The waist is the part of the Human abdomen between the rib cage and hips. On people with slim bodies, the waist is the narrowest part of the torso.
The waistline refers to the horizontal line where the waist is narrowest, or to the general appearance of the waist.
Because of this and because the waist is often synonymous with the stomach, one can become confused as to the exact location of the waist. Another confusing factor is that the waistline differs on different people. A study
showed that self-reported measurements as opposed to measurement done by a technician, underestimated waist circumference and this underestimation increased with increased body size. In the study, waist circumference measured at the level of the umbilicus was larger than that measured at the natural waist. To locate the natural waistline, one need simply stand upright and then tilt over to the side keeping the legs and hips straight. Where the torso creases is the natural waistline.
Strictly, the waist circumference is measured at a level midway between the lowest rib
and the iliac crest
An alternative approximation of high relevance in anthropometry is Small of the Back (SOB) + 2cm.
In anthropometrics, the location of the waist (height) can be predicted as 72% of the neck height, or between the iliac crest (60% of total height) and the lowest palpable rib (64% of total height).
The waist-hip ratio equals the waist circumference divided by the hip circumference. Practically, however, the waist is usually measured at the smallest circumference of the natural waist, usually just above the belly button.
[ Waist To Hip Calculator at University of Maryland Medical System. Retrieved Dec 2010] In case the waist is convex rather than concave, such as is the case in pregnancy and obesity, the waist may be measured at a vertical level 1 inch above the navel. [ ] It is important to note that variables such as posture significantly influence the measurement of the waist, and therefore any measurements for a group need to maintain a constant posture between the subjects.
The size of a person's waist or waist circumference, indicates abdominal obesity. Excess abdominal fat is a risk factor for developing heart disease and other obesity related diseases. The National Heart, Lung, and Blood Institute (NHLBI)
classifies the risk of obesity-related diseases as high if men have a waist circumference greater than and women have a waist circumference greater than .
A study published in the European Heart Journal April 2007
showed that waist circumference and waist-hip ratio were predictors of cardiovascular events.
Waist–hip ratio is the ratio of the circumference of the waist to that of the
. It measures the proportion by which fat
is distributed around the torso
Waist–hip ratios of 0.7 for women and 0.9 for men have been shown to correlate strongly with general health and fertility. Colloquially this shape is compared to the hourglass shape.
[Female Body Characteristics Related to Bra Fit - Page 20, 2007]
Society and culture
In modern clothing the region referred to as the waist is considerably below the waist as defined anatomically.
With the advent of pants and skirts that do not require support from above, the clothing waist moved down to a position where the body starts to expand to form the buttocks and a support is therefore available. However, the waist region remains a highly important measurement and anthropometric landmark in garment construction.
Jewellery, such as a belly chain, may be worn around either the clothing or anatomical waist.
Waist reduction and training
Waist reduction or waist training refer to the act of wearing a corset
or other constricting garment to reduce or alter the waistline. The four
may be permanently compressed or moved by such garments. A girdle
may also be used to alter the appearance of the waist.
Waist reduction may be used simply to reduce the width of the waist. This change can be permanent or temporary.
Waist training may be used to achieve a certain permanent waist shape, such as a pipe-stem waist.
Definition: "middle part of the body," also "part of a garment fitted for the waist, portion of a garment that covers the waist" (but, due to fashion styles, often above or below it), probably from Old English *wæst "growth," hence, "where the body grows," from Proto-Germanic *wahs-tu- (cognates: Old English wæstm, Old Norse vöxtr, Swedish växt, Old High German wahst "growth, increase," Gothic wahstus "stature," Old English weaxan "to grow".