The Great Body Type Myth: Why Somatotypes Don’t Matter

Today, I want to talk to you about somatotypes.

You’ve got the ectomorph (thin and tall), the mesomorph (athletic and muscular), and the endomorph (usually characterized as short and fat).

There are plenty of training programs out there to hang their hat on the idea that somatotyping can help you “train smarter to maximize your potential.”

The theory is that knowing your somatotype will tell you what your ideal training and diet program should look like.

If you look like this, then your body type is this, and here’s how you should eat and train.

Personally, I think it’s nonsense, and I’ll explain why in a moment.

First, a little background.

History of Somatotypes

The terms ectomorph (thin and tall), mesomorph (athletic and muscular) and endomorph (usually characterized as short and fat) were coined in the 1940s by a guy called William Sheldon.

Sheldon believed that the size and shape of a person’s body were indicators of intelligence, temperament, moral worth, and even future achievement [1].

Here’s a video of the man himself talking about body types, if you’d like to watch.

Sheldon went on to describe three distinct somatotypes. Here are the definitions:

Ectomorph: Characterized by long and thin muscles/limbs and low fat storage; usually referred to as slim. Ectomorphs are not predisposed to store fat nor build muscle.

Mesomorph: Characterized by medium bones, solid torso, low fat levels, wide shoulders with a narrow waist; usually referred to as muscular. Mesomorphs are predisposed to build muscle but not store fat.

Endomorph: Characterized by increased fat storage, a wide waist and a large bone structure, usually referred to as fat, or chunky. Endomorphs are predisposed to storing fat.

Are Body Types Real?

Body types are certainly “real” in the sense that some people are naturally tall and thin, some are short and fat, while others are athletic and muscular. But that doesn’t mean you should use them to guide your decisions about what to eat and how to exercise.

While somatotyping works fine as a way of describing the way someone looks, it starts to fall apart when it comes to prescribing how they should train and eat.

That’s because somatotypes weren’t meant to help people decide what their diet and training program should look like.

Nor were they supposed to be used as a way to estimate your potential for muscle growth or fat loss.

What somatotyping was designed for and what some people are now using it for are two completely different things.

As trainer Alexander Juan Antonio Cortes points out in Digging Deeper into the Science of Somatotypes:

“Somatotyping relies upon subjective assessments of anatomy to infer subjective assessments of psychiatry. These assessments were never validated by any controlled experiments. They were purely the observations of Sheldon himself and his personal beliefs on body type for determining personality.

The big problem with somatotypes is that they’re just a description of your body at one point in time. And your body can change.

Take the example of a guy who looks like a typical ectomorph – skinny and weak. He starts lifting weights, and over a period of time puts on 20 or 30 pounds of muscle.

So what is he now? A mesomorph? Or is he still an ectomorph? Because he sure as hell doesn’t look like one.

Somatotypes and Muscle Growth

What’s more, you can’t always tell just by looking at someone how well their muscles will respond to training.

There are people with a low baseline level of muscle mass, but with the potential for rapid growth. Likewise, there are also people with a high baseline level of muscle mass who won’t see the same level of growth when they start lifting weights.

In one study, a group of untrained men lifted weights three times a week for 12 weeks. Muscle thickness was measured at the start of the study, and once again at the end.

When the researchers analyzed the results, they found that individuals who started out with less muscle posted the biggest gains in muscle size after 12 weeks of training.

In other words, the fact that you’re naturally skinny doesn’t necessarily mean that you’ll struggle to gain muscle when you start lifting weights.

Starting out with an ectomorph body type – tall and skinny – doesn’t mean that you have less potential for growth than someone who was already muscular before they started training.

Some people build muscle very quickly when they start lifting weights, and see impressive results after only a few months. Others tend to progress a lot more slowly.

RELATED: How Long Does It Take to Build Muscle?

However, there’s no evidence to show that knowing your somatotype has any value when it comes to predicting who will be the fast and slow responders.

Some people like to point out that body types are mentioned in numerous studies, which automatically means that somatotyping has been validated by science, and is therefore completely reliable.

The subject of somatotyping does show up in the scientific literature.

However, most of the research looks at how body type varies across different sports, and between elite and non-elite athletes, as well as exploring the link between somatotype and athletic performance.

To repeat, describing someone’s body type is very different to prescribing a diet and training program based on that body type.

Somatotypes and Training

Chances are you’ve come across some sort of “train right for your body type” article, which explains how the three different somatotypes should train.

For example, this article advises that endomorphs should do more than 15 repetitions, and take only 30-45 seconds of rest between sets.

Mesomorphs, on the other hand, should do 8-12 repetitions, and rest for 30-60 seconds between sets. Ectomorphs should train with lower reps (5-10) and heavier weights, and take longer between sets.

But what evidence are these recommendations based on?

Where is the research to show that mesomorphs benefit to a greater extent than endomorphs by doing 12 reps per set, rather than 15 or 5? Or that ectomorphs benefit to a greater extent than mesomorphs by resting for longer between sets?

There’s a reason nobody cites any studies or evidence to support these recommendations.

And that reason is very simple:

There isn’t any.

It’s all based on tradition, opinion or guesswork.

Recommendations that ectomorphs should limit themselves “to three workouts a week,” that mesomorphs “respond well to low reps and power moves,” or that endomorphs should “train with intensity” aren’t just useless.

They’re actually worse than useless, because they distract you from the things that really matter and mislead people into thinking they’ve discovered something important.

