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Gynoid fat distribution

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Gynoid fat refers to the body fat that forms around the hips, breasts and thighs.[1] Gynoid fat in women is used to provide nourishment for offspring, and is often referred to as 'reproductive fat'. This is because it contains long-chain polyunsaturated fatty acids (PUFAs), which are important in the development of foetuses.[2] However, it is also regarded as a physically attractive feature and serves additionally as an indication towards a woman's reproductive potential for mates.[3]

Characteristics

Composition

Gynoid fat is mainly composed of long-chain polyunsaturated fatty acids.[2] It is proposed that babies which are breast-fed are more likely to have increased cognitive capabilities due to these fatty acids being present in the breast milk, as they have been suggested to aid early brain development in foetuses and newborns.[4] The most notable fatty acids found in human breast milk are Docosahexaenoic acid and Arachidonic acid, which have been shown to play crucial roles in the healthy formation and functions of neurons.[5]

Location

Gynoid fat contributes toward the Female body shape that girls begin to develop at puberty; it is stored in the breasts and the hips, thighs and bottom.[6] This process is modulated by estrogen, the female sex hormone, causing the female form to store higher levels of fat than the male form, which is affected primarily by Testosterone.[7]

Difference from android fat

See Android fat distribution

The location of android fat differs in that it assembles around internal fat depots and the trunk (includes thorax and abdomen).[2] Android fat has more of a survival role and is utilised by the body as an energy source when energy supplies are low, in contrast to the reproductive functions of gynoid fat.[8]

Reproductive function

Gynoid fat is primarily a store of energy to be utilised in the nurturing of offspring, both to provide adequate energy resources during pregnancy and for the infant during the stage in which they are breastfeeding.[9] When there are insufficient energy resources in the environment or health issues which require energy to combat a woman's storage of gynoid fat is likely to be reduced. Therefore, ancestrally, a female with high levels of gynoid fat would be signalling to males that they are in an optimal state for reproduction and nurturing of offspring. This can be seen in the fact that a female's Waist–hip ratio is at its optimal minimum during times of peak fertility - late adolescence and early adulthood, before increasing later in life.[10]

As a female's capacity for reproduction comes to an end, the fat distribution within the female body begins a transition from the gynoid type to more of an android type distribution. This is evidenced by the percentages of android fat being far higher in post-menopausal than pre-menopausal women.[11][12]

Sex differences

Sexual dimorphism

The differences in gynoid fat between men and women can be seen in the typical "hourglass" figure of a woman, compared to the inverted triangle which is typical of the male figure. Women commonly have a higher body fat percentage than men and the deposition of fat in particular areas is thought to be controlled by sex hormones and GH.[13]

The hormone estrogen inhibits fat placement in the abdominal region of the body, and stimulates fat placement in the glutofemoral areas (the buttocks and hips). Certain hormonal imbalances can affect the fat distributions of both men and women. Women suffering from polycystic ovary syndrome, characterised by low estrogen, display more male type fat distributions such as a higher waist-to-hip ratio. Conversely, men who are treated with estrogen to offset testosterone related diseases such as prostate cancer may find a reduction in their waist-to-hip ratio.[14]

Sexual dimorphism in distribution of gynoid fat was thought to emerge around puberty but has now been found to exist earlier than this.[15]

Relevance in sexuality

Sexual signalling: Waist-to-hip ratio

Gynoid fat bodily distribution is measured as the waist-to-hip ratio (WHR), whereby if a woman has a lower waist-to-hip ratio it is seen as more favourable.[16] Studies have found correlations between WHR and Intelligence quotient (IQ) levels. It was found not only that women with a lower WHR (which signals higher levels of gynoid fat) had higher levels of IQ, but also that low WHR in mothers was correlated with higher IQ levels in their children.[17]

