Ultimate Guide to Body Types | Endomorph, Mesomorph, Ectomorph Calculator
In this article, we will dig a bit deeper into the differences in body types, take a more detailed look at their bone structure, and dive into fat and muscle distribution.
One scientist in the 1940s, William Sheldon, PhD, MD, attempted to group individuals based on bone structure and weight distribution.  His studies yielded three primary body types called somatotypes - ectomorph, mesomorph, and endomorph. Each somatotype was said to have unique characteristics that may influence an individual's preferred form of physical activity based on their strengths and weaknesses.
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Dr. Sheldon further expanded on this concept of body types in his 1954 book entitled Atlas of Men. He offered a three-digit scaling system to determine someone's somatotype. Each digit, based on predefined criteria, ranges from 1 to 7 where a pure ectomorph is 1-1-7, a pure mesomorph is 1-7-1, and pure endomorph is 7-1-1. 
He likely designed this system after receiving a critique that someone may exhibit characteristics of more than one somatotype.
The 3 Primary Body Types - Somatotypes
Now that we've discussed the history of somatotypes, let's examine the three pure somatotypes - the ectomorph, the mesomorph, and the endomorph.
The ectomorph body type is your stereotypical self-proclaimed hardgainer. An ectomorph has a hard time adding mass to its long and lean build, but naturally carries less fat than other somatotypes.
In general, ectomorphs have a high forehead, receding chin, narrow shoulders, hips, chest, and abdomen, as well as thin arms and legs.  From the personality standpoint Dr. Sheldon describes ectomorphs as intellectual, introverted, emotionally restrained individuals who crave isolation and solitude due to their tense, anxious, and secretive nature. 
Ectomorph body types typically don't excel at power and strength sports since they have a hard time gaining muscle mass, but they do excel in endurance sports and gymnastics.  Being able to naturally maintain very low levels of body fat allows ectomorphs to keep a high strength to bodyweight ratio as well as undergo less physical stress during repetitive movement long-duration activities such as running and cycling compared to mesomorphs or endomorphs.
One study of 63 men ages 18-40 years found that ectomorphs had the greatest ratio of carbon dioxide produced to oxygen consumed in one breath as well as the lowest peak oxygen uptake during peak exercise.  Because of their smaller surface area, ectomorphs can regulate their body temperature and breathing more efficiently than mesomorphs and endomorphs; a trait that is particularly important in aerobic endurance activities.
Famous athletes with an ectomorph somatotype include Frank Zane, Ulisses William Jr., Michael Phelps, Lance Armstrong, Kevin Garnett, Manny Pacquiao, Usain Bolt, and Bruce Lee.
The mesomorph body type is your stereotypical ideal bodybuilding physique. Mesomorphs are athletic, strong, not underweight or overweight, and can increase and decrease their bodyweight weight with minimal effort. 
In general, mesomorph body types have a wedge-shaped body, cubical head, broad shoulders, muscular arms and legs, narrow hips, minimal fat, and are narrow when viewing their side profile.  From the personality standpoint Dr. Sheldon describes mesomorphs as rugged and thick-skin individuals who are extroverted, aggressive, direct, dominant, courageous, and prone towards physical activity and taking risks. 
Mesomorphs have the ideal physique for physical activities requiring strength, agility and speed such as football, wrestling, and Olympic lifting. They are the genetically gifted individuals that can easily maintain low body fat, increase or decrease weight based on the requirement of their preferred physical activity, and develop all muscle groups evenly.  These individuals are the ideal athlete because they not only have a have a medium bone structure and height but they typically excel at both cardiovascular and resistance training activities.
Famous athletes with a mesomorph somatotype include Arnold Schwarzenegger, Jay Cutler, Anna Kournikova, Terrell Owens, Bo Jackson, and Jackie Chan.
The stereotypical endomorph body type gains weight easily so they naturally carry significant amounts of both mass muscle and fat mass, but they're not necessarily always overweight. In general, endomorphs have a pear-shaped body, short arms and legs, a round head, wide hips and shoulders, significant amounts of fat on the body (especially upper arms and thighs), and are wide when viewing their side profile. 
From the personality standpoint, Dr. Sheldon describes endomorphs as sociable, easy-going, slow-to-react, easily complacent, comfort-seeking individuals that enjoy food, people, and affection.  Endomorphs do not excel in activities requiring high levels of agility, speed, or weight-bearing aerobic activity like running but do excel at pure strength activities like powerlifting, rugby, and playing the lineman position in football.
