[romdev]

From Tim Ferris' 'The 4-hour Body', an even more important tool for toning and weight loss is to stay cold. Olympic swimmers consume more calories than the average athlete even though their exertion is less. A pool is kept well below body temperature and your body uses those calories to keep itself warm. His advice was to sleep with a sheet instead of a blanket, unless you're swimming 5 hours a day.

[chkaloon]

Agreed. I've had to do outdoor winter work the last few years in Alaska, and I can attest that will burn those calories off.

[paulpauper]

not that much https://www.livestrong.com/article/366425-how-swimming-in-co....

A study performed at the University of Florida showed slightly more calories are burned in cold water exercise than in warm. In the study, men who exercised for 45 minutes in 68 degree water burned an average of 517 calories. The men who exercised in 91.4 degree water burned 505 calories, on average.

from very cold to very warm is just twelve extra calories

But even in that case, you’d only burn a few additional calories at best, Cypess said. In studies where he’s put participants in cold rooms for entire days, they burned off an additional 150 to 200 calories. Again, that’s a full day of cold — not an hour’s worth of outdoor activity.

https://www.vox.com/2017/12/23/16774320/exercise-in-cold-bur...

vast majority of energy is expended by exhalation of carbon dioxide, not warming

[listenallyall]

In most locations around the globe, the air temperature is well below body temp. What's the difference?

[edwardsdl]

Water is a much, much better conductor of heat than air.

[listenallyall]

Which means what, in this example, exactly? A person in a 60 degree pool is losing more internal body heat than a person simply standing outside in 60 degree weather? Is it still so, if it's a 70 degree pool vs 40 degree weather, or 24 hours at room temp vs one hour in a pool?

[edwardsdl]

Just a disclaimer, I’m not an expert in this area.

Yes, a person in 60° water is losing heat energy more quickly than someone in 60° air. This is because water is much more efficient at transferring this energy - something like 24x IIRC.

Determining an equivalent air temperature requires knowing a bunch of additional factors (e.g. humidity). I don’t know of a rule of thumb you could apply other than saying the equivalent air temperature of water below one’s body temperature would be much colder, and the inverse would be true for water temperatures above one’s body temperature.

[listenallyall]

Makes sense. Obviously I need a refresher course on thermodynamics.

[xk_id]

This is why appetite increases in winter.