“Drinking ice-cold water helps you burn extra calories.”
Moderate confidence because human calorimetry studies find at most a small, short-lived energy-expenditure effect from very cold water, and results on water-induced thermogenesis are inconsistent. The effect is far too small to establish meaningful weight loss.
Your body must warm very cold water, and a small study measured a brief increase in energy expenditure. The amount is trivial as a weight-loss strategy.
Claims often turn a basic heat calculation into a precise calorie promise. Human measurements do not support a large metabolic boost, and drinking water instead of a calorie-containing beverage matters much more than water temperature.
Safety note: Cold water is safe for most people. Drinking excessive water of any temperature can cause dangerous low blood sodium, and people doing prolonged exercise or working in heat may need a planned fluid and electrolyte strategy.
Talk to a healthcare professional if: Ask for individualized fluid guidance if you have heart, kidney or liver disease, take diuretics, have recurrent low sodium, or exercise for long periods in heat.
Choose cold or room-temperature water by comfort. Do not expect ice water itself to produce meaningful fat loss.
Use water temperature you enjoy and focus on sustainable food, activity and beverage choices rather than thermogenesis math.