If you’ve been around the (gym) block, chances are you’ve heard the terms ‘somatotypes’ or ‘body types’ being bandied about. The theory categorises people according to their natural build: ectomorphs (leaner), mesomorphs (more muscular) and endomorphs (broader, typically with more body fat).

Fans of this concept say our natural build can tell us something about our likelihood to gain muscle, lose fat and respond to training. However, in recent years, the idea that we can all be neatly divided into one of three body types has increasingly fallen out of favour.

Now, a new study, which has been published as a preprint in SportRxiv, has debunked the idea that your body type has any bearing on the gains you make in the gym.

Researchers wanted to find out whether your natural body type, or ‘somatotype’, can predict how well you respond to resistance training. In particular, they investigated whether people who started out with more typically ‘mesomorphic’ characteristics (aka, a naturally more muscular build) experienced greater increases in muscle size and physical performance after training.

Of course, it’s important to note that the research is currently a preprint and has not yet been peer reviewed.

The researchers:

• Recruited 40 untrained young men
• Asked them to complete 9 weeks of full-body resistance training: 2 sessions per week
• Gave them a programme including the leg press, leg extension, lat pulldown, Smith machine bench press, biceps curls and triceps extensions, generally using sets of 8-12 reps

Before training, the researchers assessed each participant’s somatotype, including how strongly they had mesomorphic characteristics. They then measured changes in muscle size using several methods. They also tested maximal strength, muscular endurance, lower body power and knee extension strength.

At first glance, being more mesomorphic appeared to be associated with slightly greater improvements in muscle growth and performance. However, the effects were small and largely considered too small to be practically meaningful.

Once the researchers accounted for the other components of participants’ body types, there was little evidence that being more mesomorphic independently predicted how well someone responded to resistance training.

There was one interesting exception: that greater mesomorphy was associated with somewhat larger improvements in bench press one-rep max. However, this was an exploratory finding, and the researchers caution that it needs to be replicated before drawing firm conclusions.

The researchers concluded that somatotypes appear to have limited value for predicting how much muscle or overall performance someone will gain from resistance training. In other words, having a naturally muscular-looking physique doesn’t necessarily mean you’ll respond exceptionally well to lifting, and starting with a naturally slimmer or less muscular build doesn’t mean you have poor muscle-building potential.

The findings challenge the long-standing idea that your natural ‘body type’ decides your potential in the gym. Someone who doesn’t look naturally muscular shouldn’t assume they’re destined to be a ‘hard gainer’, just as someone with a naturally muscular build shouldn’t assume they’ll make faster gains.

Rather than tailoring your expectations around whether you think you’re naturally ‘built’ for muscle, the study suggests there’s little reason not to focus on consistent resistance training and assessing how you actually respond over time.

It’s important to note that this was a small study of 40 untrained young men over just nine weeks, so we can’t assume the same findings apply to experienced lifters or other populations. And this isn’t to say that genetics don’t influence how we respond to training. Rather, these findings suggest that simply categorising someone by their body type may tell us little about their muscle-building potential.

Overall, it’s an encouraging reminder not to let a perceived ‘body type’ put a ceiling on your training goals. Stay consistent, track your progress and let your own response to training determine what you’re capable of.

If there’s one thing Kori Sampson knows, it’s how to optimise your body composition for performance. To tap into his knowledge as an elite athlete and coach, we asked him to create a 4-week plan to help you move faster, recover quicker and keep pushing when the fatigue sets in – all while improving your muscle-to-fat ratio.

Ready to build muscle, burn fat and come out the other side looking, feeling and performing better? Click here to get 14 days of free access to the plan via the Men’s Health app.