Drinking water first thing in the morning is an increasingly popular practice, often presented as an essential health habit. But beyond the trends, what does science actually say about this habit? What are the proven effects, and how can you effectively integrate it into your daily routine? We'll explore this in this article.
Why drink water on an empty stomach upon waking?
Rehydrate the body after a night's sleep
During sleep , your body continues tolose fluid through respiration and perspiration. The amount of fluid lost varies depending on the climate and respiratory ventilation. Once awake, your body is therefore in a state of mild dehydration. A glass of water on an empty stomach will help compensate for this deficit and restore fluid balance .
Boost your metabolism first thing in the morning
Drinking about 500 ml of water can lead to a temporary increase in energy expenditure , usually lasting for about an hour. This phenomenon is called water-induced thermogenesis : the body expends energy to adjust the water's temperature to its own. While results vary from study to study, this demonstrates that morning hydration can boost your metabolism by promoting more efficient use of available energy.
Promote the proper functioning of the digestive system
Drinking water on an empty stomach helps restart intestinal function after several hours of sleep . Water acts as a natural lubricant , facilitating the movement of food and the action of digestive enzymes . It also plays an important role in the delivery and distribution of nutrients to the organs . If you are prone to constipation, this ritual can also improve your digestion .
Detoxify the body gently
Contrary to popular belief, water does not directly "cleanse" the body . Your kidneys and liver perform this function by filtering and processing metabolic waste . However, adequate hydration facilitates the work of these organs by supporting their natural ability to eliminate toxins .
Improve concentration and mental clarity
Even if minimal (1 to 2% of body weight), the Dehydration can impair your performance Cognitive impairment can reduce alertness , affect working memory, and increase feelings of fatigue. After a night's sleep, rehydrating helps restore mental clarity and optimal alertness.
What effects have been proven by science?
Drinking water and regulating body temperature
Water plays a central role in maintaining body temperature . It participates in perspiration, a natural mechanism that eliminates excess heat.
Maintaining good hydration also promotes blood circulation , which is necessary for the distribution of heat in the tissues. Studies show that even a slight dehydration disrupts the thermoregulation .
The impact on the kidneys and the elimination of toxins
Every day, your kidneys continuously filter the blood to remove metabolic waste and depend on sufficient fluid intake to function efficiently . After sleep, your urine is more concentrated in toxins , a sign that the body has been functioning with little fluid. Drinking will help dilute it and facilitate the elimination of metabolic waste .
Does drinking water on an empty stomach help with weight loss?
In overweight adults, consuming 500 ml of water before meals resulted in modest weight loss after a few weeks, according to a This is mainly due to the feeling of fullness provided by water and, to a lesser extent, to the slight stimulation of metabolism after ingestion. Drinking on an empty stomach can indirectly help you lose weight , provided you maintain a balanced diet and regular physical activity .
Warm water, cold water, lemon water... what to choose in the morning?
The benefits of drinking lukewarm water on an empty stomach
In In Ayurvedic medicine , it is often recommended to drink lukewarm water upon waking . Its warmth, close to that of the body, aids digestion and stimulates intestinal transit . It is also better tolerated than very cold water, especially if you are prone to acid reflux.
When is lemon water preferable?
A few drops of lemon added to water provide vitamin C , an antioxidant that promotes vitality and reduces fatigue . Lemon also gives it a pleasant taste , which will be helpful if you find plain water too bland.
Should we avoid cold water in the morning?
For most people, cool water is pleasant and safe . However, drinking it first thing in the morning can cause a slight thermal shock and slow digestion in some individuals. If you have a sensitive stomach, it would be best to opt for lukewarm or room-temperature water.
Recommended types of water (mineral, filtered, etc.)
In France, Tap water undergoes strict health controls and is safe to drink every day. It also has the advantage of being economical and environmentally friendly. However, you can filter it using a water dispenser or a filter pitcher.
Mineral waters contain significant amounts of minerals such as sodium , magnesium, and calcium. They are necessary in situations requiring specific nutrients, such as during physical activity or in hot weather.
How can I easily adopt this habit?
How many glasses of water should you drink upon waking?
One or two glasses of water (200 to 300 ml) are enough to rehydrate. The important thing is to listen to your body and not force yourself to drink excessive amounts . Swallowing too much liquid at once can cause digestive discomfort , nausea , or, in rare cases , hyponatremia (a temporary decrease in blood sodium levels).
With or without food: which is the best practice?
Hydrating before or during meals , including breakfast, does n't significantly impact digestive function. Whether you drink before, during, or after, water aids digestion and facilitates nutrient absorption. The key is to listen to your body and avoid overindulging.
