Is Diet Soda Bad For You? [Spoiler: Yes] - Old School Labs
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Home » OSL Blog » Is Diet Soda Bad for You? Here’s What It Does to Your Health

Is Diet Soda Bad for You? Here’s What It Does to Your Health

August 14, 2019

Key Takeaways

  1. The current research on diet soda is conflicting. Some studies show that it contributes to diabetes, obesity, and weight gain, while others indicate the opposite.
  2. Although diet soda is sugar-free, it contains artificial sweeteners and chemicals that may affect your health in the long run.
  3. In clinical trials, artificially sweetened beverages have been shown to increase diabetes risk by up to 67 percent and coronary heart disease risk by 30 percent.
  4. The non-caloric sweeteners in diet soda may affect insulin response and glucose metabolism.
  5. An occasional glass of diet soda is unlikely to cause weight gain. Stay on the safe side and enjoy this beverage in moderation.

Diet soda may seem like a healthy choice for those trying to shed stubborn fat, but in fact, the opposite is true. According to a cohort study published in the Journal of the American Geriatrics Society, this beverage promotes abdominal weight gain and increases waist circumference. 

Research shows that diet soda contributes to diabetes.

A growing body of research shows that diet soda may contribute to heart disease, stroke, diabetes, obesity and everything in between. It might even put you at risk for depression. 

So, is diet soda bad for you? Although this drink has no carbs and sugars, it can still cause a lot of harm. After all, it’s loaded with artificial sweeteners, synthetic flavors, preservatives, and other chemicals. 

Most studies are conflicting, though. For every study that warns against the dangers of diet soda, there is another study supporting its potential health benefits. 

Let’s take a closer look at America’s favorite beverage and its impact on your health and fitness. 

What’s Really in Diet Soda? 

Diet soda is a popular choice among dieters and athletes alike. We drink it to avoid the extra sugars and empty calories from regular soda, sports drinks, fruit juices, and other similar beverages. 

But do the benefits of cutting out calories outweigh the risks of consuming aspartame, caramel color, and phosphoric acid? 

According to scientists, the answer is No

Most diet drinks have a similar composition. In general, they contain carbonated water, artificial sweeteners, citric acid, concentrated fruit juice, potassium citrate, potassium benzoate, artificial food dyes, and caffeine. 

Depending on the brand, the ingredients list may also include:

  • Aspartame
  • Saccharin
  • Sucralose
  • Stevia
  • Natural and artificial flavors
  • Caramel color
  • Yellow 5 and Yellow 6
  • Red 40
  • Phosphoric acid
  • Disodium EDTA
  • Acesulfame potassium
  • Guar gum
  • Acacia gum
  • Sodium phosphate
  • Sucrose acetate isobutyrate
  • Brominated vegetable oil
  • Modified food starch 
  • Malic acid
  • Sodium citrate
  • Polyethylene glycol

Some ingredients are harmless, while others may contribute to the onset of cancer, insulin resistance, and hormonal disorders. Here’s a quick breakdown of their potential side effects

1. Yellow 5 & Yellow 6

These artificial food dyes are widely used in soft drinks, diet drinks, cereals, chips, candy and sauces. Along with Red 40, they make up 90% of all food dyes

yellow 5 and 6
Yellow 5 & 6 are widely used artificial food dies .

All three contain benzidene, a known carcinogen. 

food dyes
Yellow 5 & 6 contain a carcinogen, benzidene.

2. Caramel Color 

Caramel color, a popular ingredient in diet coke and other beverages, may contain 4-methylimidazole (4-MeI). This compound has been classified as a potential carcinogen

Caramel Color
Caramel color i a well known ingredient in diet sodas and beverages.

Most soda brands only contain small amounts of 4-MeI, so they’re unlikely to cause adverse effects. The problem is that most of us drink a lot more than the recommended serving size. Some folks consume one or more bottles of diet coke daily! 

caramel color
Caramel color contain a potential carcinogen.

In animal studies, caramel color has been linked to higher rates of leukemia and cancers of the liver, lung, and thyroid. Sure, their findings may not apply to humans, but is it really worth the risk?

3. Sucralose 

Most diet soda brands contain sucralose, a non-nutritive sweetener (NNS). Acesulfame potassium, saccharin, monk fruit, neotame, and aspartame fall into the same category. 

Sucralose, a non-nutritive sweetener, is a popular ingredient in diet sodas.

