Ectomorph, mesomorph and endomorph – you’ve probably heard of these three body types, or somatotypes, but what do they really mean?

In the 1940s it was an American named William Sheldon who first proposed this theory of constitutional psychology. His theory suggested human physique could be categorised into these three categories:

  • Ectomorph

People who fit into the category of an ectomorph tend to have long limbs and a thin bone structure. It’s supposed to be hard for ectomorphs for put on either muscle or fat, resulting in a generally slim appearance.

  • Mesomorph

Mesomorphs have a much thicker bone structure and greater levels of fat. In particular mesomorphs are said to build muscle more easily – often leading to a small waist and wider upper torso.

  • Endomorph

Endomorphs are people we would describe as overweight, they have stored fat and find it difficult to burn this fat, or build noticeable amounts of muscle.

So does your somatotype matter, or are we pre-programmed to only fit one body type?

Well this is a theory, and more importantly it’s a psychological theory. While each somatotype does exist, where constitutional psychology is contested is the claim that we all belong to one somatotype and that doesn’t change.

The truth is that your metabolism is completely unrelated to bone structure, and can change regardless of your somatotype. In fact, there are countless real-life transformations of people who appear to possess all the characteristics for each somatotype, just at different times.

Your levels of fat and muscle can, and will, change over your life, and it is quite possible that somebody can be overweight at one time and be underweight at another.

Where somatotypes can’t be changed is in bone structure. Genetics determine your bone structure, and people will naturally have slightly thicker or thinner bones and joints.

The extremist arguments view this as the ‘somatotype myth’, and disregard any argument that we as humans have our body shapes pre-determined and can’t change that. On the other hand, supporters of constitutional psychology firmly believe that for some of us it is genuinely harder to put on weight and build muscle.

The problem with categorising yourself into a particular somatotype is that at that moment when you decide you are a particular body type, you’ve already established a mental barrier to progress.

for example, if you tell yourself you are an ectomorph then you will find excuses for not building muscle effectively. Similarly if you tell yourself you are an endomorph you may justify being overweight, and be less concerned with burning fat.

Essentially, we as humans fit into one of the somatotypes at any one point. Right now, as you read this blog, your body type could be classed as ectomorph, mesomorph or endomorph.

But say you read this again in 6 months – at that point you could be reading it with a completely different body shape.

Any professional working around fitness will tell you that they don’t care if you consider yourself to be anyone of the body types, and while you are unique, the principals of building muscle and burning fat apply to us all.

Just remember – don’t let anything serve as a barrier to your progress. Goals are there to be reached, and if your goals are reasonable you will reach them providing you put in the required amount of hard work and dedication.


Ollie Lawrence