Does Drinking Cold Water Actually Burn Calories?

Yes, but barely: warming a glass of ice-cold water to body temperature takes a real, calculable amount of energy — roughly 15–20 calories for a typical 500 mL serving — and a separate, well-studied effect shows drinking water also temporarily raises metabolic rate on its own. Neither effect comes close to the scale needed for meaningful weight loss.

The Physics Behind the Claim

This part of the myth is just thermodynamics, and it's genuinely true. Water's specific heat capacity — a well-established physical constant — is 1 calorie per gram per degree Celsius, meaning it takes exactly that much energy to raise one gram of water by one degree. A 500 mL glass of ice water, roughly 500 grams, starts around 4°C (39°F) and has to reach the body's core temperature of about 37°C (98.6°F) — a roughly 33-degree climb. Multiplying it out (500 grams × 33 degrees × 1 calorie) works out to around 16,500 small calories, or about 16–17 food Calories (kcal), that the body spends warming that water up. It's real energy expenditure. It's also roughly what you'd burn climbing two flights of stairs.

The Separate Study Behind "Water Boosts Metabolism"

A frequently cited 2003 study in the Journal of Clinical Endocrinology and Metabolism, led by Michael Boschmann, found something distinct from the temperature effect: giving 16 healthy adults 500 mL of water raised their energy expenditure by 24% over the following 60 minutes, measured by indirect calorimetry. Critically, the same volume of saline solution produced no such increase, and heart rate and blood pressure didn't change — which points to the water itself, likely through its effect on blood volume and the sympathetic nervous system, rather than its temperature, as the driver. The study didn't test cold water specifically against room-temperature water, so it doesn't actually support the "cold" half of the popular claim.

Why Neither Effect Adds Up to Real Weight Loss

Put both effects together — the ~16–17 calories from warming the water, plus whatever modest, short-lived boost comes from the metabolic effect — and the total is a tiny fraction of a typical adult's resting energy use, which runs somewhere in the range of 1,600 to 2,000-plus calories a day depending on body size and activity level. Drinking a few extra glasses of cold water a day might add up to the rough equivalent of a few bites of food over the course of a week. That's not nothing, but it's not a weight-loss strategy on its own, and temperature isn't the part of water drinking that actually moves the needle.

So Does Temperature Matter at All?

Not in any way that's been clearly demonstrated. The Boschmann study's 24% metabolic bump came from giving people 500 mL of water versus the same volume of saline — both presumably at a similar, non-extreme temperature — which isolates the volume and composition of what was drunk, not how cold it was. No widely cited study has directly compared ice-cold water against room-temperature water to isolate a temperature-specific metabolic effect. The only piece of the popular claim that temperature genuinely explains is the basic thermodynamic one covered above — the ~16–17 calories the body spends warming the water itself — and that's a fixed, small number regardless of which study you're reading.

Where Water Genuinely Helps With Weight Management

The more useful mechanism isn't thermogenic, it's behavioral. A 2010 randomized study in the journal Obesity, led by Elizabeth Dennis and Brenda Davy at Virginia Tech, had adults aged 55–75 drink 500 mL of water before each meal while following a reduced-calorie diet. Over 12 weeks, the water-drinking group lost about 2 kilograms more than the group following the same diet without the water preload — a 44% greater decline in weight — and ate measurably less at test meals. The likely mechanism is simple: a glass of water before eating takes up stomach volume and blunts appetite, which is a very different, and considerably more useful, effect than anything related to the water's temperature.

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This article is for general informational purposes only and is not medical or nutritional advice. Anyone considering a weight-management plan, especially alongside existing health conditions or medications, should talk with a doctor or registered dietitian.

Sources: Boschmann et al., "Water-Induced Thermogenesis," Journal of Clinical Endocrinology and Metabolism, 2003, 88(12):6015–6019 • Dennis, Dengo, Comber, Flack, Savla, Davy & Davy, "Water Consumption Increases Weight Loss During a Hypocaloric Diet Intervention in Middle-Aged and Older Adults," Obesity, 2010, 18(2):300–307 • calculation of water's specific heat capacity (1 cal/g°C), a standard physical constant