Why a Glass of Water is the First Thing You Should Consume in the Morning

December 13, 2025 •

4 min read

After sleeping for eight hours, your body becomes mildly dehydrated, which can impact cognitive performance and slow metabolism. Experts suggest drinking water is the first thing you should consume in the morning to replenish fluids, reset your system, and prepare for the day ahead.

Quick Summary

Rehydrating with water immediately upon waking is key for boosting metabolism and brain function after an overnight fast. This simple habit supports digestion and flushes toxins, setting a healthy tone for your entire day.

Key Points

Start with Water: The first thing you should consume in the morning is a glass of water to rehydrate your body after an overnight fast.
Boost Your Metabolism: Drinking water upon waking can increase your metabolic rate by up to 30%, helping to burn more calories throughout the day.
Enhance Brain Function: Mild dehydration can impair mental clarity and concentration; rehydrating improves blood flow to the brain, enhancing focus.
Aid Digestion: Water helps to stimulate the digestive system, promotes regular bowel movements, and assists in flushing out toxins.
Avoid Sugary Drinks: Skip fruit juices and sugary beverages early in the morning to prevent blood sugar spikes and energy crashes later on.
Hydrate Before Coffee: Drink water before your morning coffee to counteract caffeine's mild dehydrating effects and avoid potential stomach discomfort.

Waking up starts with a decision, and for your health, that first decision should be to drink a glass of water. While the allure of coffee is strong for many, rehydrating with plain water is the most beneficial first step for a body that has gone without fluids for hours. This simple act jumpstarts critical bodily functions, from metabolism to brain activity, and primes your system for a healthy day.

The Science of Morning Dehydration and Rehydration

During sleep, your body performs essential recovery and repair functions, all of which consume water. Since you're not drinking overnight, your body wakes up in a state of relative dehydration. This fluid deficit can lead to a decrease in mental performance, including reduced alertness and concentration.

Drinking water first thing in the morning addresses this deficit directly. It helps replenish the fluids lost overnight and aids in several key processes:

Boosts Metabolism: Research indicates that drinking water in the morning can temporarily increase your metabolic rate. One study found that consuming about 17 ounces (0.5 liters) of water can increase a person's metabolic rate by 24–30% for up to an hour. This effect helps your body burn calories more efficiently from the start of the day.
Enhances Brain Function: Since the brain is roughly 75% water, even mild dehydration can impair brain function. Rehydrating first thing improves blood flow to the brain, which in turn can boost mental clarity, alertness, and focus.
Aids Digestion and Clears Waste: Water is crucial for a healthy digestive system. An early morning glass of water helps stimulate intestinal activity and soften stools, promoting regular bowel movements and preventing constipation. It also assists the kidneys in flushing out waste and toxins accumulated overnight.

Water vs. Other Morning Beverages

While many people reach for coffee or juice, they don't offer the same benefits as plain water on an empty stomach. Caffeine can be dehydrating and may cause acid production in some people, leading to discomfort. Sugary juices can cause a rapid spike and subsequent crash in blood sugar, offering a fleeting energy boost followed by fatigue.

For those who prefer a little more flavor, adding a slice of lemon to warm water can provide additional benefits. The vitamin C in lemons supports the immune system and can give a gentle nudge to the liver's natural detoxification processes. However, the most significant benefits are attributed to the water itself, regardless of additives.

The Importance of a Balanced Breakfast

After hydrating, fueling your body with a nutritious meal is the next step. While water gets your system going, a balanced breakfast provides the sustained energy and nutrients needed for the day. A healthy breakfast should contain a mix of protein, fiber, and healthy fats, avoiding processed foods or high-sugar options. Combining these components helps stabilize blood sugar, maintain satiety, and prevent energy crashes.

The Morning Fuel-Up Plan

Rehydrate: Drink 1-3 glasses of warm or room-temperature water immediately upon waking. You can add a squeeze of lemon for extra flavor and vitamin C.
Move: Engage in light exercise or stretching. This further increases blood flow and prepares your body for the day.
Wait: Give your body 15-30 minutes to absorb the water and kickstart digestion before consuming food.
Eat: Enjoy a balanced breakfast featuring complex carbs, protein, and healthy fats.

Making the Right Choice: A Comparison Table

Here is a side-by-side look at how different morning beverage choices stack up.


Feature	Water (Plain or with Lemon)	Coffee (Black)	Fruit Juice (Store-bought)
Primary Benefit	Rehydration, metabolism boost, enhanced brain function, toxin flushing	Caffeine-induced alertness, antioxidants	Vitamins, minerals, quick sugar boost
Impact on Hydration	Excellent. Directly rehydrates the body after sleep.	Mildly dehydrating due to caffeine's diuretic effect.	Hydrating, but high sugar content can be a negative.
Effect on Metabolism	Increases metabolic rate by up to 30%.	Mild metabolic boost from caffeine.	Can lead to rapid blood sugar spike and crash.
Digestive Effect	Stimulates digestive system, softens stool, and aids detox.	Can increase stomach acid, potentially causing discomfort for some.	The lack of fiber from juicing can overwhelm the digestive system.
Best Time to Consume	First thing in the morning to rehydrate.	After water and a light snack to avoid stomach acid issues.	With breakfast to balance the sugar content with fiber and protein.

Conclusion: Start Your Day with the Right Fuel

There is a clear consensus among health experts: the first thing you should consume in the morning is water. After hours of sleep, your body's systems need to be gently revived with a boost of hydration, not shocked with acidic coffee or sugary juice. This simple, free, and effective practice sets the stage for optimal metabolism, brain function, and digestion throughout the day. By making water your first choice, you empower your body to perform at its best from the moment you wake up. For more detailed information on metabolic health and nutrition, visit the National Institutes of Health.

Frequently Asked Questions

Warm or room-temperature water is often recommended as it is gentler on the digestive system. However, some studies suggest cold water might have a minimal effect on boosting metabolism as your body expends energy to warm it up.

There is no exact rule, but a good starting point is one to three 8-ounce glasses (approximately 250-750 ml) to begin rehydrating your system effectively.

Yes, drinking water before brushing your teeth is safe and can even be beneficial. The saliva in your mouth overnight contains beneficial bacteria, and drinking water helps wash it down to aid digestion and support your immune system.

It's best to wait about 15 to 30 minutes after drinking water before having your breakfast. This allows your body to absorb the hydration and gives your digestive system a gentle kickstart.

Plain water offers the core benefits of hydration and metabolic boost. Adding a squeeze of lemon provides an extra dose of vitamin C and antioxidants, supporting the immune system and liver.

Yes, it can. Drinking water in the morning can boost metabolism and increase feelings of fullness, which may reduce calorie intake during breakfast. Replacing sugary drinks with water also helps.

For most people, there are no significant downsides. The only risk is drinking an excessive amount too quickly, which can cause temporary bloating or discomfort. Listening to your body is key.