Why Is Diet Soda Bad for You?

Last Update: May 12, 2023

Healthy eating involves making good choices each and every day—from food purchases to meal prep, ingredient subs to diligent recipe research. With so much time devoted to the process, it can be disheartening to discover that certain products that have promised positive benefits are really some of the unhealthiest options of all.

One of the biggest culprits is diet soda. With attention-grabbing promises like “zero-calorie” and “sugar-free,” diet sodas certainly speak the language of healthy foods. But take a look closer and you’ll notice the meaning of those words becomes less genuine.

Diet sodas aren’t the health-conscious, dream-come-true beverages they claim to be (a San Antonio Heart Study found that drinking it could actually increase weight gain by stimulating appetite). Even worse, they often trade in their lack of calories and sugar for chemicals that can wreak havoc on the body.

The ABCs of diet soda

So what’s so bad about diet soda? There isn’t just one problem. In looking at the packaging, an alphabet of questionable ingredients and chemicals start to jump out, the most common being:

  • Aspartame
  • BPA (or bisphenol A)
  • Caramel color

The ramifications of each of these ingredients have long been studied, with each found to cause or contribute to serious health concerns.

The truth about aspartame

The most popular member of this clique is aspartame, which has been targeted as an ingredient to avoid. It’s made when two amino acids, aspartic acid and phenylalanine, are joined to make a low-calorie alternative to sugar.

It has been used in many diet sodas, including all the big name brands (though here’s a list with manufacturers that don’t use it). Since it’s roughly 200 times sweeter than sugar, aspartame isn’t needed in high concentrations to sweeten foods and beverages, which results in fewer calories.

So what’s the tradeoff? While the effects of aspartame on the body are still hotly debated, none of them seem good.

One of the biggest points of contention is whether or not the additive causes cancer. Though a number of studies have all but come out and said so, the American Cancer Society states that said studies have not consistently proven aspartame to be a carcinogen.

But, even ignoring potential cancer risk as a huge red flag, doctors have noted other possible negative side effects of ingesting aspartame, which can include:

  • Dizziness
  • Memory loss
  • Diarrhea
  • Migraines
  • Regular headaches
  • Mood swings

So, even though long-term effects of aspartame are still being tested, there’s still a fair amount of evidence showing that it does more harm than good.

The truth about BPA

Most people have been exposed to BPA in their lifetimes. BPA, or bisphenol A, is a chemical commonly used in making plastics, specifically polycarbonate plastics and epoxy resins, which are used in a slew of food packaging products. That includes reusable water bottles, soup cans, and—you guessed it—soda cans and bottles.

While BPA is not an ingredient in diet soda itself, the packaging used means soda can have a lot of exposure to BPA, giving the harmful chemical plenty of opportunity to leech into the drink.

In a newsletter from the Center for Science in the Public Interest (CSPI), the organization shared results from a study that looked into the side effects of BPA on lab animals. Some of their conclusions were that it was linked to:

  • Increased rates of breast cancer and prostate cancer
  • Increased risk for obesity
  • Higher rates of attention deficit hyperactivity disorder (ADHD)
  • Early onset of puberty

The newsletter goes on to say that pregnant women, nursing mothers, and children are especially susceptible to the effects of BPA. To help avoid it, CSPI encouraged pregnant and nursing women (and parents in general) to store food in glass jars, avoid microwaving food in any plastic containers, and to keep plastic containers out of the dishwasher since the detergent and heat could break down the materials and release BPA.

The truth about caramel color

The truth is: There’s nothing delicious or appetizing about caramel color. While it may sound familiar, it actually has nothing in common with the sweet candy that shares its name. Caramel color is in fact artificial food coloring—and one that may be carcinogenic since it involves heating sugar together with ammonium compounds.

According to the Food and Drug Administration (FDA), inside caramel color is a chemical called 4-methylimidazole (4-MeI), which may also be a carcinogen. Beverages like diet colas with more than 29 micrograms of 4-Mel are required to have health-warning labels, at least under California law, but not all products do. In a Consumer Reports study, researchers found more than 29 micrograms of 4-Mel in 12-ounce samples of Pepsi and Malta Goya.

