Does sweating release toxins?

After practicing yoga in normal temperatures for years, I recently attended a heated yoga class (heated quite hot: 95 to 100 degrees!). The experience left me dizzy, nauseous, and completely enervated. Afterwards, I expressed my concern to the teacher, asking why the studio needed to be so hot. She "explained" that by sweating, supposedly the body releases "toxins" and that my nausea and dizziness must indicate that I need to "detox." Personally, I think I was suffering from heat exhaustion. I've heard this silly explanation more than once, as many people seem to believe toxins are released through sweat. But is that true??? And — next question — doesn't exerting oneself in extremely hot temperatures seem like a recipe for dehydration? Are their any benefits that make it worthwhile, or is all this heated yoga just nonsense?


Does exercising on an empty stomach maximize fat burning?

I have recently learned that in order to burn fat as a fuel, your body requires carbohydrate. Up until this point I had been doing cardio training first thing in the morning on an empty stomach, as I had read that this is optimum for fat burning. However, now I have a small carbohydrate snack before I train in order to prevent my body using lean muscle tissue as a fuel. Today I have again read in another book that training on an empty stomach first thing in the morning burns the most fat. I am a little confused over the best thing to do! I train with weights twice a week and do cardio three times per week. I do want to maintain my lean muscle, but am looking to reduce my body fat.


Is my hair addicted to dandruff shampoos?

I have dandruff that responds well to over-the-counter shampoo. Ergo, I have been using the stuff almost exclusively for ten years. No brand in particular, sometimes zinc pyrithione (the blue stuff!), sometimes coal tar (the smelly brown stuff!). Anytime I switch to non-dandruff shampoo for like three to four days straight, I get my dandruff back. I worry that I might be addicted to dandruff shampoo. Should I worry?


What can I do to take care of my very oily hair and skin?

Ever since high school, I've had very oily hair and skin, but it became worse in college. Now I'm in my mid-twenties and have to shampoo my hair about 10 times each day to get it clean. Then by evening it's already oily again. This isn't my scalp trying to moisturize itself after being over cleaned, because I've tried not washing it completely and it's even oilier the next day.

Are there any special shampoos or medications that help reduce oily skin? I've tried some facial products from my dermatologist, but they haven't reduced the oil production. This is an embarrassing problem and limits the overnight activities I can do, like camping or staying with friends.


How often should I wash my hair?

The last time I was at the hair cutting salon, the person who washed my hair asked me if I washed my hair everyday. I said I did, and she said she could tell. I'm not sure what she meant by this, but please tell me how she could determine this, and what is the best overall practice for washing hair in terms of frequency. I'm interested in the health of my hair as well as the health of my scalp. Thanks for you help!