Contrary to what you may have heard, artificial sweeteners don’t cause cancer. This doesn’t mean they’re safe, though. 

sugar in blood
Sucralose affects insulin response and glycemic control in obese individuals.

A 2013 study featured in the journal Diabetes Care has found that sucralose affects insulin response and glycemic control in obese individuals. Subjects who consumed this ingredient experienced an increase in blood sugar and insulin levels. 

Furthermore, sucralose may interact with the gut microbiota and trigger chronic inflammation, as reported by Frontiers in Physiology. Saccharin, another popular ingredient in diet soda, may cause liver inflammation

Artificial sweeteners including sucralose increase appetite.

Need one reason to skip this ingredient? Sucralose — and artificial sweeteners in general — increase appetite, causing you to eat more. 

The research is mixed, though, so take these findings with a grain of salt. Consume diet soda in moderation or choose a brand containing natural sweeteners, such as stevia, to stay safe. 

4. Aspartame 

Some experts say that aspartame is one of the most dangerous substances on the market. Others claim that it has little or no side effects. 

As the American Cancer Society points out, most studies linking aspartame and cancer are inconclusive. Both the FDA and the European Food Safety Authority say that aspartame is most likely safe. This artificial sweetener is commonly used in chewing gum, sugar-free ice cream, diet soda, and various foods for diabetics. 

A recent review published in the Nutrition Journal assessed the effects of non-nutritive sweeteners on health. After analyzing 372 studies, researchers concluded that NNSs are neither beneficial nor harmful. Most claims surrounding these additives require further investigation. 

Most studies link the artificial sweetener aspartame to cancer are inconclusive.

For example, 11 studies cited in the above review show a positive association between NNSs and bladder cancer. Other studies show no correlation between the two. 

A widely cited animal study featured in Environmental Health Perspectives refers to aspartame as a multipotential carcinogenic acid

This popular ingredient has been linked to a greater risk of leukemia, malignant brain tumors and other types of cancer. Again, the research was conducted on animals, so it’s unclear how the results translate to humans. 

Beware, though, that artificial sweeteners, including aspartame, may contribute to weight gain, heart disease, metabolic syndrome, and diabetes when consumed regularly. These additives alter glucose metabolism and homeostasis, affecting metabolic health. 

Diet Soda and Body Weight 

Sugar-sweetened beverages fuel the obesity epidemic. Researchers blame them for the rising rates for type II diabetes, non-alcoholic fatty liver disease, cardiovascular problems, and metabolic disorders. Under these circumstances, it makes sense to switch to diet soda. 

Sugar sweetened beverages are blamed for the rise in obesity & type 2 diabetes.

Unfortunately, this beverage isn’t any better than soft drinks. 

Diet soda has been shown to increase abdominal fat mass. Furthermore, drinking three sodas per day may double your risk of becoming overweight or obese in the long run. Several theories exist. 

Drinking 3 or more diet sodas per day can increase the risk of obesity in the long run.

Artificially-sweetened beverages may increase insulin production, affecting glucose metabolism. Over time, the fluctuations in insulin levels can put you at risk for diabetes, abdominal obesity, hypertension, and heart disease. 

Sugar Addiction

On top of that, diet soda tastes good. The more you drink, the more you crave it. This beverage fuels your addiction to sugar, making it harder to eat clean. Plus, you may think of it as a free pass to eat more.  

Artificial sweeteners in beverages fuel the addiction to sugar.

According to a 2012 study featured in Psychology & Behavior, sugar-free beverages alter the processing of sweet taste in the brain. 

However, this doesn’t necessarily mean that drinking diet soda leads to weight gain. It’s your overall diet that matters most (here’s how to calculate your macros for fat loss or hypertrophy). 

  • In a clinical trial, overweight and obese subjects who replaced soft drinks with non-caloric beverages lost 2 to 2.5% of their body weight
  • In another study, dieters who drank 24 ounces of sugar-free beverages daily for 12 months lost approximately 13.7 pounds. Surprisingly, those who consumed water dropped only 5.5 pounds. 

We’re not saying that diet soda is better than water. Most studies supporting the health benefits of diet coke and other sugar-free beverages are funded by the soft drink industry. Therefore, it’s hard to determine their validity.  

Overweight Folks and Diet Soda

Several studies conducted over the years show that consumers of diet soda tend to be overweight. For example, a 2012 review published by the Obesity Society has found that body mass index was 47% higher in subjects consuming sugar-free drinks compared to those who didn’t. 

