diet beverages did not consume fewer calories as those who drank sugary beverages; they made up for the sugary sodas by eating more calories from food. Overweight diet beverage drinkers ate 88 more calories a day; obese adults averaged 194 extra.
• Specifically, obese diet beverage drinkers ate significantly more snacks; 131 calories per day in salty snacks and 243 in sweet snacks, compared to 107 and 213 for obese adults who drank sugared drinks.

So, if there is some over-compensation going on, at least in this study, it seems to be the heavier folks who are doing it.

New Study: Diet Sodas May Help Dieters Lose More Weight

And some actual good news for diet soda fans:

A recent 12 week diet soda study found that dieters who were allowed to drink diet soda lost quite a bit more weight than those who had to drink just water. The diet soda drinkers lost an average of 13 pounds, 44 percent more than the control group, who lost nine pounds.

While the study was industry-sponsored, it doesn't make it totally bogus, and it was peer-reviewed.

However, the quote from James Hill at the Anschutz center in the  diet soda study press release is pretty hilarious:

"A groundbreaking new study to be published in the June issue of Obesity, the journal of The Obesity Society, confirms definitively that drinking diet beverages helps people lose weight.” 

Gosh, let's look at what happened during a 12 week diet... and then let's generalize that to a lifetime of weight management, and say we've definitively confirmed that diet drinks help with weight loss?  Because everyone knows once you've gone on a diet for a few months, problem solved!

(Though to be fair, the press release cites two earlier studies showing a similar advantage to diet beverage drinkers after 6 months. But still, 6 months is hardly "long term" in the weight management game.)

So what do you guys think of all this?  Any other diet beverage drinkers out there willing to step forward or are you all virtuous water drinkers?

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