Steroids increase strength, mass and intensity levels. But steroids also cause acne, baldness, explosions of rage and high blood pressure. Most importantly, for men, steroids can causes testosterone levels to increase unnaturally, which, in turn reduces the body's ability to produce testosterone on its own.

Exercise is supposed to make your body healthier and make you feel better, but there are times when you finish a workout and feel clammy and nauseous. This is due to a number of factors, all of which can make fitness an unpleasant experience.

Your thyroid is a butterfly-shaped gland that sits near your vocal cords and produces the T3 and T4 hormones that control your metabolism. To make these hormones, your body uses iodine -- about 80 percent of the iodine you consume is used by your thyroid.

Testosterone is the primary androgen or male sex hormone; according to a 2001 "Endocrinology: An Integrated Approach" article, 95 percent of circulating testosterone is produced by the testes. Testosterone is also found in females but in much lesser concentrations.

The thyroid gland, located near the "Adam's apple" in your neck, has the vital function of controlling your body's metabolism. Diseases that impair the function of this gland can lead to depression, fatigue, weight gain, joint pain, hair loss, slowing of your metabolism and increased risk for heart disease.

Taking nutritional supplements is a common component of an adrenal fatigue recovery program. Among these supplements, bovine supplements -- consisting of extracts of dried adrenal glands derived from cows -- are ones that people with adrenal fatigue turn to quite commonly.

Estrogen is the female hormone that plays a role in various functions throughout the body. For women, estrogen helps maintain female features and is vital to your body's fertility. Estrogen also influences your mood and helps maintain your sexual organs.

Progesterone is a hormone that helps maintain the uterine lining in preparation for a pregnancy. Birth control pills, hormone replacement therapy and pills to regulate menstrual cycles often contain a synthetic form of progesterone.

The pituitary gland is a tiny gland located at the base of the brain. It is about the size of a pea and is located between the optic nerves. The pituitary gland is sometimes called the "master gland" because it controls hormone functions.

If you've considered buying over-the-counter bovine or herbal thyroid supplements, you might wonder how they differ from the synthetic thyroid hormones prescribed by physicians. Like synthetic thyroid therapy, bovine supplements replace hormones.

Human growth hormone, HGH, affects development and healing. Younger children with low growth hormone levels typically fail to reach normal height and weight. Older adults with HGH deficiency often have difficulty maintaining body weight and bone density.

Your thyroid gland produces hormones that affect your metabolism, weight, muscle strength, brain development, cholesterol levels and many other body functions. The two main thyroid hormones are triiodothyronine, or T3, and thyroxine, or T4.