Android fat distribution is also related to WHR, but is the opposite to gynoid fat. Instead, android fat is deposited in the waist, breasts, buttocks and thighs, but can give an unattractive appearance, as it gives women a ‘T-shaped” body and is more lumpy.[18] The ratio of a woman’s gynoid to android fat is used to measure her WHR, whereby the lower the WHR, the higher gynoid to android fat ratio, which is perceived as more attractive for women. As women with higher levels of gynoid fat distribution are seen as more attractive, this enables them to access highly desirable male mates.[19] WHR is related to various markers of health and fertility, for example a high WHR is correlated with: a low estrogen/testosterone ratio (this means that a woman has more of a 'T-shaped' body which is seen as less healthy and attractive); a high ratio is also correlated to circulatory system problems such as heart attacks and strokes; more disease (e.g. cancer); and is a general sign of increased age and hence lower fertility, therefore supporting the adaptive significance of an attractive WHR.[20] This advantage of being more fertile has been supported by various studies, for example artificial insemination studies involving sperm donors, where the best predictor of success is a low WHR.[21] Similarly, a high WHR has been associated with impairment in the pregnancy rate of IVF (in vitro fertilisation) embryo transfer women due to the higher levels of android fat distribution.[22] Further studies have also found that oestrogen replacement in women lowers the WHR in pre- and post-menopausal women, and that this is because oestrogen replacement maintains gynoid fat distribution in the body.[23]

A low WHR increases the mate value of a woman by communicating many of the following attractive features: the absence of pregnancy (and therefore high mate value); youth;[18] general health; high oestrogen; high fertility and thus high capacity to produce intelligent offspring.[24] Further research has supported the idea of these features being more attractive by showing that females with lower WHR, slimmer figures and larger breasts were rated as being more desirable for long-term relationships. On the other hand, a larger figure with large hips was perceived to be less youthful, less physically attractive, and thus less desirable for long-term relationships.[25] However, the more attractive females (those with low WHR) were not only more desirable for long-term relationships, but for more casual short-term relationships also. This is because the low WHR (and thus attractiveness) signals higher quality genes for which males want to associate their offspring with in order to ensure reproductive success.[26]

Sexual signalling: Breasts

Both android and gynoid fat are found in female breast tissue.[27] Females develop breasts around puberty and breasts with less android fat and more gynoid fat are firmer and more attractive to men. Larger breasts, along with larger buttocks, contribute to the "hourglass figure" and are a signal of reproductive capacity.[28] The proportion of gynoid fat is a good predictor of female reproductive capability, such as conception probability and likelihood of successful pregnancy.[29] As humans evolved and became bipedal, other areas of signalling such as genital swelling became less visible and consequently other forms of sexual signalling had to develop.[30] Being able to store an optimum amount of gynoid fat requires a female to have access to resources such as food and therefore is an honest signal of having sufficient energy resources to successfully reproduce.[31]

Cosmetic surgery

However, not all women have the most optimal distribution of gynoid fat, hence there are now trends of cosmetic surgery, such as liposuction or breast enhancement procedures which give the illusion of attractive gynoid fat, and can create a lower waist-to-hip ratio (WHR) or larger breasts than some are able to achieve naturally.[32] Other examples include micrograft surgery,[33] which involves the deposition of adipose tissue, previously taken from the waist, into the buttocks. This achieves again, the lowered WHR and the 'pear-shaped' or 'hourglass' feminine form; all deemed attractive features.[25] Cosmetic surgery represents a vast body of evidence supporting the hypothesis that people are evolutionarily programmed to be attracted to health features.

Ornamentation

A biological ornament is sexual signal of attractiveness involved in the process of sexual selection, and functions as an honest signal of quality.[34] Sexual ornamentation of females involves more attractive levels of gynoid fat, meaning bigger breasts and buttocks and a low WHR these all signal health, fertility, genetic quality, and thus attractiveness.

Ornamentation is important in female intrasexual competition, which involves female-female competition for potential mates and their associated resources. Since the function of such ornamentation is to compete for male resources, females with a lower WHR are favoured.[35] Ornamentation also plays a key role in male mate choice, where again, females with a low WHR are favoured as they are more attractive.[36] The benefits of attractive ornamentation are gaining resources from males. Attractive ornamentation allows more access to highly desirable males with material resources (e.g. food) and higher mating success. Further benefits of attractive ornamentation are seen in the protection of a female and her offspring. This can be from sexually coercive males, or from raiding males who are looking to capture females.[37]

Cultural differences

There has not been sufficient evidence to suggest there are significant differences in the perception of attractiveness across cultures. Females considered the most attractive are all within the normal weight range with a low waist-to-hip ratio (WHR), regardless of fluctuations in BMI, and this finding can be seen as consistent across Indonesian, Chinese, White and African-American young men and women.[33][38] Psychologists have argued that evolutionary selection processes have facilitated this relationship between WHR and female attractiveness, which has resulted in a consensus that seems to transcend cultural boundaries.[39]

