Why water heat capacity has minimum at body temperature?

Where the body-temperature claim comes from

Heat capacity is simply how much energy you must add to raise a given amount of a substance by one degree. For liquid water it is unusually large, which is why water resists temperature swings and why the body's water content is so useful for holding temperature steady [2]. A model of liquid water built from its heat capacity, spectra, and density does describe a minimum in heat capacity, but it places that minimum at high temperatures rather than at body temperature [1].

That mismatch is the heart of the confusion. The paper that actually analyzes a heat-capacity minimum never treats body temperature as a special or relevant condition [1]. The papers that do discuss body temperature are about physiology, not about a dip in water's heat capacity [3][4]. Putting the two together produces a claim that neither body of work supports.

What the body-temperature papers actually show

The physiology evidence concerns regulation and performance, not the physical properties of water. Body water and blood volume shape how well a person handles heat and how they perform in hot conditions, and these adapt with heat acclimation [2]. Warming the body, whether through exercise or passive heating, can raise work capacity [4]. Separately, many mammals can lower their core temperature on a daily basis, and this ability tracks environmental temperature and productivity [3].

None of these findings measures heat capacity as a function of temperature, and none reports a minimum at 37 °C [2][3][4]. They describe the body as a system that manages temperature, which is a different question from how water's heat capacity varies with temperature.

Why water still matters for keeping body heat steady

The practical point survives even though the specific claim does not. Because water holds a lot of heat for its mass, the body's water and blood volume are central to thermoregulation and to performance in the heat [2]. That large heat capacity is a general property of liquid water, not something that peaks or bottoms out at body temperature.

So the useful takeaway is that water's heat capacity is high, and the body exploits that. The idea of a minimum at body temperature is a misattribution: the minimum described in the water model sits at high temperatures [1], while the body-temperature literature is about regulation and work capacity [2][4].

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