Sites like bodybuilding.com, Men's Fitness, Muscle & Strength, etc. still use terms such as "endomorph, "ectomorph" and "mesomorph". These so-called "somatotypes" were invented by the psychologist (and possible eugenicist) William Herbert Sheldon, Jr. Sheldon tied each of the bodytypes to certain personality traits, and his research has been discredited time and again as racist hogwash.

That being said, if so many of these respected fitness websites make reference to the somatotypes, is it because we've since proven there to be some accuracy to the distinct body types without the connection to personality? Or is this just a case of bad science being hard to wash away.

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    IMO, these are merely handy terms used by the websites without the implications of the original theory. Those who are genetically predisposed to being thin may be called ectomorphic instead of «people who tend to be thin naturally». It does not mean that people who say that also imply that the naturally thin person is also an anxious introverted intellectual. Or at least it appears so. Nov 14, 2014 at 10:20
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    Also, people love their excuses. "Oh, well I'm an endomorph, I can't get thin." "I'm an ectomorph, I can't get muscular."
    – JohnP
    Nov 14, 2014 at 15:11
  • @MischaArefiev that's begging the question of whether being "genetically predisposed to being thin" is possible
    – TonyArra
    Nov 14, 2014 at 15:33
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    @JohnP: there was a study recently that basically said that people who are not predisposed to being good at painting never become good at painting. Sometimes those excuses are valid. Even if you prove that body type is a social construct, people who are predisposed to being lazy will invent new ones :) Nov 14, 2014 at 15:45
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    @JohnP: it says that there is no proven link between body type and personal traits and intellect. I don't see where it says that body metabolism is proven to not be hereditary. Nov 14, 2014 at 16:49

3 Answers 3


Or is this just a case of bad science being hard to wash away.


There is no evidence of a somatotypes being caused by genetics in anyway. All of Sheldon's initial work on Somatotypes was related to psychology, which has since been debunked.

Since then, there has been no study done that gives a genetic correlation between a somatotype and body type.

Somatotypes are broadly used to say you are either fat, muscular or tall and thin.

Taller "Ectomorphic" people will naturally have trouble gaining the visual "bulkiness" of a shorter person due to higher calorie requirements and phsyiological differences in muscle. A taller person will have longer limbs, causing muscles to be longer making them appear "smaller".

The difference between Mesomorphic and Endomorphic comes down to body fat alone, and shedding excess fat can make someone who looks Endomorphic become Mesomorphic, based on appearance alone.

Why does the theory of Somatotype exist? Because people are lazy and like excuses

Fitness magazines/websites aren't in the business of making you fit, they are in the business of selling magazines/getting page-views so they can sell ad space. You getting fit is a by-product. Somatotypes give a convenient way to say "being chubby" isn't your fault, its your genetics so that you don't feel bad and stop buying/clicking.

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    Care to provide a link to a study? Preferably the one that found near-zero correlation between metabolism characteristics of parents and kids. Nov 14, 2014 at 15:46
  • You will find interesting discussion on this over on skeptics.stackexchange.com/q/19943/619 - importantly, it looks like there is evidence. I'm just focusing on the physical aspects, not the behavioural/personality ones.
    – Rory Alsop
    Nov 17, 2014 at 11:45
  • @RoryAlsop That question shows a link between body composition and personality, but offers no evidence that someone is "born mesomorphic".
    – user2861
    Nov 18, 2014 at 5:34
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    On my reading it suggests there are links between genetics and somatotypes, but no link to personality.
    – Rory Alsop
    Nov 18, 2014 at 8:35
  • @LegoStormtroopr Ignoring Sheldon's psychobabble and nudie pics, there are numerous studies that describe racial / genetic differences in bone density, limb length, lung / chest volume, body fat...... essentially all the variables that go into the Heath-Carter variant of the Somatotype methodology, which is an accepted scientific taxonomy eg. ncbi.nlm.nih.gov/pubmed/12196029 or press.endocrine.org/doi/abs/10.1210/jcem.83.5.4765
    – arober11
    Jun 16, 2015 at 15:38

There are no distinct body types and they are for the most part not connected to personality, with the exception of eating habits. People with high apetite will have an easier time putting on both fat and muscle. So one could say that endomorphs tend to like food more than ectomorphs I guess, assuming that the higher body weight is caused to a larger degree by apetite than by any difference in metabolism.

In fact, thin people typically overestimate the amount of calories they eat, while large people underestimate it, leading to the wide-spread myth of high or low metabolism being common.

As I said above, there are no distinct body types, but there are body types! Some people are born shot putters and some are born marathon runners. Genes do have an impact, but they don't make people cluster around these three types.


Somatotyping is essentially stereotyping (assigning an “empirical generalization” to an individual), as to whether this is valid / acceptable is another matter, but have a read of: All Stereotypes Are True, Except... I: What Are Stereotypes?

Anyway Somatotyping is taught, in English Schools and Universities, as a valid means to assess an individual's suitability / potential to become an elite performer in certain sports eg. basketball, gymnastics, distance running, rowing, wrestler.... Even the BBC covers the technique.

It's generally packaged up / taught under the Applied Anatomy or Kinanthropometry banners, and is backed by a number of studies that have shown a correlation between certain physical characteristics and achievement at an elite level in certain sports e.g.

There are also papers that show the methodology is not applicable to the selection of athletes in multi discipline events, or where random and / or environmental variables play a significant role eg.

In the last few decades Heath-Carter and Rempel have formularised the categorization process, and the technique has been used is a number of anthropometric studies eg.

  • Study on the adult physique with the Heath-Carter anthropometric somatotype in the Han of Xi'an, China.
  • Somatotype characteristics of female patients with type 2 diabetes mellitus.
  • Somatotype characteristics of male patients with type 2 diabetes mellitus.

There have also been numerous studies that show a neurobiological effect / benefit of physical exercise, to quote wikipedia:

People who regularly participate in aerobic exercise have greater scores on neuropsychological function and performance tests. Examples of aerobic exercise that produce these changes are running, jogging, brisk walking, swimming, and cycling. Exercise intensity and duration are positively correlated with the release of neurotrophic factors and the magnitude of nearly all forms of exercise-induced behavioral and neural plasticity; consequently, more pronounced improvements in measures of neuropsychological performance are observed in endurance athletes as compared to recreational athletes or sedentary individuals. Aerobic exercise is also a potent long-term antidepressant and a short-term euphoriant; consequently, consistent exercise has also been shown to produce general improvements in mood and self-esteem in all individuals.

which would appear to accidentally / partially support Sheldon original work.

For a bit of background and a list of a dozen papers that support the technique, in sports selection, see the BrianMac site.

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    This does not seem to answer the question, which is a "why"-question.
    – Alec
    Jun 2, 2015 at 6:26
  • @Alec the link I've just added to the top of the answer / the following quote hopefully answers the WHY element of the question: 'What people call “stereotypes” are what scientists call “empirical generalizations,” and they are the foundation of scientific theory.' How those generalizations were proposed and their validity is a far more interesting question.
    – arober11
    Aug 19, 2015 at 14:03

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