There’s a believed indirect relationship between diet soda & obesity.

Researchers believe that there may be an indirect relationship between artificially sweetened beverages and weight gain. 

Sugary foods induce a sense of satiety and satisfaction. Cutting back on sugar causes people to eat more protein and fat, which in turn, may increase body weight and fat mass. 

Artificial sweeteners may change food preferences & increase appetite.

Additionally, artificial sweeteners are up to 13,000 sweeter than sugar, which may change your food preferences and increase appetite. According to the above review, some individuals are more sensitive to the effects of non-caloric sweeteners and may experience intense cravings and hunger pangs because of it. 

A new study published this year examined the link between low‐calorie sweetened beverages and calorie intake children. Its findings are quite surprising. 

Children and teenagers who drank diet soda didn’t consume fewer sugars or calories throughout the day. On the contrary — they took in about 200 more calories than those drinking water. 

There’s a catch, though. 

In general, people with a poor overall diet are more likely to drink diet soda to offset the calories consumed from junk food and sugary treats. 

fast food
People with a poor overall diet are more likely to drink diet soda to offset their calories.

Let’s say you order a pizza and two cheeseburgers along with diet coke. That beverage is unlikely to make any difference, considering the number of calories you’re taking in from food.

Sugar-Free Beverages Increase Diabetes Risk 

Think diet soda is healthy because it contains no sugar? Believe it or not, this flavorful beverage can skyrocket your risk of diabetes and its complications. 

diet soda
Although diet soda has no sugar, it can spike the risk of diabetes.

A meta-analysis of 17 cohort studies involving millions of people compared the effects of diet soda, sugar-sweetened beverages, and fruit juice on diabetes risk. Researchers concluded the following:

  • Drinking one sugar-sweetened beverage per day increases diabetes risk by 18% (13% after adjustment for adiposity_
  • The consumption of one daily serving of diet soda raises diabetes risk by 25% (8% after adjustment for adiposity)
  • Consuming one daily serving of fruit juice increases the risk of diabetes by 5% (7% after adjustment for adiposity)
Study participants who preferred diet soda tended to be overweight or obese.

Furthermore, scientists have noticed that the study participants who preferred diet soda tended to be overweight or obese. Their blood pressure was higher too. 

In another study, daily soda consumption raised diabetes risk by 67% and the risk of metabolic syndrome by 36%

Artificial sweeteners increase the risk of diabetes & metabolic syndrome.

Researchers say that artificial sweeteners might be the culprit. Sugar substitutes increase the desire to consume high-calorie foods and drinks, leading to weight gain and metabolic dysfunction. 

However, there is evidence of bias for the associations between sugar-free drinks and diabetes, so these findings are subject to debate. 

Sugar-free drinks increase the risk of insulin resistance and type II diabetes. 

A recent review published in The International Journal of Clinical Practice assessed the link between diet soda and metabolic health. As its authors note, both sugar-free drinks and regular soft drinks may contribute to the onset of metabolic syndrome. This condition is a major risk for insulin resistance and type II diabetes. 

Want to Keep Your Heart Healthy? Skip the Soda

Heart disease is a leading cause of death in the U.S., claiming more than 610,000 lives each year. Obesity, diabetes, lack of exercise, and bad eating all contribute to cardiovascular problems. According to the latest research, soda consumption may play a role too. 

heart disease
Drinking 2 or more diet sodas per day increases the risk of heart disease.

A study published in the journal Stroke earlier this year has found that drinking just two cans of soda diet daily can significantly increase the risk of heart disease, stroke, and all-cause mortality

However, the study was conducted on postmenopausal women, so its findings may not apply to younger women and men. Further research is needed to assess their effects. 

coronary disease
Drinking 2 or more diet sodas per day increases the risk of coronary heart disease.

An older study reported similar findings: subjects who consumed two or more cans of sugar-free beverages per day had a 30 percent higher risk of coronary heart disease and death from all causes than those drinking up to three diet beverages per month.

Diet Soda Wreaks Havoc on Your Brain

Feeling moody and depressed? Your daily soda habit might be the culprit. 

mental health
Consuming diet soda may increase the risk of depression.

According to a large-scale study conducted on 263,925 participants, soda consumption may increase the risk of depression by a whopping 30%. Diet soda further increased the risk by 22%, while coffee was linked to a 10% lower risk of depression. 

