Neither cold water nor room temperature water is universally “better” for you. Both hydrate you equally well, and the best temperature depends on what you’re doing at the time. Cold water has a slight edge during exercise because it helps manage body heat, while room temperature or warm water is gentler on digestion and better when you’re congested. The calorie-burning benefit of cold water is real but negligible.
Hydration Is the Same Either Way
Your body absorbs water regardless of its temperature. Studies comparing cold water and ice ingestion during exercise found no significant difference in body mass loss between the two, meaning fluid retention was essentially identical. The temperature of your water does not change how well it hydrates you.
What temperature does affect is how much you drink. The American College of Sports Medicine recommends fluids between 59°F and 72°F (15°C to 22°C), which is cool but not ice cold, specifically because people tend to find that range more palatable and drink more of it. If ice-cold water encourages you to keep sipping throughout the day, that’s a net positive. If you prefer room temperature and it keeps you reaching for your bottle, that works just as well.
Cold Water During Exercise
Cold water’s clearest advantage is during physical activity. In a study published in the Journal of the International Society of Sports Nutrition, participants who drank cold water during a 60-minute workout had a significantly smaller rise in core body temperature (0.83°C) compared to those drinking room temperature water (1.13°C). More importantly, the cold water group delayed their core temperature increase for about 30 minutes longer than the room temperature group, whose body temperature started climbing after just 15 minutes.
That said, the performance results were mixed. About half the participants jumped farther and lasted longer on an endurance test with cold water, but those improvements didn’t reach statistical significance. Bench press performance actually dipped slightly in the cold water group. So cold water helps your body manage heat during a workout, but it won’t necessarily make you stronger or faster.
The Calorie-Burning Claim
You may have heard that drinking ice water forces your body to burn extra calories warming the liquid to body temperature. This is technically true, but the effect is tiny. Drinking a glass of ice water instead of room temperature water burns about 8 calories. To put that in perspective, a single saltine cracker has more calories than that.
A more interesting finding comes from a study of overweight children who drank cold water (4°C). Their resting energy expenditure rose by up to 25% above baseline, peaking about an hour after drinking, and staying elevated for over 40 minutes. That sounds dramatic, but the researchers estimated that drinking the full recommended daily amount of water could translate to an additional weight loss of roughly 1.2 kilograms (about 2.6 pounds) per year. That’s a real but very modest effect, and it applies to overall water consumption, not just cold water specifically.
Room Temperature Water and Digestion
Cold water temporarily slows certain digestive functions. A study measuring stomach activity after participants drank 500 mL of water at different temperatures (2°C, 37°C, and 60°C) found that ice-cold water reduced the frequency of stomach contractions compared to warm water. The cold water group also ate less at a subsequent meal, which could be helpful or unhelpful depending on your goals.
For people with swallowing disorders, the difference is more pronounced. Research using high-resolution pressure measurements found that cold water reduced the strength of esophageal contractions in healthy people by roughly a third compared to room temperature water. If you have difficulty swallowing or a condition like achalasia, room temperature or warm water is the safer choice.
Cold Water and Congestion
When you’re sick with a cold or upper respiratory infection, warm or hot liquids are clearly better. A classic study measuring nasal mucus flow found that sipping hot water increased mucus velocity from 6.2 to 8.4 millimeters per minute, helping clear congestion. Cold water did the opposite, significantly decreasing mucus velocity from 7.3 to 4.5 millimeters per minute. That slower clearance means stuffier sinuses. If you’re fighting a cold, stick to warm or hot fluids.
Cold Water and Headaches
If you’re prone to migraines, cold water can occasionally trigger a headache. In a study of 669 women, 7.6% developed a headache after drinking just 150 mL of ice-cold water through a straw. Women with active migraines (at least one attack in the past year) were twice as likely to experience this effect. This doesn’t mean you need to avoid cold water entirely, but if you notice a pattern of headaches after drinking very cold beverages, the connection is well documented.
Cold Water and Sensitive Teeth
Dentin hypersensitivity, the sharp pain you feel when cold hits an exposed tooth surface, is one of the most common reasons people avoid cold water. Research on cold-stimulus pain thresholds found that the temperature triggering moderate to strong pain varied widely between individuals, with an average pain-inducing temperature around minus 14°C (well below what comes out of your fridge). But for people with significant sensitivity, even standard cold tap water can be uncomfortable enough to discourage adequate hydration. If cold water hurts your teeth, room temperature water removes that barrier.
Which Temperature to Choose
The practical answer is straightforward. During or after exercise, especially in warm weather, cold water helps keep your core temperature down. When you’re sick or congested, warm water helps clear your airways. If you have migraines, digestive issues, or sensitive teeth, room temperature water avoids triggering symptoms. For everyday hydration with no special circumstances, drink whichever temperature you enjoy most, because the single biggest factor in staying hydrated is simply drinking enough.