Hydration to Optimize Metabolism

Inclusion Criteria: * Provision of informed consent, age 20-75 years with high plasma concentration of vasopressin (plasma concentration of copeptin of \> 6.1 pmol/L in women and \> 10.7 pmol/L in men) and 24 hour urine osmolality \> 600 milliosmol (mOsm) /kg water. Exclusion Criteria: * 24 hour urine volume \> 1.5 L, pregnancy or breastfeeding, plasma sodium \< 135 mmol/L, use of diuretics, lithium or selective serotonin reuptake inhibitor (SSRI) drugs, chronic kidney disease (estimated glomerular filtration rate \< 30 mL/min), heart failure, inflammatory bowel disease, type 1 diabetes or type 2 diabetes treated with insulin, vulnerable subjects (subjects with legal guardian, with loss of personal liberty).