Health issues

Gynoid fat is not associated with as severe health effects as android fat. Gynoid fat is a lower risk factor for cardiovascular disease than android fat.[40] However excess body fat in the main source of estrogen in the body and therefore particularly high levels of gynoid fat can increase the risk of breast cancer developing.[41]

See Also

References

  1. ^ Brody, Tom (1999). Nutritional Biochemistry, p. 385. Academic Press, London. ISBN 0121348369.
  2. ^ a b c Thornhill, Randy (2008). The Evolutionary Biology of Human Female Sexuality, p. 113. Oxford University Press, USA. ISBN 0199712484.
  3. ^ Singh, Devendra (1994-01-01). "Is thin really beautiful and good? Relationship between waist-to-hip ratio (WHR) and female attractiveness". Personality and Individual Differences. 16 (1): 123–132. doi:10.1016/0191-8869(94)90116-3.
  4. ^ Agostoni, C; Marangoni, F; Bernardo, L; Lammardo, Am; Galli, C; Riva, E (1999-09-01). "Long-chain polyunsaturated fatty acids in human milk". Acta Pædiatrica. 88: 68–71. doi:10.1111/j.1651-2227.1999.tb01303.x. ISSN 1651-2227.
  5. ^ "The Role of DHA and ARA in Infant Nutrition and Neurodevelopmental Outcomes". www.todaysdietitian.com. Retrieved 2016-03-17.
  6. ^ Kirchengast, S., Gruber, D., Sator, M., Knogler, W., & Huber, J. (1997). The fat distribution index-a new possibility to quantify sex specific fat patterning in females. Homo, 48(3), 285-295.
  7. ^ "Tanita - Women & Body Fat". 2009-02-16. Archived from the original on February 16, 2009. Retrieved 2016-03-17. {{cite web}}: Unknown parameter |deadurl= ignored (|url-status= suggested) (help)
  8. ^ Lancaster, J. B. (1986). Human adolescence and reproduction: An evolutionary perspective. School-Age Pregnancy and Parenthood. Hawthorne, NY: Aldine de Gruyter, 17-39.
  9. ^ Plowman, Sharon & Smith, Denise (2007). Exercise Physiology for Health, Fitness, and Performance, p. 218. Lippincott Williams & Wilkins. ISBN 0781784069
  10. ^ Thornhill, Randy (2008). The Evolutionary Biology of Human Female Sexuality, p. 117. Oxford University Press, USA. ISBN 0199712484
  11. ^ Ley, C. J.; Lees, B.; Stevenson, J. C. (1992-05-01). "Sex- and menopause-associated changes in body-fat distribution". The American Journal of Clinical Nutrition. 55 (5): 950–954. ISSN 0002-9165. PMID 1570802.
  12. ^ Kirchengast, S.; Gruber, D.; Sator, M.; Hartmann, B.; Knogler, W.; Huber, J. (1997-01-01). "Menopause-associated differences in female fat patterning estimated by dual-energy X-ray absorptiometry". Annals of Human Biology. 24 (1): 45–54. doi:10.1080/03014469700004762. ISSN 0301-4460.
  13. ^ Jürimäe, J., Hills, A. P., & Jürimäe, T. Cytokines, Growth Mediators and Physical Activity in Children during Puberty. Karger Medical and Scientific Publishers, 2010, p. 7.
  14. ^ Johansen, Magnus D. Exercise and Health Research. Nova Publishers, 2007, p. 3.
  15. ^ Goran, M. I. & Sothern, M. S. Handbook of Pediatric Obesity: Etiology, Pathophysiology, and Prevention. CRC Press, 2005, p. 42.
  16. ^ Singh, Devendra. "Adaptive significance of female physical attractiveness: Role of waist-to-hip ratio". Journal of Personality and Social Psychology. 65 (2): 293–307. doi:10.1037/0022-3514.65.2.293.
  17. ^ Lassek, W. D., & Gaulin, S. J. (2008). Waist-hip ratio and cognitive ability: is gluteofemoral fat a privileged store of neurodevelopmental resources? Evolution and Human Behavior, 29(1), 26-34.
  18. ^ a b Singh, D. (1994). Is thin really beautiful and good? Relationship between waist-to-hip ratio (WHR) and female attractiveness. Personality and Individual Differences, 16(1), 123-132.