Create a morning routine centered around water
Consistency is key. For example, you can:
- Place a glass or a water bottle on your bedside table before going to bed.
- Download a reminder app.
- Associate each dose with a habitual action (brushing teeth, preparing coffee or meditation).
These small rituals will help you transform a simple intention into an automatic gesture.
Warnings and misconceptions
No, drinking water on an empty stomach does not "melt" belly fat
Water doesn't have "fat-burning " properties. However, it can increase satiety and help prevent snacking . This can contribute to reducing abdominal fat , provided you maintain a balanced diet and engage in regular physical activity, as we explained earlier.
When should you avoid drinking too much water on an empty stomach?
If you suffer from kidney or heart problems , or are taking diuretics , you should first seek advice from your doctor .
What do healthcare professionals say?
Most nutritionists and doctors consider hydrating before meals a healthy habit . The key is to maintain a regular intake throughout the day and not focus solely on the moment of eating.
FAQ - Drinking water on an empty stomach
Is it good to drink water on an empty stomach?
Yes. It helps compensate for fluid loss that occurs overnight. This routine supports kidney function, gently stimulates the digestive system, and contributes to better metabolic balance.
Is it safe to drink water on an empty stomach during intermittent fasting?
Yes. Unlike some drinks, it contains neither calories nor nutrients. It even promotes tolerance to intermittent fasting by reducing feelings of hunger.
Does drinking water on an empty stomach really help you lose weight?
Only indirectly. Water doesn't directly affect fat burning, but it can increase feelings of fullness and help you eat less. Weight loss is possible in the long term with a balanced diet and regular exercise.
Should you prefer hot, warm, or cold water in the morning?
It all depends on your digestive comfort and preferences. Warm for gentleness, cold for a tonic effect, hot to soothe some sensitive stomachs.
Is lemon water more effective?
It is no more effective. On the other hand, lemon provides vitamin C and antioxidants and offers greater nutritional value.
In summary: a simple, but powerful habit
Key points to remember to effectively integrate this routine
Drinking water on an empty stomach is a simple, accessible, and easy habit to adopt . The key is to drink one or two glasses of water , without overdoing it, and then continue to hydrate regularly throughout the day. Whether you prefer lukewarm, chilled, or lemon water , consistency is key. Associating this habit with a daily ritual , such as brushing your teeth or preparing a meal, will help you establish it as a lasting habit.
The long-term health benefits
Practiced regularly, this reflex contributes to better fluid balance , supports kidney function , promotes digestion , and helps maintain cognitive alertness . It does not replace a balanced diet or physical activity, but it is an important part of your well-being.
Bibliography
Boschmann, M., Steiniger, J., Hille, U., Tank, J., Adams, F., Sharma, A.M., Klaus, S., Luft, F.C., & Jordan, J. (2003) . Water-induced thermogenesis. The Journal of Clinical Endocrinology & Metabolism, 88 (12), 6015–6019.https://doi.org/10.1210/jc.2003-030780
Ganio, MS, Armstrong, LE, Casa, DJ, McDermott, BP, Lee, EC, Yamamoto, LM, & Marzano, S. (2011). Mild dehydration impairs cognitive performance and mood of men. British Journal of Nutrition, 106 (10), 1535–1543.
https://doi.org/10.1017/S0007114511002005
Sawka, MN, Latzka, WA, Matott, RP, & Montain, SJ (1998) . Hydration effects on temperature regulation. International journal of sports medicine, 19 Suppl 2, S108–S110. https://doi.org/10.1055/s-2007-971971
Nakamura, Y., Watanabe, H., Tanaka, A., Yasui, M., Nishihira, J., & Murayama, N. (2020) . Effect of Increased Daily Water Intake and Hydration on Health in Japanese Adults. Nutrients , 12 (4), 1191. https://doi.org/10.3390/nu12041191
Dennis, EA, Dengo, AL, Comber, DL, Flack, KD, Savla, J., Davy, KP, & Davy, BM (2009) . Water consumption increases weight loss during a hypocaloric diet intervention in middle-aged and older adults. Obesity (Silver Spring), 18(2), 300–307.
https://doi.org/10.1038/oby.2009.235
Mayo Clinic Staff. (2025, September 5). Does drinking water during or after a meal help or harm digestion? Mayo Clinic.
Scharfetter C. (1976) . Ayutveda [Ayurveda]. Schweizerische medizinische Wochenschrift , 106 (17), 565–572. https://pubmed.ncbi.nlm.nih.gov/982009/
