The Truth About Diet Soda

The authors of Eat This Not That reveal some hard truths about low-calorie sodas.

By Dave Zinczenko and Matt Goulding, Men's Health

Find more: Test Your Nutritional IQ The 8 Worst Breakfasts in America Buy Eat This, Not That! Books

We talk a lot about “watching what we eat,” but if you never gave a thought to what you ate and instead watched only what you drank, you could probably cut 450 calories a day out of your life—that’s nearly a pound of fat trimmed away each week! That's what a study from the University of North Carolina found. Americans today drink about 192 gallons of liquid a year—or about 2 liters a day. To put it into perspective, this is nearly twice as many calories as we did 30 years ago.

When confronted with the growing tide of calories from sweetened beverages, the first response is, “Why not just drink diet soda?” Well, for a few reasons. Eat This, Not That! did some research and found out some hard truths behind the low-calorie (and nutrition-free) beverage. The story isn't as clear-cut as you suspect, and it might make you think twice the next time you're looking for a thirst-quencher.

Hard truth No. 1

Just because diet soda is low in calories doesn't mean it can't lead to weight gain.

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It may have only 5 or fewer calories per serving, but emerging research suggests that consuming sugary-tasting beverages—even if they're artificially sweetened—may lead to a high preference for sweetness overall. That means sweeter (and more caloric) cereal, bread, dessert—everything. Considering there are 15 calories in every teaspoon of sugar, that's not good news if you're watching your weight.

Hard truth No. 2

Guzzling these drinks all day long forces out the healthy beverages you need.

Diet soda is 100 percent nutrition-free—and it's important to remember that all that useless liquid is taking up space that could have gone to more healthy alternatives. On the positive side, it means you won’t be taking in equally non-nutritious, calorie- and sugar-packed options. But it's just as important to actively drink the good stuff as it is to avoid that bad stuff. So one diet soda a day is fine, but if you're downing five or six cans, that means you're limiting your intake of healthful beverages, particularly water and tea, which is high in antioxidants.

Plus, a recent study from Johns Hopkins found that restricting liquid caloric intake is a more effective way to lose weight than restricting calories from food. There’s no better place than by eliminating anything on our list of the 20 unhealthiest drinks in America.

Hard truth No. 3

There remain some concerns over aspartame, the low-calorie chemical used to give diet sodas their flavor.

Aspartame is 180 times sweeter than sugar, and some animal research has linked consumption of high amounts of the sweetener to brain tumors and lymphoma in rodents. The FDA maintains that the sweetener is safe, but reported side effects include dizziness, headaches, diarrhea, memory loss, and mood changes. Check out our guide to the 11 most controversial food additives to see how aspartame stacks up.

The bottom line is this: Diet soda does you no good, and it might just be doing you harm. The best way to hydrate is by drinking low-calorie, high-nutrient fluids—and choosing healthy alternatives, like the ones you'll find in our list of the 16 best drink swaps.

Now that you have a hold on your liquid assets, upgrade the rest of your grocery list by avoiding the 13 Worst "Healthy" Foods in the Supermarket.