Nutrition Diet: Does Coca-Cola Hydrate More Than Water, Or Is It a Myth?

October 16, 2025 •

4 min read

According to a controversial 2016 study, beverages like skim milk, orange juice, and cola ranked as more hydrating than plain water over a short period. However, the complex truth behind the question, 'Does Coca-Cola hydrate more than water?' involves looking past a single short-term metric and considering overall health.

Quick Summary

A sugary cola is not a healthier or more effective source of long-term hydration than water. The high sugar content, additives, and lack of nutritional value make it a poor choice for meeting daily fluid needs despite being mostly water.

Key Points

Misleading Metrics: A controversial Beverage Hydration Index (BHI) study suggested cola is more hydrating over a 4-hour period, but this oversimplifies the science and ignores long-term health consequences.
High Sugar Content: Coca-Cola contains a large amount of added sugar, which can lead to blood sugar spikes, weight gain, type 2 diabetes, and forces the body to use extra water for processing, potentially worsening dehydration.
Mild Diuretic Effect: The caffeine in many sodas acts as a mild diuretic, causing increased urination and contributing to fluid loss over time.
Detrimental to Health: Regular soda consumption is linked to dental erosion, kidney strain, and an increased risk of chronic diseases, making it a poor choice for overall nutrition.
Water is Superior: Plain water is the optimal choice for hydration, as it is calorie-free, sugar-free, and essential for all major bodily functions without any negative side effects.
Healthy Alternatives: If plain water is unappealing, healthier alternatives like infused water, herbal teas, or plain sparkling water can provide effective hydration without compromising health.
Thirst Perception: The carbonation and cold temperature in soda can temporarily trick the body into feeling more quenched, potentially leading to lower overall fluid intake throughout the day.

The Beverage Hydration Index: A Closer Look

The idea that soda might be more hydrating than water stems from a 2016 study published in the American Journal of Clinical Nutrition. The study compared the hydrating effects of several drinks by measuring fluid retention over a four-hour period, a metric termed the Beverage Hydration Index (BHI). Some drinks with higher levels of electrolytes, sugar, or protein—such as milk, oral rehydration solutions, and orange juice—showed a slightly higher BHI than still water. Cola also appeared to score well on this short-term index due to its sugar and sodium content, which can temporarily slow the emptying of fluid from the stomach.

However, this metric is often misunderstood and does not tell the whole story of nutritional health. The study, funded by the European Hydration Institute (which has ties to the dairy industry), has been criticized for oversimplifying the science of hydration. While a cold, carbonated beverage might feel refreshing and quench thirst more quickly due to the bubbles and temperature, this can also lead people to drink less overall, which is counterproductive. Moreover, the temporary fluid retention from soda comes at a significant cost to overall health.

Why Water Remains the Gold Standard for Hydration

Water is the single most essential liquid for the human body, involved in numerous critical functions. It is calorie-free and sugar-free, making it the ideal choice for meeting daily fluid needs without introducing harmful additives. The kidneys and liver rely on water to flush toxins from the body, a process that is hampered by excessive sugar intake. For the vast majority of people, water is the best and simplest choice to maintain proper hydration and support overall bodily function.

The Hidden Costs of Hydrating with Coca-Cola

While soda is composed mostly of water, the other ingredients prevent it from being a healthy or effective hydration source. The negative health impacts of relying on soda for fluids far outweigh any potential short-term fluid retention benefits.

The Sugar Factor

One of the most significant concerns with Coca-Cola is its extremely high sugar content. A standard 12-ounce can contains nearly 9 teaspoons of sugar. The body must expend energy to process this high sugar load, which can lead to blood sugar spikes and crashes and, over time, contribute to weight gain, obesity, and type 2 diabetes. High sugar intake can also trigger increased urination as the body attempts to eliminate the excess glucose, which can worsen dehydration.

The Mild Diuretic Effect of Caffeine

Many types of soda, including colas, contain caffeine. Caffeine is a mild diuretic, which means it increases urine production and can lead to increased fluid loss. While the effect of a single soda is minor and transient, relying on caffeinated beverages can contribute to a cycle of fluid loss that is not conducive to optimal hydration.

