Hormones are chemicals which act at specific sites in the body, called target tissues, and instigate change at those sites. A hormone that has gained popularity lately is leptin, due mostly to its activity as an "anti-obesity" hormone. Leptin has many roles in a body, not solely related to weight loss, which have a variety of effects on health.
Anti-obesity Effect
Leptin is a key player in suppressing fat cell creation and promoting fat metabolism. Leptin also acts on the brain to enhance feelings of fullness after eating. This is a key element in preventing obesity and in losing weight as it reduces the urge to over-eat.
Wasting Syndromes
Because it increases metabolism, leptin appears to promote wasting syndromes (excessive weight loss) caused by infections associated with AIDS. Other appetite-suppressing chemicals triggered by leptin compound weight loss in these patients.
Reproductive Impact
Research suggests that leptin stimulates the onset of puberty by activating hormones of the reproductive system. Reproductive hormones assist in the maturation of reproductive organs in both males and females. Leptin activity is elevated in females during puberty, which is thought to be due to intricate changes that must occur in the female reproductive system in order for a woman to become pregnant and sustain a pregnancy.
Colon Cancer
Preliminary studies on leptin relative to cancer suggest that severity of colon cancer and the migration (movement) of colon cancer cells may be caused by elevated leptin concentration in the body.
Brain Development
Though not well understood, leptin is believed to play a role in brain health and function. A 2008 University of Miami study found that a child participant with a genetic leptin deficiency was developmentally slow compared to children of the same age. The research concluded that leptin replacement over the course of 2 years may have resulted in brain growth and development (see Resources below).
Obese persons have reduced brain tissue in certain areas of the brain. The leptin increase associated with obesity has been fingered as a possible culprit in this tissue loss. A study published in the February 2007 issue of "Neuroscience Letter" (Nicola Pannacciullia, author) found that, in obese individuals with elevated fasting leptin levels, there were reduced amounts of gray matter in the areas of the brain that affect reward, taste and behavioral processing.
Cardiovascular Effects
Metabolic syndrome describes a condition in which persons suffer from a cluster of diseases including high blood pressure, type II diabetes, abnormalities in blood fats, and waistline obesity. Increased leptin level complicates this syndrome, increasing risk of stroke and sudden fatal heart attack.
Enlarged Prostate
Leptin has been a suspect in the development of benign prostatic hyperplasia (BPH), also called enlarged prostate. This condition occurs with age and interferes with urination. Evidence from several large studies suggests, however, that factors other than leptin---but related to obesity---are responsible for increased risk of this condition.
References
- Medicinski pregled; Macut D et al.; Leptin and human reproduction; 1998
- International Journal of Cancer; Jaffe T.; Leptin promotes motility and invasiveness in human colon cancer cells by activating multiple signal-transduction pathways; 2001
- Prostate; Shenk, J M, et al.; Serum adiponectin, C-peptide and leptin and risk of symptomatic benign prostatic hyperplasia: results from the Prostate Cancer Prevention Trial; 2009
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