mass movement

or mass wasting

Bulk movements of soil and rock debris down slopes, or the sinking of confined areas of the Earth's ground surface. The term mass wasting refers only to gravity-driven processes that move large masses of earthen material from one place to another. The term mass movement includes the sinking of confined areas.

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Wasting could also mean unefficient and/or uneffective consumption. See waste.

In medical circles, wasting refers to the process by which a debilitating disease causes muscle and fat tissue to "waste" away. Wasting is sometimes referred to as "acute malnutrition" because it is believed that episodes of wasting have a short duration, in contrast to stunting, which is regarded as chronic malnutrition.

Causes

Wasting can be caused by an extremely low energy intake (e.g., caused by famine), nutrient losses due to infection, or a combination of low intake and high loss. Infections associated with wasting include tuberculosis, chronic diarrhea, and AIDS. The mechanism may involve cachectin - also called tumor necrosis factor, a macrophage-secreted cytokine. Caretakers and health providers can sometimes contribute to wasting if the patient is placed on an improper diet. Voluntary weight loss and eating disorders are excluded as causes of wasting.

Classification

• Children: Weight-for-height (WFH). In infants under 24 months, recumbent (supine) length is used. WFH as % of median reference value is calculated this way:

$mathrm\{WFH\}\; =\; frac\{mbox\{weight\; of\; a\; given\; child\}\}\{mbox\{median\; weight\; for\; a\; given\; child\; of\; that\; height\}\}\; times\; 100$

Cutoff points may vary, but <80% (close to -2 Z-score) is often used.

• Adults:
• Body Mass Index (BMI) is the quotient between weight and height squared (kg/m²). An individual with a BMI < 18.5 is regarded as a case of wasting.
• Percent of body weight lost (At Tufts, an unintentional loss of 6% or more in 6 months is regarded as wasting)

See also

• Atrophy
• Cachexia
• Weight loss

External links

• http://www.cdc.gov/ncidod/EID/vol10no6/03-1082.htm
• http://www.tufts.edu/med/nutrition-infection/hiv/health_weight_loss.html
• http://www.annalsnyas.org/cgi/content/abstract/587/1/325
• Scientists find key to "wasting syndrome"