The waist is the part of the

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...

between the

rib cage The rib cage, as an enclosure that comprises the ribs, vertebral column and sternum in the thorax of most vertebrates, protects vital organs such as the heart, lungs and great vessels. The sternum, together known as the thoracic cage, is a sem ...

and

hips In vertebrate anatomy, hip (or "coxa"Latin ''coxa'' was used by Celsus in the sense "hip", but by Pliny the Elder in the sense "hip bone" (Diab, p 77) in medical terminology) refers to either an anatomical region or a joint. The hip region ...

. On people with slim bodies, the waist is the narrowest part of the

torso The torso or trunk is an anatomical term for the central part, or the core, of the body of many animals (including humans), from which the head, neck, limbs, tail and other appendages extend. The tetrapod torso — including that of a huma ...

. ''Waistline'' refers to the horizontal line where the waist is narrowest, or to the general appearance of the waist.

Structure

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.

Waist measurement

The waist is usually measured at the smallest circumference of the natural waist, usually just above the belly button. Where the waist is convex rather than concave, as in pregnancy and obesity, the waist may be measured at a vertical level 1 inch above the navel. Strictly, the waist circumference is measured at a level midway between the lowest palpable rib and the

iliac crest The crest of the ilium (or iliac crest) is the superior border of the wing of ilium and the superiolateral margin of the greater pelvis. Structure The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the poster ...

, respectively typically 60% and 64% of total height. It can be predicted as 72% of the neck height; an alternative approximation, very relevant in

anthropometry Anthropometry () refers to the measurement of the human individual. An early tool of physical anthropology, it has been used for identification, for the purposes of understanding human physical variation, in paleoanthropology and in various at ...

, is Small of the Back (SOB) + 2cm. 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. Waist size (waist

circumference In geometry, the circumference (from Latin ''circumferens'', meaning "carrying around") is the perimeter of a circle or ellipse. That is, the circumference would be the arc length of the circle, as if it were opened up and straightened out t ...

) is an indicator of abdominal

obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's ...

. Excess abdominal fat is a risk factor for developing heart disease and other obesity related diseases. A study published in the ''European Heart Journal'' April 2007 showed that waist circumference and

waist–hip ratio The waist–hip ratio or waist-to-hip ratio (WHR) is the dimensionless ratio of the circumference of the waist to that of the hips. This is calculated as waist measurement divided by hip measurement (). For example, a person with a 30″ ( ...

(defined as waist circumference divided by hip circumference) were predictors of cardiovascular events. 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 . Further, whether waist circumference or BMI is a better predictor of adverse health outcomes is debatable. For example, those who lift weights may have high BMI but are at relatively low risk for cardiovascular consequences. For these people, waist circumference may be a better indicator of overall health. Some research suggests waist circumference can be predicted from

brain A brain is an organ that serves as the center of the nervous system in all vertebrate and most invertebrate animals. It is located in the head, usually close to the sensory organs for senses such as vision. It is the most complex organ in a ve ...

function, therefore capturing the neurobehavioral pathophysiology of obesity.

Waist–hip ratio

Waist–hip ratio is the ratio of the circumference of the waist to that of the hips. It measures the proportion by which

fat In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food. The term often refers specifically to triglycerides (triple est ...

is distributed around the

. Waist–hip ratios of 0.7 for women and 0.9 for men have been shown to correlate strongly with general health and

fertility Fertility is the capability to produce offspring through reproduction following the onset of sexual maturity. The fertility rate is the average number of children born by a female during her lifetime and is quantified demographically. Fertili ...

. This shape is compared to the hourglass shape of women.

Society and culture

Fashion

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 Jewellery ( UK) or jewelry (U.S.) consists of decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes. From a wester ...

, such as a

belly chain Belly may refer to: Anatomy * The abdomen, the part of the body between the pelvis and the thorax; or the stomach ** A beer belly, an overhang of fat above the waist, presumed to be caused by regular beer drinking ** Belly dance * The fleshy, cen ...

, 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

floating rib The rib cage, as an enclosure that comprises the ribs, vertebral column and sternum in the thorax of most vertebrates, protects vital organs such as the heart, lungs and great vessels. The sternum, together known as the thoracic cage, is a semi-r ...

s may be permanently compressed or moved by such garments. A

girdle A belt, especially if a cord or rope, is called a girdle if it is worn as part of Christian liturgical vestments, or in certain historical, literary or sports contexts. Girdles are used to close a cassock in Christian denominations, including th ...

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.

History

Etymology

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".

References

External links

*
Measured average height, weight, and waist circumference for adults ages 20 years and over (U.S.)
{{Human regional anatomy Abdomen Secondary sexual characteristics