Caramel color is also on CSPI’s list of ingredients to avoid, which in essence should be easy to do since it’s just food coloring, used to darken baked goods, gravies, sodas, and beer to make them look more appealing. Though, many mass market products still include it.

Ways to kick the habit

Giving up diet soda is a good step to take for your overall health, but if your daily drink of choice is diet cola, you’ll want to take some extra steps to do so the right way. That’s because sometimes going cold turkey can suddenly cause some unwanted symptoms, including:

  • Fatigue
  • Headache
  • Anxiety
  • Difficulty concentrating
  • Increased irritability

These are the symptoms of caffeine withdrawal. Aside from the artificial sweeteners and fake colors, diet soda can also be a major source of caffeine—a 12-ounce can of diet cola can contain up to 47 milligrams. While that figure is not terrible in moderation, if you start drinking from “big gulp” containers multiple times per day, it can add up quickly.

To avoid withdrawal symptoms, here are some tips for how to safely eliminate diet soda:

  • Wean off it gradually. Instead of drinking several cans or bottles per day, slowing start reducing the overall amount.
  • Mix the soda with water. Try mixing in a little water if the need for diet soda is still too strong to ignore. Not only will it dilute the drink and offer a bit more hydration, but the taste will be less palatable, which over time will likely turn off the craving for it.
  • Find alternatives. There are plenty of healthier drink options to enjoy during the day. Water is obvious, or even coconut water, but if you prefer something similar to soda, consider some of the below options.

Alternatives to diet soda

Stock your fridge with some of these tasty chilled options, and over time, you’ll probably be more compelled to make them your drink of choice.

Unsweetened or lightly-sweetened tea or coffee

Can’t get away from caffeine just yet? Try switching to tea or coffee. They’ll still offer that boost of caffeine, but without the artificial ingredients. Follow these steps to make some at-home cold brew or a flavorful white tea granita touched with a bit of honey. (A little lemon and agave can also do the trick to provide a boost of flavor.)


Kombucha is a nutritious fermented beverage made from tea, yeast, bacteria, and sugar. Tart and bubbly, it’s a delicious way to cast away diet soda’s spell. It’s sold by the bottle or the bag, and for DIY types, there’s an all-you-need kit to make it at home.

Naturally flavored seltzer water

Making a pseudo-soda at home could also help break the chains of diet soda. Instead of buying flavored waters, which still contain sugar and other artificial sweeteners, try concocting some delicious recipes straight from the fridge.

Start with plain bottled seltzer water, and then add slices of seasonal fruits or vegetables. That’s it! Whether it’s limes, lemons, oranges, strawberries, blueberries, cucumber, rosemary, or mint, these flavorful options will add natural sweetness and taste to plain water. All the fizzy carbonation will still be there, just without the harsh chemicals found in soda.

Guayusa drinks

Guayusa is an Ecuadorian plant known for its ability to improve energy levels and mood and provide natural energy without the sugar crash.

More healthy drinks to make at home

Want to get even more creative? Here are a few recipes to consider when looking for another crisp, fresh, and mouth-watering alternative.

Peach-Thyme Spa Water

Fresh peach, bright thyme, and sparkling mineral water are what make this refreshing combination really pop. Light and fizzy, this smooth spritzer is a delightful way to replace heavy diet soda.

Ginger-Lemongrass Limeade

In this recipe, limes keep the citrus bite of lemonade without the sourness. Mix the fruit juice with fresh ginger, honey, and mint leaves for a Thai-style beverage that has just the right balance of familiar and surprising flavors.

Orange-Thyme Switchel

Looking for something naturally sweet? This lively drink can take care of that craving. With natural flavor enhancers like apple cider vinegar, maple syrup, and orange juice, this tangy brew will wake up the taste buds—and can also help to settle a stomachache.

Grapefruit-Rhubarb Spritzer

This drink is as delicious as it is unique. Not only is it a more advanced take on classic grapefruit juice, but the added rhubarb and ginger help give it a big burst of flavors, not to mention vitamin C and antioxidants.

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