Soft drinks may also worsen stress and lead to suicidal thoughts, as reported in a 2010 study featured in Public Health Nutrition

Subjects who drank more than half a liter of soda per day had 60% greater chances of experiencing mental problems, depression, suicidal thoughts, and stress-related disorders than those who didn’t consume soda at all. 

mental problems
Drinking more than half a liter of soda per day had 60% greater chances of experiencing mental problems

The above study doesn’t mention diet soda in particular. However, artificially-sweetened beverages are classified as soft drinks. 

As the researchers point out, artificial sweeteners have neurological effects and may pose greater risks than sugar and honey. 

Another explanation is that people who drink diet soda regularly are more likely to already be depressed without realizing it. If their symptoms flare up, they may blame soda. 

Could Diet Soda Affect Your Physical Performance? 

Nowadays, it’s common to see world-class athletes sipping on diet coke and other sugar-free beverages. Many of them avoid these drinks before competing, though. 

From a nutritional standpoint, diet soda shouldn’t cause you to store fat. The problem is that you don’t really know how aspartame and other chemicals in soda affect your weight in the long run. 

One thing is for sure: soft drinks, including sugar-free varieties, have zero nutritional value

Also, beware that some brands are high in sodium, leading to water retention. However, they may also contain caffeine, which has diuretic effects and keeps you energized. 

Diet soda might not be the best for leaning out as it affects the insulin response.

Assuming that diet soda affects insulin response, this beverage isn’t the best choice for those trying to lean out. But most studies are conflicting. At the end of the day, it’s up to you to decide whether or not this beverage fits into your diet plan.

Is Diet Soda Bad for You? Our Verdict and Some Helpful Tips 

Current evidence suggests that sugar-free beverages may carry potential health risks. Weight gain, abdominal obesity, metabolic syndrome, heart disease, and insulin resistance are just a few to mention. But there are plenty of studies showing that diet soda facilitates weight loss and improves appetite control. 

diet soda
Studies show that diet soda facilitates weight loss & improves appetite control.

If, let’s say, you’re on a low-carb or ketogenic diet, sugar-free beverages can make all the difference. Just make sure you don’t go overboard. 

Water is no doubt the best source of hydration.

Is diet soda bad for you? That’s hard to tell — try it and see how your body reacts. An occasional glass of diet coke is unlikely to affect your waistline. Moderation is the key. 

Healthier Options

Alternatively, seek healthier substitutes for diet soda. If you’re not a fan of plain water, consider the following options:

  • Unsweetened tea — iced or hot
  • Sparkling water with fresh lemon juice
  • Fruit-infused water
  • Homemade caffeinated beverages
  • Freshly squeezed lemonade
  • Mineral water 
lemon soda
Lemon soda is a low calorie refreshing beverage instead of diet soda.

For example, you can make your own version of citrus-flavored soda by mixing sparkling water, lemon or lime juice, and stevia. Another option is to put chopped-up fruit in a jar, fill it with cold water, and add ice for a refreshing beverage with zero calories. 

Iced coffee is another energy boosting beverage that is relatively healthier the diet soda.

Need a quick boost of energy? Blend coffee, vanilla essence, stevia, and ice. You’ll get a foamy beverage that quenches your thirst and energizes your senses. Better yet, add a scoop of protein powder to the mix. 

How often do you drink diet soda? Have you ever tried to kick this habit? Share your thoughts below! 

Disclaimer: None of the individuals and/or companies mentioned necessarily endorse Old School Labs or COSIDLA Inc. products or the contents of this article. Any programs provided for illustration purposes only. Always consult with your personal trainer, nutritionist and physician before changing or starting any new exercise, nutrition, or supplementation program.
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  • This is so thorough! I can’t wait to share this with a few people who could really benefit from eliminating diet soda from their diets!

  • I really dont drink anything but water but i know plenty of fitness people who love diet coke. I will share this with them

  • I like to stick with the natural sweeteners such as stevia. I really appreciate that Old School Labs uses natural sweeteners and no random artificial dyes!

  • I agree with the idea of drinking diet soda in moderation. I would normally drink it when having a cheat meal but that would be about it. To be entirely honest, I’m not a fan of all the artificial sweeteners, regardless if some have no effect on the human body. I’m especially not a fan of caramel color. I do find it interesting though that some studies have shown a small amount of weight being lost when drinking diet soda. I ultimately can’t deliver a verdict on the drink. I don’t think it’s the absolute best and there are better alternatives but, as stated before, it’s not bad to have it in moderation.

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