Body Type Eating

Some say that body type eating can provide information about how you respond to certain foods, and can be used to determine what your diet should look like.

One article, for example, advises that mesomorphs “typically do best on a mixed diet, consisting of balanced carbohydrates, proteins, and fats. A macronutrient split of 40% carbohydrate, 30% protein, and 30% fat can work well.”

Endomorphs, we’re told, “typically do best on a higher fat and protein intake with carbohydrate intake being controlled and properly timed (e.g., after exercise). A nutrient distribution for this body type might be around 25% carbs, 35% protein, and 40% fat.”

Ectomorphs, on the other hand, are supposedly “better off with more carbohydrate and less fat intake. A nutrient distribution for this body type might be around 55% carbs, 25% protein, and 20% fat.”

Once again, no evidence is provided to support any these recommendations, because there isn’t any.

None of this means that a diet shouldn’t be tailored to the needs of the individual. However, this tailoring should be based on your goals, lifestyle, activity levels, food preferences and so on.

Somatotype doesn’t come into the equation any more than the color of your eyes, whether you’re left or right handed, or what time you got out of bed this morning.

I’ve heard it said that these numbers are “just a guide” and that you “shouldn’t get too hung up on the numbers.”

If you shouldn’t get too hung up on the numbers, why put them out there in the first place? And they’re not much use as a guide if they’re completely interchangeable.

That is, you can replace the advice given to the ectomorph with the advice given to the mesomorph, and it won’t make a blind bit of difference.

Take an ectomorph, give him a mixed diet comprising 40% carbohydrate, 30% protein and 30% fat, which is supposedly “ideal” for a mesomorph, and he’ll do just fine.

On the flip side, put a mesomorph on a higher carb diet that’s supposed to be “optimal” for the ectomorph, and he’s going to do just fine as well.

In short, there’s no evidence to support the idea that having one body type means that you’re better off following a specific type of diet or training program.

Recommendations that a mesomorph should do this or an ectomorph should do that are perfect examples of Barnum statements: the advice is so vague and general that it could apply to anyone.

Why Thin People Can Still Be Fat

Just because two people have a similar body shape doesn’t mean they’re both going to respond in an identical way to the same diet.

Appearances can be deceptive. You can’t always tell just by looking at someone what’s going on internally, and your external appearance doesn’t always indicate your internal state of health.

For example, researchers have identified people with a normal weight based on traditional criteria, but their blood sugar and insulin levels are far higher than would be expected based on their weight alone.

Put differently, they’re thin on the outside but fat on the inside.

In one study, researchers at the University of Vermont found signs of metabolic obesity in almost 2 out of 10 women, despite the fact they had a normal body weight.

In fact, there was very little difference between the women in terms of weight and body fat. The metabolically obese women weighed slightly more (132 pounds) than the normal women (129 pounds). Their body fat percentage was also slightly higher (32% vs. 27%).

Despite a normal body weight, these young, apparently healthy women displayed a cluster of characteristics that, if left untreated, may eventually predispose them to type II diabetes and heart disease.

On the flip side, some people can be obese, but metabolically healthy.

Despite having large amounts of body fat, these individuals demonstrate remarkably normal to high levels of insulin sensitivity and a favorable cardiovascular risk profile.

According to some estimates, metabolically healthy but obese individuals could account for as much as 2 out of 10 of the obese population.

What does all of this mean for body type eating?

Someone who looks like an ectomroph (tall and thin), for example, doesn’t automatically have a “higher tolerance for carbs,” as some body type eaters would have you believe.

In fact, they may well be better off going in the opposite direction and eating fewer carbs. It all depends on what’s going on internally.

The Copy and Paste Brigade

A lot of the “body type” advice out there comes from people who are simply copying each other. That’s why so much of it sounds the same, which often creates the false impression that it’s valid.

If everyone is saying the same thing, there must be something to it, right?

In truth, the “copy and paste” brigade are just parroting something they’ve heard elsewhere. It reminds me of the infamous Yale University goal-setting study, which used to pop up whenever someone talked about the importance of writing down your goals.

The story goes something like this:

In 1953, a team of researchers interviewed Yale’s graduating seniors, asking them whether they had written down the specific goals they wanted to achieve in life.

Twenty years later, the researchers tracked down the same people and found that the 3% who had specific goals had accumulated more personal wealth than the other 97% of their classmates combined.

However, when a journalist set out to track down the source of the study, he came up empty handed.

So, he asked the motivational gurus who like to tell the story where it came from.

Here’s what happened next:

“Disconcertingly, when asked for their sources, they pointed at each other. Tony Robbins suggested asking Brian Tracy, who in turn suggested Zig Ziglar, a veteran of the motivational-speaker circuit, and a regular fixture at Get Motivated! seminars. Completing the circle, Zig Ziglar recommended asking Tony Robbins.”

In other words, everyone had been copying each other.

After an exhaustive search of the Yale archives, nobody could find any evidence that such a study had ever been done. The whole thing appears to have been made up.

Final Thoughts

None of this means that individual differences don’t exist, that everyone will see results at the same speed, or that training shouldn’t be tailored to the needs of the individual.

They do, they don’t and it does.

However, knowing your somatotype tells you very little about what your diet and training program should look like.

Somatotypes can’t predict how you should train and eat any more than astrology can predict your future, and it’s a subject you can happily file away in the “I don’t need to know anything about this” drawer.