[Tilda Rosander]

Tilda Rosander asked the Naked Scientists:
   My friend claims that his normal body temperature is 35.5 celsius, something that I find strange. My sister has a very high normal body temperature. What makes people have different body temperatures? My friend hardly ever feels cold and my sister does all the time.

Can the difference in the temperature that the body has to maintain play a part in that?

My friend still feels warm to the touch, even more so on the extremities than my sister. Another thing that I have noticed (that is higly unscientific with only two test subjects) is that my friend has a large body mass (fat) and my sister is mostly skin and bones.

What do you think?

[Pwee]

source

The temperature of the body is regulated by neural feedback mechanisms which operate primarily through the hypothalmus. The hypothalmus contains not only the control mechanisms, but also the key temperature sensors.

And also if you want to maintain a higher temperature in the room (body), you will have to burn more fuel (calories), especially, if the room in which you want a warmer temperature has less insulation (fat).
So it might be that your sister is skinnier because her body temperature setpoint is higher and so she uses more of the consumed energy to heat herself rather then store it in fat.

Another thing is that core body temperature often differes from skin temperature, so it is possible that your friend has the same core temperature as others, but his skin is cooler.

[Nizzle]

The hypothalamus is your body's thermostat.