If you ask me, Diet Coke has always been that girl. I could wax poetic about the carbonated bevvy for paragraphs. But, while I’ll likely never have the type of willpower to turn down a crispy fresh-out-of-the-fridge DC, there’s a dark truth hiding behind its shiny red and silver aluminum: it’s not nearly as “healthy” as its zero-calorie, zero-sugar label suggests.
Despite its undeniable popularity, Diet Coke’s nutritional rap sheet remains a cause for concern. The popular drink has long ignited controversy among researchers, dietitians, and doctors who primarily take issue with its artificial sweetener aspartame. In late 2024, rumors even circulated of a Diet Coke ban, and while it was quickly debunked as just that (a rumor!), it's only revived this decades-long convo.
"Even though Diet Coke doesn’t contain real sugar, its artificial sweeteners can still disrupt metabolism, increase cravings, and lower satiety hormones like GLP-1, making you feel hungrier," nutritionist and founder of @bebalancedco Micaela Riley tells Delish. "It can also negatively impact gut health and insulin sensitivity and even increase the risk of metabolic issues like weight gain and heart disease over time."
Here's what you should consider before reaching for the soda:
Aspartame Might Be Addictive & Increase Cravings
There are a lot of conflicting reports surrounding the risks of aspartame, and that includes whether or not it's addictive. According to WebMD, much like regular sugar, aspartame can trick the brain into releasing hormones like dopamine, which can then lead you to Diet Coke (and other sugary food and drink) cravings more than you otherwise would.
"Diet Coke is chemically designed to reinforce cravings and addiction, making you more likely to consume more diet soda and other sugary products over time," says Riley.
Artificial Sweeteners Can Disrupt Your Metabolism
While, yes, Diet Coke doesn't contain real sugar, it can still mess with your metabolism and even lower satiety hormones like GLP-1, which in turn, causes you to feel hungrier, Riley says. Some studies suggest that artificial sweeteners may influence appetite—you might be avoiding extra calories by drinking the diet version, but it could be triggering you to eat more calories after you've drained the can.
"Aspartame, found in Diet Coke, tricks the brain by stimulating dopamine, reinforcing cravings, and increasing the desire for more sweet foods," she elaborates. "It can also reduce GLP-1, the hormone responsible for satiety, making you feel less full and more prone to overeating."
And yes, she clarifies, GLP-1 is the the same peptide that Ozempic targets to regulate appetite.
It May Cause Insulin Confusion
Some studies have suggested a potential link between artificial sweeteners and insulin sensitivity, which Riley explains as "trying to open a sticky door with the wrong key."
"Normally, insulin is the key that unlocks your cells so sugar (glucose) can get inside and be used for energy," she says. "With insulin resistance, the locks on the doors get rusty and don’t open properly, even though insulin (the key) is there."
As a result, this causes sugar to remain in your bloodstream, leading to high blood sugar. The body may also produce more insulin in response, trying to force that "door" open. Over time, this can lead to hyperinsulinemia (too much insulin in the blood) and consistently elevated blood sugar, which may contribute to weight gain, fatigue, and increased cravings.
To fix this, Riley says, you need to "oil the locks" through lifestyle changes—meaning you can improve insulin sensitivity by strength training, eating balanced meals, increasing fiber, and managing stress "so the doors open properly again," Riley adds.
It May Mess With Your Gut Health
Diet Coke (or more specifically, its artificial sweeteners) can also disrupt your gut health by altering the microbiome.
"Studies show that these sweeteners can increase harmful bacteria while reducing beneficial gut bacteria, leading to an imbalance known as dysbiosis," Riley says. "This imbalance may impair glucose metabolism, contribute to inflammation, and trigger digestive issues such as bloating, gas, and IBS-like symptoms."
It Has Been Linked To An Increased Risk Of Dementia
Research also suggests that Diet Coke and other products with artificial sweeteners might be increasing your risk of dementia. "This is due to aspartame and sucralose disrupting neurotransmitter activity, which can affect brain function," Riley says.
Indeed, a 2017 study on the subject found that individuals who consumed diet sodas daily were three times as likely to suffer from dementia or a stroke compared to those that don't. Another study found similar evidence in 2019 after testing the different effects of sweeteners on behavior and neurotransmitters release in mice.
There Are Cardiovascular Concerns, Too
It's all about the trickle-down effect. Aspartame is linked to a higher risk of metabolic syndrome, which includes elevated blood sugar, insulin resistance, increased abdominal fat, and higher cholesterol levels. These are all major risk factors for heart disease. They also contribute to oxidative stress, which causes inflammation, arterial stiffness, and a general increased risk of hypertension and cardiovascular disease, Riley explains.
A study published in the National Library of Medicine found those who drank diet soda on a daily basis had a 43% higher risk of vascular events than those that did not, and a study published in February 2025 in Cell Metabolism revealed that insulin spikes triggered by aspartame could lead to the buildup of fatty plaques in arteries, potentially increasing the risk of heart attacks and strokes.
It Can Weaken Your Tooth Enamel & Affect The Appearance
Diet Coke also contains phosphoric acid and citric acid, which can weaken your enamel and erode tooth enamel permanently, this study reports. The weakened enamel also stains more easily, so it's affecting your dental health from the inside out. A straw helps to keep your teeth away from the damaging ingredients, though.
It's Linked to Cancer
According to the International Agency for Research on Cancer, the World Health Organization (WHO), the Food and Agriculture Organization (FAO), and Joint Expert Committee on Food Additives say there is "limited evidence" for carcinogenicity in humans as a result of aspartame consumption. The FDA still deems Diet Coke safe as long as daily intake levels are low, WHO reports.
The bottom line: While, sure, in theory everything is fine in moderation, Riley warns that this is hard to define."What does moderation actually mean, and how do we measure it?"
