Updated 13th March 2024

What happens when you drink too much diet soda?

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Regular soda often contains 10–15 grams of sugar per 100 milliliters of soda. That’s 8–13 g of sugar in a can, or 13–19 sugar cubes.

So, diet soda is often marketed as healthier than regular soda because it contains no added sugar.

In diet soda, sugar is replaced with artificial sweeteners, which provide sweetness but few or no calories. 

But just because something has no calories doesn’t mean it’s healthy.

Below, we'll explore the possible health effects of drinking too much diet soda and the symptoms you might have. These may include gut symptoms, sleep problems, and sugar cravings. 

Health effects

First, we’ll look at the possible health effects of drinking too much diet soda.

Gut health 

Some scientists believe that artificial sweeteners might affect your gut bacteria.

Still, a lot of the research so far was laboratory-based, or it involved animals, not people. And, of course, what happens inside a rat won’t necessarily happen inside a person.

Turning to studies with human participants, not all have found the same effects. 

It’s likely that the health effects of artificial sweeteners vary from person to person, depending on the composition of their microbiome and the type of sweetener.

Some studies in humans have found that consuming artificial sweeteners can lead to changes in the gut microbiome. But others haven’t.

Beyond artificial sweeteners, diet sodas often contain other additives, like coloring and flavoring, which may also affect the gut microbiome

At this point, we don’t know how these changes might influence overall health, but scientists continue to look into the issue.

Weight loss or weight gain?

For people trying to lose weight, there’s some evidence that switching from regular soda to diet soda may help, to some degree.

But other studies have suggested that drinking diet soda may lead to weight gain.

Take one study, which tracked people for over 9 years. It found that those who regularly drank diet soda tended to have higher levels of fat around their middles, compared with people who didn’t. 

But it’s important to keep in mind that weight maintenance is complex, and many factors are involved.

Metabolic health

It’s normal for your blood sugar levels to rise after you eat or drink anything that contains sugar, like regular soda. 

But for some people, these rises are pronounced, and they feel tired and hungry. Over the years, these blood sugar spikes can increase the risk of heart disease.

Because diet soda contains no sugar, you won’t experience large spikes and dips in blood sugar. So, switching to diet soda might seem like a good way to help your metabolic health.

However, some experts believe that drinking diet soda with artificial sweeteners can affect the gut microbiome and negatively impact the blood sugar response.

This, they argue, may increase the risk of developing metabolic syndrome

There’s also evidence linking artificial sweeteners with a greater risk of heart disease and type 2 diabetes.   

Scientists need to do more research into the links between artificial sweeteners, gut bacteria, and metabolic health.

If you’d like to know how your blood sugar levels respond to different foods, ZOE can help

We can also provide information about how your blood fat levels respond to food and analyze the bacteria that live in your gut. To find out more, start by taking our free quiz.

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Blood pressure 

Some studies suggest that diet soda may increase blood pressure. For instance, a meta-analysis from 2015 linked this effect to both regular and diet soda.

However, other studies identified a link between standard soda and higher blood pressure but didn’t see the same relationship with diet soda. So, the jury is out. 

Still, it’s worth noting that many sodas contain caffeine. In fact, some have as much or more than a regular cup of coffee.

And too much caffeine can also increase blood pressure

Many factors influence your blood pressure, including what you eat, how much physical activity you do, and how stressed you are. It’s a complex topic, and we still don’t understand whether diet soda plays a part.


Next, we’ll look at some symptoms you might have if you drink a lot of diet soda.

Gut symptoms 

A lot of diet soda may leave you feeling bloated. This is because sodas tend to be carbonated, and drinking them can lead to gas getting trapped in your system.

Also, if you have a sensitive gut, the caffeine in some diet sodas may cause diarrhea. This is because caffeine activates contractions in your digestive tract, causing food to move through your gut more quickly. 

Plus, some sweeteners in diet sodas — such as sorbitol, mannitol, and xylitol — are known to worsen gut symptoms for some people.

For example, if you have irritable bowel syndrome, eating or drinking a lot of certain sweeteners may cause bloating and diarrhea. 

Sleep problems

Small amounts of caffeine — usually up to 400 mg — don’t cause problems for many people. This amount works out to about 4 cups of regular coffee or 5–6 cups of tea. 

But if you drink a lot of diet soda, the amount of caffeine in your day can easily add up. And too much caffeine has a well-established reputation for affecting sleep quality and quantity. 

Meanwhile, studies in mice have shown that artificial sweeteners can disturb sleep-wake cycles, though researchers haven’t confirmed whether this happens in humans. 


A handful of older studies, including a randomized controlled trial and a cohort study have found that artificial sweeteners may cause headaches in people who are already prone them. 

But other studies have found no effect of artificial sweeteners on headache frequency.

Looking specifically at migraine headaches, a recent review concluded that other dietary factors, such as caffeine, were most likely to be triggers.

Food cravings 

Some studies suggest that artificial sweeteners may play tricks on your brain and increase your food cravings. But scientists still need to do more research. 

In one study, researchers gave participants a 300-ml drink containing either sugar, artificial sweetener, or plain water.

Two hours after participants had the drink containing artificial sweetener, the team found increased activity in the brain region responsible for food cravings and appetite.

And they found that after the artificial sweetener, female participants ate more at the buffet. They didn’t find this in males.

Still, it’s worth noting that all the participants had fasted overnight before the study, so they were probably hungrier than usual.

In another study, researchers gave people standard or diet soda, then showed them pictures of food.

The researchers spotted differences in brain activity between the two groups. After diet soda, there was increased activation of the brain’s reward system and decreased activity in control-related regions.

Although the researchers call for more studies, they conclude that diet soda may lead to reduced inhibition and a greater desire for high-calorie foods.

Alternatives to diet soda

Having diet soda every once in a while is unlikely to harm your overall health. 

But it’s important to remember that diet soda gives you very few nutrients, and there are healthier options. 

If you’re stuck for inspiration, here are some alternatives:

  • Infuse water with fresh fruit, like lemon, lime, melon, or berries.

  • Try fermented drinks, like kombucha.

  • Have a fruit or herbal tea.

  • Go for other teas or coffee, and you might opt for decaf.

  • Try some homemade iced tea.

  • Stick to plain water — it’s cheap, simple, and it does the job.


Diet soda is mostly carbonated water with additives like artificial sweeteners, colors, flavors, and sometimes caffeine. 

In the long run, drinking too much diet soda may affect your gut and metabolic health. Plus, according to some research, it might raise your blood pressure.

Having a lot of diet soda might also worsen any gut symptoms, particularly if you have a sensitive gut. 

Other symptoms might include sleep problems, headaches, and food cravings, though we need more research.

As with most things nutrition-related, moderation is key. There are many other options, like kombucha or fruit teas. 

If you’d like to learn more about how your body responds to different foods and receive ongoing support from trained nutritionists, you can start by taking our free quiz.


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