Sweat glands (apocrine glands) under the arms and in the groin secrete a substance that is the major non-food/drink related cause of Body Odor . This substance, which contains protein, carbohydrates, and lipids, often secreted by a surge in sex hormones caused by tense moments or emotional stress, is quickly attacked by bacteria, causing odor. Also, today children are starting puberty much earlier, and this change in hormones may lead to Body Odor in children younger than previously. Estrogen dominance, often caused by petrochemical products, may trigger the earlier puberty. Drinking sodas out of plastic bottles is one of the leading causes of estrogen dominance.
Found here: http://www.health911.com/remedies/rem_bodyo.htm