Yes -- you can burn calories just by sitting in a sauna -- that's because your body has to work to cool itself down. Be careful -- too much sweating is not a good thing -- especially if you don't have enough fat to burn off -- I was getting dizzy spells, and found out I was burning off muscle tissue and damaging organs from my hard core Bikram (hot yoga) practice. My doctor told me to stop it... no amount of rehydration would help me... I stopped; the dizzy spells never came back, and I feel much better now!

yes, when you get hot, you sweat more which helps you lose weight. like a sauna. but it's not rele good for you most of the time. this happens because your body needs to work to cool itself down.

Yes. According to several sources I've researched, prolonged exposure to extremely warm or very cold environments increases your Basal Metabolic Rate (BMR), the number of calories your body burns when at rest just to maintain/sustain life functions. People who live in these type of extreme temperature settings often have BMR's that are 5-20% higher than those in more moderate climates. Cold temperatures have a greater effect on your BMR, to create the extra heat necessary to maintain a stable internal body temperature. Short exposure to hot temps won't increase metabolism too significantly, but prolonged exposure will cause an increase in BMR. Ref: http://www.pacificfit.net/article15.htm http://www.weight-loss-program.com/art04-metabolism.html http://www.nriol.net/basal-metabolic-rate-calculator.asp

You seem to have all the answers here however I would like to add my twopence worth: Temperatures help greatly when exercising, if you work towards that specific heat/cold training, such as eating the correct food groups before exercising in the cold. I think the best training for short term gain (such as just before a big competition) is altitude training. One can really increase one's efficiency of metabolic rate by training at high altitudes for just a week or two. The lower levels of oxygen mean one shouldn't dive in in at the deep end and take a rowing machine up there to do a one hour session, but build up gradually.

psych31 is right, though not specifically answering the question. You're Basal is measured at complete rest after food is completely digested(approx. 12 hrs), and therefor does not affect what you are burning during a workout. You're BMR is not exactly relevant to answering this question. This is probably more what you're looking for. "You burn fewer calories when you exercise in cold weather than you do when it's hot. The hotter it is, the more extra work your heart has to do to prevent you from overheating. More than 70 percent of the energy produced by your muscles during exercise is lost as heat. So the harder you exercise, the hotter your muscles become. In hot weather, not only must your heart pump extra blood to bring oxygen to your muscles, it must also pump hot blood from your heated muscles to your skin where heat can be dissipated. On the other hand, in cold weather, your heart only has to pump blood to your muscles and very little extra blood to your skin to dissipate heat. Your muscles produce so much heat during exercise that your body does not need to produce more heat to keep you warm. So your heart works harder and you burn more calories in hot weather." Gabe Mirkin M.D. This is the link where I found the answer http://ezinearticles.com/?Do-You-Burn-More-Calories-in-Winter-or-Summer?&id=116807

Studies show that being in very hot or very cold temperatures requires the body to burn more calories, yes. A sauna also helps the body sweat significantly more than many forms of exercise. And heat itself helps loosen muscles and dissipate tightness and pain. It also helps circulation and provides relaxation. It's good for you. An infrared sauna is easier to handle, for longer, than the traditional saunas, which can mean people get more out of it. To avoid dehydration and kidney problems, people need 8 ounces of juice or mineral water before going in the sauna, plus another 8 ounces for each 1/2 hour in the sauna (once you get out). .... People should start w/15 minutes a day and work up to an hour, but not more. Overexercise is also not good. So for people who want to add to their calories being burned by an existing exercise program, OR build up their cardiovascular strength before starting a more rigorous exercise program, the sauna can be a great way to do it.

Studies show that being in very hot or very cold temperatures requires the body to burn more calories, yes. A sauna also helps the body sweat significantly more than many forms of exercise. And heat itself helps loosen muscles and dissipate tightness and pain. It also helps circulation and provides relaxation. It's good for you. An infrared sauna is easier to handle, for longer, than the traditional saunas, which can mean people get more out of it. To avoid dehydration and kidney problems, people need 8 ounces of juice or mineral water before going in the sauna, plus another 8 ounces for each 1/2 hour in the sauna (once you get out). .... People should start w/15 minutes a day and work up to an hour, but not more. Overexercise is also not good. So for people who want to add to their calories being burned by an existing exercise program, OR build up their cardiovascular strength before starting a more rigorous exercise program, the sauna can be a great way to do it.

I have looked into this too and although you burn fewer calories for the same activity in cold weather compared to hot weather the number of calories burned during relaxation is higher in cold weather because your body has to produce more heat to warm itself.