Renal and Dental Health Risks

Studies have shown that repeatedly rehydrating with sugary beverages can exacerbate dehydration and worsen related renal damage. The high concentration of fructose and glucose can increase oxidative stress in the kidneys. Additionally, the combination of high sugar and acid in soda is extremely damaging to dental health, eroding tooth enamel and causing cavities.

Comparison Table: Water vs. Coca-Cola

To put the differences into perspective, consider this direct comparison:


Feature	Water	Coca-Cola
Calories	0	140+ (per 12 oz)
Sugar	0g	39g+ (per 12 oz)
Added Ingredients	None	High-fructose corn syrup, caramel color, phosphoric acid, natural flavors, caffeine
Electrolytes	Trace minerals (depending on source)	Some sodium, but inadequate for rehydration
Diuretic Effect	None	Mild (from caffeine)
Dental Impact	Neutral to beneficial	Highly erosive due to acid and sugar
Nutritional Value	No calories, essential for health	Empty calories, zero nutritional benefits
Kidney Impact	Supports kidney function	Linked to increased kidney stress and damage

How to Improve Your Hydration Habits

For those who find plain water unappealing, there are many healthy alternatives that provide excellent hydration without the negative health consequences of soda. These options help you meet your daily fluid needs in a much healthier way.

Here are some better choices:

Infused Water: Add sliced fruits like lemon, cucumber, or berries for a refreshing, flavorful twist.
Herbal Teas: Chamomile, peppermint, and ginger teas are hydrating and contain antioxidants.
Coconut Water: A natural source of electrolytes that aids in rehydration.
Sparkling Water: Plain carbonated water is just as hydrating as still water and can satisfy a craving for bubbles without the sugar.
Electrolyte-Enhanced Water: For intense exercise, choose electrolyte-rich drinks with no added sugar.

Conclusion: The Best Choice for Your Health

While some short-term studies, potentially influenced by industry funding, might suggest that a beverage like Coca-Cola could be slightly more hydrating than water over a very specific time frame due to its sugar and electrolyte content, this is a misleading conclusion. The science is clear: relying on soda for hydration is detrimental to your health. The high sugar content, empty calories, and other additives in Coca-Cola lead to numerous health problems, including dental decay, weight gain, and kidney strain. For proper, sustained hydration that supports your body's overall function and well-being, water is, and will always be, the superior choice. Choose hydration wisely and nourish your body with what it truly needs.

For more information on the impact of soft drinks on health, consult a credible health resource like the NIH or a registered dietitian.

[NIH link: https://pmc.ncbi.nlm.nih.gov/articles/PMC1829363/]

Frequently Asked Questions

Yes, drinking soda instead of water is generally bad for you. While soda contains water, its high sugar content, calories, and other additives can lead to numerous health issues, including weight gain, diabetes, dental problems, and kidney issues.

The caffeine in soda can act as a mild diuretic, which means it increases urine production and can cause a minor, temporary increase in fluid loss. However, at the low levels found in most sodas, this effect is minimal and transient.

A 2016 study found that beverages with sugar and electrolytes, like milk and cola, led to greater short-term fluid retention than water. This is because these components can slow stomach emptying and improve fluid absorption. However, this metric does not account for the negative health effects of high sugar intake.

High sugar content can paradoxically hinder effective hydration. The body must use water to process the sugar, and high blood sugar levels can increase urination as the body tries to excrete the excess glucose, potentially worsening dehydration.

While a small amount of Coca-Cola won't cause severe dehydration if you are otherwise drinking enough water, it is not an ideal method for maintaining fluid balance. It’s best to consume soda in moderation as part of a balanced fluid intake that is primarily water.

Diet sodas are not significantly better for hydration than regular sodas and offer no nutritional benefits. While they don’t contain sugar or calories, artificial sweeteners and other additives can still have negative health impacts and contribute to unhealthy food cravings.

Choosing water over soda supports vital bodily functions like detoxification, aids in weight management by avoiding empty calories, and protects dental and kidney health. It provides effective hydration without any negative side effects.