I'm not fat, I'm just big boned

I have a t-shirt that says that.

To a certain extend, that is true. The built of a person depends on his skeletal structure, and also his muscular and fat and pretty much everything else to compose his stature.

The purpose of this write-up is to explain the categorisation of human body type, loosely classified into 3 somatotypes: endomorphs, ectomorphs and mesomorphs. Bear in mind that this categorisation does not scale a person into what is good or bad, but merely a description of types. Not any of the somatotypes are better or worse than another. Knowing your somatotype also helps you to make realistic target, especially when you workout to improve your appearance which will lead to a feeling of better well-being and health.

An endomorphic person is generally stocky, with a large round body, a short thick neck, short arms and legs, and with a tendency to store body fat. Generally, extreme endomorphs rate poorly on physical fitness tests and so make poor athletes in sports that require agility and speed. Still, it is possible that someone who is rated as an endomorph can modify their rating though diet and exercise to improve on physical performance and sports. With proper training, it is relatively easier for endomorphs to pack on muscle mass.

A mesomorphic person would be strongly built, with broad muscular chest and shoulders, muscular arms and legs, and relatively little body fat. An example of a mesomorphic person in the sporting world would be a typical weightlifter or shot putter. In general, mesomorphs rank high on strength, endurance, power and agility.

An ectomorphic person would generally be tall and thin, with a narrow body, thin arms and legs, little body fat and wiry muscles. They are the ones usually seen doing catwalks on fashion shows. An example of an ectomorphic person in the sporting world would be a typical long distance runner or basketball player. In general, ectomorphs rank high on endurance, flexibility and agility. 

It is important to remember that somatotyping is expressed as a sprectrum rather than clear-cut entities, and the majority of the population would have a mixed trait of the forms. The expression of somatotype gives a 3-digit code x-y-z, x being endomorphy rating, y for mesomorphy and z for ectomorphy. The rating ranges from 1 to 7, where 7 is the strongest expression of that particular attribute and 1 being weakest.

Though it is fairly unnecessary to know, the calculation of somatotype numbers takes into consideration these parameters, and computed using a formula.

1. Sex, Age
2. Height and Weight
3. Biceps and Calf Girth  
4. Femurs and Humerus Breadth 
5. Triceps, Biceps, Subscapular, Supraspinale, Abdominal, Thigh, Calf and Suprailiac Skinfolds
6. Chest Skinfold and Forearm Girth - for Males
7. Gluteal/Hip Girth - for Females
8. Waist circumference

The most important thing about somatotyping, I'd like to stress again, is just to know what type of stature we have, and that should guide us towards a more realistic and achievable goal-setting. And remember, there are no good or bad somatotype.

Health and fitness goals should instead, focus on parameters that matters such as our body muscle / fat composition, visceral fat rating, cardiovascular endurance, progressive strength training and physical fitness. A good gym would have it's own programme to keep track of these parameters and advice its members accordingly.

Next most important question is perhaps: What is the reason you exercise?

referrences:

http://www.topendsports.com/testing/somatotype.htm

http://somatotypecalculator.blogspot.com/