These body type classifications have their roots in discredited pseudoscience—but they're still common shorthand at the gym.

Medically reviewed by Mallory Christopherson DC, FMT, CSCS If you are an ectomorph, you may struggle to gain weight due to ...

Medically reviewed by Mallory Christopherson DC, FMT, CSCS Body types are categorized as ectomorph, mesomorph, or endomorph.You may have a high metabolism and need more protein if you are a mesomorph.