Human body shape is a complex phenomenon with sophisticated detail and function. The general shape or figure of a person is defined mainly by the molding of skeletal structures, as well as the distribution of muscles and fat.[1] Skeletal structure grows and changes only up to the point at which a human reaches adulthood and remains essentially the same for the rest of their life. Growth is usually completed between the ages of 13 and 18, at which time the epiphyseal plates of long bones close, allowing no further growth (see Human skeleton).[2]
Many aspects of body shape vary with gender and the female body shape especially has a complicated cultural history. The science of measuring and assessing body shape is called anthropometry.
Physiology
During puberty, differentiation of the male and female body occurs for the purpose of reproduction. In adult humans, muscle mass may change due to exercise, and fat distribution may change due to hormone fluctuations. Inherited genes play a large part in the development of body shape.
Due to the action of testosterone, males may develop these facial-bone features during puberty:
A more prominent brow bone (bone across the centre of the forehead from around the middle of eyebrow across to the middle of the other) and a larger nose bone.[3]
Because females have around 1/4 the amount of testosterone of a male, the testosterone-dependent features do not develop to the same extent, and female faces are generally more similar to those of pre-pubertal children.
Skeletal structure
Comparison between a male (left) and a female pelvis (right). Females generally have wider hips relative to males in the same population. (Images not to scale.)
Skeletal structure frames the overall shape of the body and does not alter much after maturity. Males are, on average, taller, but body shape may be analyzed after normalizing with respect to height. The length of each bone is constant, but the joint angle will change as the bone moves.[6]
Widening of the hip bones occurs as part of the female pubertal process,[7] and estrogens (the predominant sex hormones in females) cause a widening of the pelvis as a part of sexual differentiation. Hence females generally have wider hips, permitting childbirth. Because the female pelvis is flatter, more rounded and proportionally larger, the head of the fetus may pass during childbirth.[8] The sacrum in females is shorter and wider, and also directed more toward the rear (see image).[9] This sometimes affects their walking style, resulting in hip sway.[10] The upper limb in females have an outward angulation (carrying angle) at elbow level to accommodate the wider pelvis. After puberty, hips are generally wider than shoulders. However, not all females adhere to this stereotypical pattern of secondary sex characteristics.[11] Males and females generally have the same hormones, but blood concentrations and site sensitivity differs between males and females. Males produce primarily testosterone with small amounts of estrogen and progesterone, while women produce primarily estrogen and progesterone and small amounts of testosterone.[12]
The rear view of a naked adult man with pronounced hip width and large buttocks, both typically associated with male figure. Male Musculature Study - photograph by Albert Londe, Paul Marie Louis Pierre Richer (MET, 2012.59)The rear view of a naked adult woman with pronounced hip width and large buttocks, both typically associated with female physique
Body shape is affected by body fat distribution, which is correlated to current levels of sex hormones.[1] Unlike bone structure, muscles and fat distribution may change from time to time, depending on food habits, exercises and hormone levels.
Estrogen causes fat to be stored in the buttocks, thighs, and hips in females.[13] When females reach menopause and the estrogen produced by ovaries declines, fat migrates from their buttocks, hips and thighs to their waists.[14] Later fat is stored in the belly, similar to males.[15] Thus females generally have relatively narrow waists and large buttocks, and this along with wide hips make for a wider hip section and a lower waist–hip ratio compared to males.[16]
Testosterone helps build and maintain muscles through exercise. On average, men have around 5-20 times more testosterone than women and naturally and biologically males gain more muscle mass and size than women.[20] However, women can also build muscle mass by increasing the testosterone level naturally.[21] Prominent muscles of the body include the latissimus dorsi and trapezius in the back, pectoral muscles and rectus abdominis ("abs") in the chest and stomach, as well as biceps and triceps in the arms and gluteus maximus, quadriceps and hamstrings in the thighs.[22]
Breasts
Females have breasts due to functional mammary glands, which develop in puberty from the influence of various hormones such as thyroxine, cortisol, progesterone, estrogen, insulin, prolactin, and human growth hormone.[23] Mammary glands do not contain muscle tissue. The shape of female breasts is affected by age, genetic factors, and body weight. Women's breasts tend to grow larger after menopause, due to increase in fatty deposits caused by decreasing levels of estrogen. The loss of elasticity from connective tissue associated with menopause also causes sagging.[24]
Weight
Being overweight or underweight affects the human body's shape as well as posture and walking style.[citation needed] This is measured using Body Mass Index (BMI). Depending on the BMI, a body may be referred to as underweight, normal, overweight, or obese. A person with a BMI below 18.5 is classed as underweight, between 18.5 and 24.9 is ideal, above 24.9 is overweight and a BMI of 30 or higher is defined as obese.[25]
Body posture and gait
Body shape has effects on body posture[26] and gait, and has a major role in physical attraction. This is because a body's shape implies an individual's hormone levels during puberty, which implies fertility, and it also indicates current levels of sex hormones.[1] A pleasing shape also implies good health and fitness of the body. Posture also affects body shape as different postures significantly alter body measurements, which thus can alter a body's shape.[26][27]
Different forms of exercises are practiced for the fitness of the body and also for health. It is a common belief that targeted exercise reduces fat in specific parts of the body —for example, that exercising muscles around the belly reduces fat in the belly. This, however, is now proven to be a misconception; these exercises may change body shape by improving muscle tone but any fat reduction is not specific to the locale. Spot reduction exercises are not useful unless you plan proper exercise regime to lose overall calories. But exercising reduces fat throughout the body, and where fat is stored depends on hormones. Liposuction is surgery commonly used in developed societies to remove fat from the body.
