We’ve all heard (or said) it before: ‘I’m big-boned,’ or, ‘No matter what I eat my weight stays the same.’ Thanks to genetics, every single body really is different. Whether we devote time every day to cardio, avoid any food that comes out of a wrapper, or lift weights until our muscles give out, some aspects of our physique are predetermined.
But we’re not talking about being ‘pear’ or ‘apple’ shaped here—we’re not fruit. Scientists use the following three categories to identify body types (not shapes): ectomorph, mesomorph, and endomorph.
Most people display some mix of all three body types, with one type being more dominant, explains Lindsay Carter, Ph.D., Professor Emeritus, San Diego State University School of Exercise and Nutritional Science. So while one of these categories might seem the most spot-on, keep in mind that it’s not necessarily your end-all-be-all.
We all know someone who can live off of microwave mac and cheese and soda without gaining a pound (the injustice!). These naturally thin people—sometimes called ‘hard gainers’ in the fitness world—are classic ectomorphs.
“Ectomorphs tend to be thinner and leaner, with a smaller bone structure,” explains Ryan Andrews, M.A., M.S., coach at Precision Nutrition. Picture a marathoner or endurance athlete with little body fat and a slim build. Look out for thin limbs, in particular.
They may also be a little more high-energy—always moving—thanks to a high metabolism, Andrews adds.
Related: 5 Myths About Your Metabolism—Busted
People with a naturally athletic build and balanced proportions fall into the second category: mesomorphs.
“They’re not overly thin or stocky, but have a good amount of muscle mass,” says Andrews. Think bodybuilders and athletes whose bodies have a more built, strong appearance.
Mesomorphs stay pretty lean, but may put on muscle more easily than others when exercising or strength-training.
Those who carry a little extra weight or describe themselves as ‘big-boned’ fall into this third category.
“Classic endomorphs have a stockier build with a bigger and heftier base and bone structure,” says Andrews. They typically carry their weight pretty evenly throughout their body. Football linemen, powerlifters, and women who identify as curvy often have these characteristics.
Endomorphs may find that their diet impacts their body more easily, and have the tendency to store fat instead of burning food off as fuel.
Is Your Body Type Your Destiny, Though?
So maybe you identify most with the ectomorph body type. Does that mean you’ll never have the strong, curvy legs you’re after? Or maybe you’re an endomorph. Is dropping a few pounds or racing a triathlon out of the question? Absolutely not.
“Genetics are definitely a factor, but your environmental patterns and behaviors are also important,” says Andrews. If you focus your training and nutrition on the goals you want to achieve, you can change your body to a degree, he says. So don’t abandon that strength-training routine or your dream of running a marathon. If you feel like your efforts are stalling, working with a nutritionist and coach or trainer may help push you closer to those goals.
And the environmental factor? It can affect any body type. “Someone may be born naturally leaner and skinnier, but if they have an unhealthy lifestyle and a poor diet, they may end up looking more like an endomorph,” says Andrews. The best way to avoid this? “Living a healthy lifestyle with plenty of physical activity, balanced nutrition, and ample sleep is key,” he adds. This goes for everyone. You’re not stuck!