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. 

There may be underlying causes of excessive sweating, such as low blood sugar, liver disease, diabetes, parasites, metabolic dysfunction, menopause, or emotional stress (anger, fear, excitement). Excessive sweat may be on the forehead, palms, soles of the feet or the underarms. See our Sweaty Hands section for some suggestions to help with this problem. 

Some other possible cause of body odor... 

Kidney disease 
Liver disease 
Fungal infections 
Refined sugar feeds bacteria and fungus on the skin