The human waist
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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.
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, 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, 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) is an indicator of abdominal obesity. 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 (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 102 cm (40 in) and women have a waist circumference greater than 88 cm (35 in). 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 function, therefore capturing the neurobehavioral pathophysiology of obesity.
Waist–hip ratio is the ratio of the circumference of the waist to that of the hips. 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. This shape is compared to the hourglass shape of women.
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.
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 ribs 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".
- ^ Bigaard, Janne; Spanggaard, Iben; Thomsen, Birthe Lykke; Overvad, Kim (1 September 2005). "Self-Reported and Technician-Measured Waist Circumferences Differ in Middle-Aged Men and Women". The Journal of Nutrition. 135 (9): 2263–2270. doi:10.1093/jn/135.9.2263. PMID 16140909.
- ^ Waist To Hip Calculator at University of Maryland Medical System. Retrieved Dec 2010
- ^ Brown JE, Potter JD, Jacobs DR, et al. (January 1996). "Maternal waist-to-hip ratio as a predictor of newborn size: Results of the Diana Project". Epidemiology. 7 (1): 62–6. doi:10.1097/00001648-199601000-00011. JSTOR 3702758. PMID 8664403. S2CID 24471765.
- ^ Han, T.; Van Leer, E.; Seidell, J.; Lean, M. (1995). "Waist circumference action levels in the identification of cardiovascular risk factors: prevalence study in a random sample". BMJ (Clinical Research Ed.). 311 (7017): 1401–1405. doi:10.1136/bmj.311.7017.1401. PMC 2544423. PMID 8520275. 
- ^ a b c Gill, Simeon; Parker, Christopher J. (2014). The True Height of the Waist: Explorations of Automated Body Scanner Waist Definitions of the TC2 scanner. Proc. Of 5th Int. Conf. On 3D Body Scanning Technologies. pp. 55–65. doi:10.15221/14.055. ISBN 9783033047631. Retrieved 1 May 2018.
- ^ Gill, Simeon; Parker, Christopher J. (2017). "Scan posture definition and hip girth measurement: the impact on clothing design and body scanning". Ergonomics. 60 (8): 1123–1136. doi:10.1080/00140139.2016.1251621. PMID 27764997. S2CID 23758581.
- ^ Lawrence de Koning; Merchant, AT; Pogue, J; Anand, SS (2007). "Waist circumference and waist-to-hip ratio as predictors of cardiovascular events: meta-regression analysis of prospective studies". European Heart Journal. 28 (7): 850–6. doi:10.1093/eurheartj/ehm026. PMID 17403720.
- ^ Obesity Education Initiative, Aim for a Healthy Weight
- ^ Farruggia MC, Van Kooten MJ, Perszyk E, Burke, MV, Scheinost, D, Constable, TC, Small, DM (August 2020). "Identification of a brain fingerprint for overweight and obesity". Physiology & Behavior. 222: 112940. doi:10.1016/j.physbeh.2020.112940. PMC 7321926. PMID 32417645.
- ^ Female Body Characteristics Related to Bra Fit - Page 20, 2007
- ^ Gill, Simeon; Parker, Christopher J. (2016). "Scan posture definition and hip girth measurement: the impact on clothing design and body scanning". Ergonomics. 60 (8): 1123–1136. doi:10.1080/00140139.2016.1251621. PMID 27764997. S2CID 23758581.
- ^ "waist - Origin and meaning of waist by Online Etymology Dictionary". www.etymonline.com.
- "Waist" . Encyclopædia Britannica (11th ed.). 1911.
- Measured average height, weight, and waist circumference for adults ages 20 years and over (U.S.)