Waist-hip ratio or Waist-to-hip ratio (WHR) 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. The concept and significance of WHR was first theorized by evolutionary psychologist Dr. Devendra Singh at the University of Texas at Austin in 1993. 
A WHR of 0.7 for women and 0.9 for men have been shown to correlate strongly with general health and fertility. Women within the 0.7 range have optimal levels of estrogen and are less susceptible to major diseases such as diabetes, cardiovascular disorders and ovarian cancers. Men with WHRs around 0.9, similarly, have been shown to be more healthy and fertile with less prostate cancer and testicular cancer.
WHR is a better measure of assessing a person’s risk of heart attack than body mass index (BMI). If obesity is redefined using WHR instead of BMI, the proportion of people categorized as at risk of heart attack worldwide increases threefold.
Other studies have not found a correlation between WHR and increased cardiovascular risk or body fat distribution.
Scientists have discovered that the waist-hip ratio (WHR) is a significant factor in judging female attractiveness. Women with a 0.7 WHR (waist circumference that is 70% of the hip circumference) are usually rated as more attractive by men from European cultures. Such diverse beauty icons as Marilyn Monroe, Sophia Loren, Kelly Brook, Alessandra Ambrosio and even the Venus de Milo all have ratios around 0.7, even though they have different weights. In other cultures, preferences appear to vary according to some studies, ranging from 0.6 in China, to 0.8 or 0.9 in parts of South America and Africa, and divergent preferences based on ethnicity, rather than nationality, have also been noted. In Mauritania, being fat seems to be the ideal, so much so that it is causing an obesity problem.
Important: In the studies referenced above, only frontal WHR preferences differed significantly among racial and cultural groups. When actual (circumferential) measurements were made, the preferred WHR tended toward the expected value of 0.7 universally. The apparent differences are most likely due to the different body fat storage patterns in different population groups. For example, women of African descent tend to store their fat in their buttocks more than women of other groups. Therefore, their WHR as viewed from the front may appear to be much greater than when viewed from the side. The inverse may be true of women of East Asian ancestry. Therefore, African men appear to value a woman's small WHR in profile and an Asian man may place more value on an exaggerated frontal WHR compared to European men. Thus, in studies which only present frontal drawings or photographs to male subjects, non-Europeans will seem to have different WHR preferences, when in fact they may not in actual terms.
Women with a low waist-hip ratio have been shown in studies to be smarter and have smarter offspring. Using data from the US National Center for Health Statistics, William Lassek at the University of Pittsburgh in Pennsylvania and Steven Gaulin of the University of California, Santa Barbara, found a child's performance in cognition tests was linked to their mother's waist-hip ratio, a proxy for how much fat she stores on her hips.
Children whose mothers had wide hips and a low waist-hip ratio scored highest, leading Lassek and Gaulin to suggest that fetuses benefit from hip fat that contains polyunsaturated fatty acids critical for the development of the fetus's brain.
Many methods have been used to artificially alter a person's apparent WHR. These include corsets used to reduce the waist size and hip and buttock padding used by some transgendered people to increase the apparent size of the hips and buttocks.
^ "Men's preferences for women's profile waist-to-hip ratio in two societies.". Retrieved on 2007-09-01.
^ American Journal of Clinical Nutrition August 12,2006
^Obesity and the risk of myocardial infarction in 27,000 participants from 52 countries: a case-control study. The Lancet, Nov. 5th 2005
^A comparative evaluation of waist circumference, waist-to-hip ratio and body mass index as indicators of cardiovascular risk factors. The Canadian Heart Health Surveys.
^Waist measure and waist-to-hip ratio and identification of clinical conditions of cardiovascular risk: multicentric study in type 2 diabetes mellitus patients
^Superiority of skinfold measurements and waist over waist-to-hip ratio for determination of body fat distribution in a population-based cohort of Caucasian Dutch adults.
^ Singh, Devendra; Young, Robert K. (2001-Jun-27). "Body Weight, Waist-to-Hip Ratio, Breasts, and Hips: Role in Judgments of Female Attractiveness and Desirability for Relationships". Ethology and Sociobiology16: 483-507. Retrieved on 2007-11-23.
^ Fisher, M.L.; Voracek M. (June 2006). "The shape of beauty: determinants of female physical attractiveness.". J Cosmet Dermatol5 (2): 190-4. PMID 17173598. Retrieved on 2007-08-04.
^ Dixson, B.J.; Dixson A.F., Li B., Anderson M.J. (January 2007). "Studies of human physique and sexual attractiveness: sexual preferences of men and women in China.". Am J Hum Biol19 (1): 88-95. PMID 17160976. Retrieved on 2007-08-04.
^ Marlowe, F.; Wetsman, A. (2001). "Preferred waist-to-hip ratio and ecology". Personality and Individual Differences30 (3): 481-489. Retrieved on 2007-08-04.
^ Marlowe, F.W.; Apicella, C.L. and Reed, D. (2005). "Men’s Preferences for Women’s Profile Waist-Hip-Ratio in Two Societies". Evolution and Human Behavior26: 458-468. Retrieved on 2007-08-04.
^ Dixson, B.J.; Dixson A.F., Morgan B., Anderson M.J. (June 2007). "Human physique and sexual attractiveness: sexual preferences of men and women in Bakossiland, Cameroon". Arch Sex Behav36 (3): 369-75. PMID 17136587. Retrieved on 2007-08-04.
^ Freedman, R.E.; Carter M.M., Sbrocco T., Gray JJ. (Aug. 2007). "Do men hold African-American and Caucasian women to different standards of beauty?". Eat Behav8 (3): 319-33. PMID 17606230. Retrieved on 2007-08-04.
^ Freedman, R.E.; Carter M.M., Sbrocco T., Gray J.J. (July 2004). "Ethnic differences in preferences for female weight and waist-to-hip ratio: a comparison of African-American and White American college and community samples". Eat Behav.5 (3): 191-8. PMID 15135331. Retrieved on 2007-08-04.
^ ab Lassek, W.; Gaulin S. (July 2007). "Waist-hip ratio and cognitive ability: is gluteofemoral fat a privileged store of neurodevelopmental resources?". Evolution and Human Behavior. PMID S1090-5138(07)00073-6. Retrieved on 2007-10-04.