No, drinking cold water does not cause weight gain. This is a myth with no scientific basis. Here's what the physiology actually shows:

Thermic effect (minor calorie burn): When you drink cold water (e.g., ~4°C), your body expends a small amount of energy — roughly 8 calories — to warm it to core body temperature (37°C). This is a trivially small amount and does not meaningfully affect metabolism in either direction.

No fat storage mechanism: Water contains zero calories, so regardless of its temperature, it cannot be converted to fat or stored as body mass. The water temperature has no effect on fat metabolism.

Digestion: The claim that cold water "solidifies fat" during digestion or "slows digestion" is not supported by physiology. The GI tract is highly effective at regulating its own environment; ingested water equilibrates to body temperature within minutes of reaching the stomach.

The belief is common in some traditional medicine systems (e.g., Ayurveda, Traditional Chinese Medicine), which associate cold foods/drinks with sluggish digestion or "dampness." These are cultural frameworks, not biomedical ones.

Weight change is governed by energy balance — total caloric intake vs. expenditure. Water temperature plays no role. Factors that do matter:

Some small studies suggest drinking water before meals — regardless of temperature — can modestly reduce appetite and caloric intake, potentially supporting weight management rather than hindering it. Cold water may also improve exercise performance by preventing overheating, indirectly supporting activity levels.

Bottom line: Cold water does not cause weight gain. If anything, staying well-hydrated (with water at any temperature) is associated with healthier body weight outcomes.