  19. ^ Singh, D. (1993). Body shape and women’s attractiveness. Human Nature, 4(3), 297-321.
  20. ^ Singh, D. (1993). Adaptive significance of female physical attractiveness: role of waist-to-hip ratio. Journal of personality and social psychology, 65(2), 293.
  21. ^ Zaadstra, B. M., Seidell, J. C., Van Noord, P., te Velde, E. R., Habbema, J. D., Vrieswijk, B., & Karbaat, J. (1993). Fat and female fecundity: prospective study of effect of body fat distribution on conception rates. Bmj, 306(6876), 484-487.
  22. ^ Wass, P., Waldenström, U., Rössner, S., & Hellberg, D. (1997). An android body fat distribution in females impairs the pregnancy rate of in-vitro fertilization-embryo transfer. Human Reproduction, 12(9), 2057-2060.
  23. ^ Genazzani, A. R., & Gambacciani, M. (2006). Effect of climacteric transition and hormone replacement therapy on body weight and body fat distribution. Gynecological endocrinology, 22(3), 145-150.
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  25. ^ a b Singh, D., & Young, R. K. (1995). Body weight, waist-to-hip ratio, breasts, and hips: Role in judgments of female attractiveness and desirability for relationships. Ethology and Sociobiology, 16(6), 483-507.
  26. ^ Douglas, W. Y., & Shepard, G. H. (1998). Is beauty in the eye of the beholder?. Nature, 396(6709), 321-322.
  27. ^ Campbell, Anne (2013-05-16). A Mind Of Her Own: The evolutionary psychology of women. OUP Oxford. ISBN 9780191647024.
  28. ^ Parker, Sue Taylor; Jaffe, Karin Enstam (2008-06-13). Darwin's Legacy: Scenarios in Human Evolution. AltaMira Press. ISBN 9781461647669.
  29. ^ Thornhill, Randy; Gangestad, Steven W. (2008-09-25). The Evolutionary Biology of Human Female Sexuality. Oxford University Press. ISBN 9780199712489.
  30. ^ Mealey, Linda (2000-04-13). Sex Differences: Developmental and Evolutionary Strategies. Academic Press. ISBN 9780080541136.
  31. ^ Mealey, Linda (2000-04-13). Sex Differences: Developmental and Evolutionary Strategies. Academic Press. ISBN 9780080541136.
  32. ^ Singh, D., & Randall, P. K. (2007). Beauty is in the eye of the plastic surgeon: Waist–hip ratio (WHR) and women’s attractiveness. Personality and Individual Differences, 43(2), 329-340.
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  35. ^ Amundsen, T. (2000). Why are female birds ornamented?. Trends in Ecology & Evolution, 15(4), 149-155.
  36. ^ Singh, D., & Young, R. K. (1995). Body weight, waist-to-hip ratio, breasts, and hips: Role in judgments of female attractiveness and desirability for relationships. Ethology and Sociobiology, 16(6), 483-507.
  37. ^ Saino, N., Ferrari, R. P., Martinelli, R., Romano, M., Rubolini, D., & Møller, A. P. (2002). Early maternal effects mediated by immunity depend on sexual ornamentation of the male partner. Proceedings of the Royal Society of London B: Biological Sciences, 269(1495), 1005-1009.
  38. ^ Singh, Devendra; Luis, Suwardi (1995-03-01). "Ethnic and gender consensus for the effect of waist-to-hip ratio on judgment of women's attractiveness". Human Nature. 6 (1): 51–65. doi:10.1007/BF02734135. ISSN 1045-6767.
  39. ^ "Cross-cultural consensus for waist–hip ratio and women's attractiveness - Evolution and Human Behavior". www.ehbonline.org. Retrieved 2016-03-21.
  40. ^ Shilstone, Mackie (2004-12-03). The Fat-Burning Bible: 28 Days of Foods, Supplements, and Workouts that Help You Lose Weight. John Wiley & Sons. ISBN 9780471655299.
  41. ^ Smith, Merril D. (2014-09-08). Cultural Encyclopedia of the Breast. Rowman & Littlefield. ISBN 9780759123328.
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