Endomorph body types can quickly gain fat and lose conditioning if they decrease or discontinue physical activity. However, they typically have a large lung capacity which is beneficial in non-weight-bearing aerobic activities like rowing and they can increase their muscle mass much quicker than ectomorphs. 
Famous athletes with an endomorph somatotype include Benedikt Magnusson, Konstantin Konstantinovs, Lee Priest, Vince Wilfork, and Ndamukong Suh.
Somatotype CalculatorNow that we've discussed the characteristics of the three primary body types, the somatotype calculator below provides you with your somatotype blend. Although rare, you may be a pure ectomorph, mesomorph, or endomorph. Most individuals are a blend of these three somatotypes.
Ectomorph body type tendencies:
- Lean and thin
- Narrow hips, chest and shoulders
- Do not have much muscle OR fat
- Long legs and arms
- Higher forehead and thinner face
Mesomorph body type tendencies:
- Naturally muscular
- Narrow hips and wide shoulders
- Strong legs and arms
- Modest amount of body fat
Endomorph body type tendencies:
- Larger frame
- More body fat than most
- Narrow shoulders and wider hips
- Slim ankles and wrists
Limitations of Using Somatotype ClassificationOn the surface, the somatotype classification system sounds logical and useful. However, there are a few glaring limitations.
Firstly and most importantly it's extremely rare to find someone who is a pure version of one of the three primary somatotypes. Most individuals exhibit characteristics of two or even all three somatotypes. One study of 524 men and 250 women found that 95% of subjects fell within five somatotype categories - endomorphic mesomorphs, mesomorph-endomorphs, mesomorphic endomorphs, balanced mesomorphs, and ectomorphic mesomorphs. 
Additional classifications include ectomorphic endomorphs that have pear-shaped bodies with small upper bodies and high fat accumulation in the hips and thighs as well as endomorphic ectomorphs that have apple-shaped bodies with small lower bodies and high fat accumulation in the midsection.  As you can see, with the exception of a balanced mesomorph, none of those aforementioned classifications are pure somatotypes. This study also found men were most likely to be endomorphic mesomorphs and women were most likely to be mesomorph-endomorphs. 
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Another study of men and women found that the average distribution of somatotypes is 51.6% endomorphic mesomorphs, 17.1% mesomorph-endomorphs, 16.7% mesomorphic endomorphs, 6.1% balanced mesomorphs, and 3.0% ectomorphic mesomorphs.  65% of men in this population were endomorphic mesomorphs and those 40+ years old shifted towards more of a mesomorph somatotype.  This indicates that your somatotype classification is not static and can shift over time.
On average mesomorphic endomorphs typically have a higher lean body weight compared to endomorph-ectomorphs and endomorphic ectomorphs.  Mesomorphs typically carry a significant amount of muscle with minimal fat mass and when paired with the large frame of an endomorph, this is the recipe for a large and muscular individual.
Furthermore, the average lean body weight to weight ratio, lean body weight to total adipose tissue weight ratio, and total body water to weight ratio were lowest for mesomorphic endomorphs.  This further indicates that mesomorphic endomorphs carry a significant amount of lean mass and minimal fat mass.
Secondly, Dr. Sheldon's attempted correlation between somatotype and personality is exceptionally inaccurate. I know plenty of outgoing ectomorphs, non-aggressive mesomorphs, and introverted endomorphs. Personality and somatotype are mutually exclusive characteristics.
Furthermore, playing into the somatotype classifications encourages individuals to victimize their situation and avoid activities they may enjoy in fear that their body type isn't built for such activities. For example, I have broad shoulders, short legs, long arms, and do not have a narrow side profile, but that didn't stop me from running cross country in high school. Instead of victimizing my body type I embarked on a proper training regimen which resulted in my 5k PR of 18:12 which works out to a 5:51 mile pace.
In conclusion, the somatotype classification system is an interesting yet outdated tool for grouping individuals based on their bone structure and weight distribution. Somatotypes have no correlation to personality types but somatotypes can be a useful tool for examining common or ideal body types for specific sports.
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4) Kamlesh, M.L. (2011). "Ch. 15: Personality and Sport § Sheldon's Constitutional Typology". Psychology in Physical Education and Sport. Pinnacle Technology. ISBN 9781618202482.
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