The general body shapes of female and male bodies both have significant social and cultural symbolism. Physical attractiveness is closely associated with traits that are considered typical of either sex.[34] The body mass index (BMI), waist-to-hip ratio, and especially waist-to-chest ratio in men have been shown in studies to rank as overall more desirable to women. To be deemed to have an "athletic built"/build[35] is usually a reference to wide shoulders, a muscular upper body and well-developed upper-arm muscles which are all traits closely associated with masculinity, similarly to other specifics of the male sex, like beards. These traits are seen more sexually attractive to women and also associated with higher intelligence, good leadership qualities and better health.[36]
Terminology
Classifications of female body sizes are mainly based on the circumference of the bust–waist–hip (BWH), as in 36–24–36 (inches) respectively. In this case, the waist–hip ratio is 24/36 = 0.67. Many terms or classifications are used to describe body shape types:
V shape: Males tend to have proportionally smaller buttocks, bigger chests and wider shoulders, wider latissimus dorsi and a small waist which makes for a V-shape of the torso.
Hourglass shape: The female body is significantly narrower in the waist both in front view and profile view. The waist is narrower than the chest region due to the breasts, and narrower than the hip region due to the width of the buttocks, which results in an hourglass shape.
Apple: The stomach region is wider than the hip section, mainly in males.
Pear or spoon or bell: The hip section is wider than the upper body, mainly in females.[citation needed]
Rectangle or straight or banana: The hip, waist, and shoulder sections are relatively similar.
See also
Body image – Aesthetic perception of one's own body
^However, one expert suggested that her "almost matronly representation" was meant to convey an "impressive appearance" rather than "ideal female beauty".[33]
^Hodges-Simeon, Carolyn R.; Sobraske, Katherine N. Hanson; Samore, Theodore (14 April 2016). "Facial Width-To-Height Ratio (fWHR) Is Not Associated with Adolescent Testosterone Levels". PLOS ONE. 11 (4): e0153083. Bibcode:2016PLoSO..1153083H. doi:10.1371/journal.pone.0153083. ISSN1932-6203. PMC4831733. PMID27078636. "Specifically, facial width/lower face height gets smaller (i.e., the lower face grows more than the width of the face), cheekbone prominence gets smaller (i.e., the width of the face at the mouth—a measure of relative jaw width—grows more than the width of the cheekbones), and lower face height/full face height gets larger (i.e., facial growth is focused in the lower face) as male adolescents develop. These results are consistent with the craniofacial literature that documents pronounced growth in the male mandible under the influence of exogenous T [51] and during puberty [83–85]. Similarly, the association between T and these mandible-inclusive facial ratios accords with Lefevre et al. [16], who found significant sexual dimorphism in these three ratios, but no adult sex difference in fWHR." See Table 1 and Figure 2 for cheekbone relation to testosterone levels.
^Saeki T, Furukawa T, Shimizu Y (1997). "Dynamic clothing simulation based on skeletal motion of the human body". International Journal of Clothing Science and Technology. 9 (3): 256–263. doi:10.1108/09556229710168414. ISSN0955-6222.
^ ab"Reproductive Anatomy and Physiology". The Harriet and Robert Heilbrunn Department of Population and Family Health. Columbia University Mailman School of Public Health. Retrieved 2011-10-09. Secondary sexual characteristics occur as part of the pubertal process
^Lauretta, R; Sansone, M; Sansone, A (2018). "Gender in Endocrine Diseases: Role of Sex Gonadal Hormones". International Journal of Endocrinology. 2018: 4847376. doi:10.1155/2018/4847376. PMC6215564. PMID30420884. Generally, females and males have the same hormones (i.e., estrogens, progesterone, and testosterone), but their production sites, their blood concentrations, and their interactions with different organs, systems, and apparatus are different [29]. Males produce predominantly testosterone from the testes in a relatively constant daily amount according to a circadian profile. Small amounts of estrogens and progesterone are produced by the testes and the adrenal glands or are produced in the peripheral tissues, such as adipose tissue or liver, by the conversion of other precursor hormones [30]. In contrast, females mainly produce estrogens and progesterone from the ovaries in a cyclical pattern, while a small amount of testosterone (T) is produced by the ovaries and adrenal glands.
^The SuRF Report 2(PDF). The Surveillance of Risk Factors Report Series (SuRF). World Health Organization. 2005. p. 22. Archived(PDF) from the original on 2022-10-09.
^"People: Just Deserts". Time. May 28, 1945. Archived from the original on August 11, 2009. Retrieved August 5, 2011. ... "the most perfect all-over beauty of all time." Runner-up: the Venus de Milo.
^CBS News Staff (August 5, 2011). "Venus". CBS News. Retrieved August 5, 2011. The classical vision of beauty exemplified in Greek art, such as the 2nd century B.C. Venus de Milo (a.k.a. Aphrodite of Milos), was an ideal carried through millennia, laying the basis for much of Western art's depictions of the human form.
^Swami V (2006). "The Influence of Body Weight and Shape in Determining Female and Male Physical Attractiveness". In Kindes MV (ed.). Body Image: New Research. New York: Nova Publishers. pp. 36–51. ISBN978-1-60021-059-4.
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