Is Diet Soda Keto Friendly? All You Need to Know About This Carbonated Drink on a Keto Diet

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Is Diet Soda Keto Friendly? All You Need to Know About This Carbonated Drink on a Keto Diet

Diet soft drinks are low-carb and low-calorie - but are they keto-friendly? Learn how diet sodas sabotage your health gains & what to drink instead.

Diet Soda Keto

It’s no secret that soda has been the cause of some serious health concerns for decades. Not only is it packed with sugar, but the other artificial ingredients found in this carbonated drink make it hard to imagine it has any benefits.

We all have that one relative who goes to town on packs of Coke Zero on a regular basis. But what is this doing to their bodies?

While some people resort to diet soda for the lower carb count, it may actually be worse than regular soda or fruit juice.

Sure, it has no calories, no carbs, no sugar, and the same sweet taste, but that’s only because it’s packed with artificial, harmful ingredients instead.

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Almost every sweetened beverage on the market today has some sort of “diet” or “light” option. But are they really a lighter, or keto option? And more importantly, how do they actually impact your health?

What is Diet Soda?

Let’s take a look at one of the more popular brands today — Diet Coke. One serving of Diet Coke contains:

  • 0 calories
  • 0 grams of fat
  • 0 grams of total and net carbs
  • 0 grams of protein
  • 40 mg of sodium

As you can see, diet soda doesn’t give you much nutritional value. With its basic mixture of carbonated water, artificial sweeteners, colors and other different additives, there’s no significant nutrition to be found in this beverage whatsoever.

But even though the ingredients are nutritionally void, they do affect your health in multiple ways.  For one of the top name brands out there today, the ingredients include:

  • Carbonated water
  • Caramel coloring
  • Aspartame
  • Phosphoric acid
  • Potassium citrate
  • Natural flavors
  • Citric acid
  • Caffeine

Here’s what they are and what they do:

The “caramel coloring” is made by heating up corn or cane sugar to reach the desired caramel color.

Aspartame is a low-calorie sweetener. Once consumed, aspartame almost immediately breaks down into three chemical compounds: phenylalanine, aspartic acid and methanol. The first two are amino acids.

While phenylalanine is recognized as being safe in whole food products, it can be toxic in large doses — which is the case with diet soda. Because phenylalanine is chemically bound in aspartame, it can be absorbed immediately.

Unfortunately, the third chemical compound in aspartame, methanol, is easily converted to “free methanol” in hot temperatures. Once in this state, free methanol converts to formaldehyde.

Formaldehyde is a carcinogen and has the ability to cross the blood-brain barrier (a filter of capillaries that carry blood to the brain and spinal cord).

It’s not surprising then that aspartame has been linked to multiple health concerns, including:

  • Depression
  • Anxiety
  • Short-term memory loss
  • Multiple sclerosis
  • Fibromyalgia
  • Weight gain
  • Fatigue
  • Epilepsy
  • Alzheimer’s disease
  • Diabetes
  • Arthritis
  • ADHD
  • Parkinson’s disease[*].


Drinking diet Coke or Pepsi is worse than you thought.

So, while this harmful drink may contain zero calories, the question remains — is diet soda keto friendly?

Does Diet Soda Fit Into a Ketogenic Diet?

Sure, diet soda may be zero calorie and zero carb, but the artificial ingredients found in it don’t support the health goals of the keto diet.

The ketogenic diet is a complete metabolic transformation that puts your body in fat-burning mode instead of glucose-burning mode so you can enjoy more energy, have a better mood, lose weight, lose fat, and attain more focus.

However, drinking low carb beverages filled with artificial ingredients may do the opposite of what you want to accomplish with a high-fat diet.

Even if diet soda keeps your daily carb intake low, doesn’t raise your blood sugar, and doesn’t affect your ketone levels, remember that ketosis in itself isn’t healthy — and there’s no point in getting into it if you’re not doing healthily.

Diet soda has been shown to damage many of the functions a ketogenic diet would otherwise improve.

It can prevent weight loss, harm your metabolism, and contribute to conditions like:

  • Depression
  • Kidney damage
  • Diabetes
  • Cardiovascular disease
  • Cavities
  • Obesity

Some of these problems actually seem to be worse in people who consume diet soda instead of regular soda. Pretty crazy, huh?

In fact, one study showed the risk for depression increased for individuals drinking diet soda instead of regular soda. Drinking more than four cans a day of diet soda was linked to a 30% higher risk of depression[*].

That’s not the only surprising statistic.

Individuals who consumed diet soda over a long period of time also showed a 30% decrease in proper kidney function. This was a study conducted at Harvard over the course of a 20 year period[*].

Cardiovascular disease is one of the top killers in the United States today, and diet soda may be a silent contributor. In a 10-year study that involved 2000 adults, individuals consuming diet soda on a daily basis were more likely to experience a stroke or heart attack[*].

Artificial sweeteners also affect your metabolism. When you eat them, your body detects a sweet taste and expects a corresponding increase in blood sugar and insulin levels, but because it’s a low carb sweetener, this doesn’t happen. Over a long period of time, these mixed signals can trigger the metabolic syndrome and type II diabetes[*].

This clearly shows diet soda is not only unhealthy but even worse than your regular sugar-filled soda.

So Is Diet Soda Keto Friendly?

Diet soda is particularly damaging to your health. It doesn’t matter that it’s carb-free and calorie-free, you should never drink diet soda if you want to enjoy the multiple health benefits of a ketogenic diet.

There are far better keto drinks that let you stay in ketosis and support a healthy ketogenic diet, such as sparkling water.

Diet coke is not suitable for a healthy ketogenic diet.


10 thoughts on “Is Diet Soda Keto Friendly? All You Need to Know About This Carbonated Drink on a Keto Diet

  1. This should have been a yes or no question? Will I break my Intermittent fast or go out of ketosis with a diet soda? Yes or No. The whole article was about the health aspect of the drink and did little to answer the actual question.

    1. Hi Andrew, it should not break your fast nor kick you out of keto however the ingredients are nutritionally void and may affect your health in multiple ways.

  2. Yeah Andrew nailed it. This article was more of a 9th grade persuasive essay for reasons not to drink diet soda. No it won’t break ketosis but it’s not good for you. Bam!

  3. Can i get a link to those study`s? Your facts seems a bit shady… And one other thing, what about cola zero? it`s made with stevia

    1. Hi Laila, you can find the associated studies by clicking the asterisk[*]. Also, you may want to refrain from drinking cola since it contains artificial ingredients even though it has zero carbs.

  4. What if we can’t and won’t o diet soda? I hate diet absolutely hate it. Will be just not lose as much weight if I limit it to one can?

    1. I think if you can’t help yourself, a 100ml will suffice. A can of soda is a keto breaker for me but I occasionally “sip” one or two.

  5. Go read the Coke Zero ingredients. It reads contains Aspartaine! No where does it read Stevia! Are there any real cola diet drinks that have Stevia or another better sweetener out there?

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