Emotion, stress, physical activity, a few minutes stuck in traffic in mid-summer and we're soaked! It's perfectly natural!
But if you're leaving perspiration stains first thing in the morning on a light dress or tank top, your "natural" may have a problem! 

If we talk in car terms, you could say that perspiring is our body's exhaust pipe. Perspiration is essential. It is first triggered by contact with heat, and allows our body to cool itself and maintain a constant temperature. Sweat cools the skin, and as blood comes in contact with it, it too is cooled, then circulated to regulate our body temperature.

Everyone has two to four million sweat glands, particularly active this time of year, that produce on average a liter of sweat per day (an athlete can lose up to two liters an hour!), which regulates our body temperature... though it's never been known to make us lose weight! After having lost so much water, your body needs to be rehydrated, and the needle on the scale will go back to where it was originally.

But what causes odor? 
The sweat secreted by our eccrine glands is naturally odorless - it's water containing a little salt. Unpleasant odors - mainly from the feet and underarms - comes from the combination of sweat and bacteria. This phenomenon is most noticeable in the underarms, because along with the genital region, this body zone is the seat of the apocrine glands or odor glands which animals use for sexual identification.