Body Shape and Size Notes
Body Shape & Size
Differences in body shape and size between individuals are due to independent assortment, genetic exchange (crossing over + recombination) during meiosis, and mutations. Individuals have no control over developmental determinants, genetic makeup, sex, and age. Factors with potential individual control include physical activity, diet, and environmental/social factors.
Body Types
Hourglass: Shoulders and hips in proportion, defined waist.
Round/Apple: Shoulders and hips in proportion, larger waistline/tummy.
Pear: Shoulders and waist smaller than hips and bottom.
Inverted Triangle: Shoulders larger than waist and bottom (swimmer shape).
Lean Column: Shoulders, hips, and waist in proportion and lean.
Rectangle: Shoulders in proportion to waist & hips, little waist definition.
Petite: Short in height (below 158cm).
Plus Size: Tall or larger, curvy with extra weight.
Somatotypes
Ectomorph: Thin build, difficulty gaining muscle/fat, fast metabolism, long limbs, narrow hips/clavicles, small joints, little muscle mass.
Mesomorph: Medium frame, long round muscles, narrow waist, quick response to strength training, thinner joints, wide clavicles.
Endomorph: Blocky build, easily gains muscle/fat, difficulty losing fat, wide hips, large bone structure, short thick arms/legs, thick rib cage, wide thick joints.
Population Variation
Body size and shape vary considerably among human populations. Mean body mass varies by 50% or more within sex. Height varies less (~10%) without geographic trend, while breadth varies more (~25%) with a latitudinal gradient. These differences may be due to physiological adaptive mechanisms.
Body Mass Index (BMI)
BMI is a measure of body fat based on height and weight. The formula is weight in kilograms divided by height in meters squared. For example: Weight = 68 kg, Height = 1.65 m, Calculation: .
Controlling Body Weight
Body weight can be controlled through diet and activity.
Changes in Body Proportions
At birth, the head is ~25% of body length; by adolescence, it's ~12.5%. Lower limbs grow fastest, making up 1/2 of total height. Upper limbs also grow faster than the trunk. During childhood, the body reshapes in proportion with changes in skeletal elements, fat distribution, and tissue maturation. Facial growth spurt occurs, and sinuses, mandible, and maxilla increase in size.
Sexual Dimorphism
Sexual dimorphism refers to differences in morphology between sexes. Human dimorphism includes sexual maturity, reproductive potential, general health, immune responses, and socio-sexuality. Facial dimorphism is influenced by sex hormones, with testosterone responsible for masculine features and estrogen-to-testosterone ratio for female features.
Dimorphism
Dimorphism is seen in limb proportion, joint angles (carrying angle at elbow, Q-angle at hip/knee), mass/weight, body fat % and distribution, and muscle mass. These changes occur during puberty due to growth spurts and hormonal influences.
Gender vs Sex
Gender is determined by society based on social and cultural differences. It's fluid and can vary. Sex is determined at birth by biological/physiological characteristics (XX/XY chromosomes), is binary, and remains constant.
Influences on Body Shape
Body shape changes throughout life depending on health, diet, age, sex, and environment. Genetic and environmental factors influence growth and development.