Yes—people often say that, but the ending of the sentence matters because many claims about drinking water on an empty stomach are exaggerated.
What the evidence supports:
- Drinking water after waking up helps rehydrate you after several hours without fluids.
- If you’re mildly dehydrated, it may temporarily improve alertness and concentration.
- It can contribute to your overall daily fluid intake.
Common claims that aren’t well supported by strong evidence:
- It “flushes toxins” in a unique way beyond what your kidneys and liver already do.
- It causes significant weight loss by itself.
- It cures digestive problems or prevents diseases simply because it’s consumed on an empty stomach.
For most healthy people, drinking a glass of water first thing in the morning is a perfectly reasonable habit, but it’s not a medical cure-all.
If you were referring to a specific claim (for example, “…could be dangerous,” “…could boost metabolism,” or “…could cleanse your body”), let me know which one and I can explain what the research says.
