For Students
Do body types actually determine your macros?
"Ectomorph," "mesomorph," and "endomorph" get treated as science-backed categories for setting macros. The original research behind them was never about diet at all.
Where the idea actually came from
The somatotype system was developed in the 1940s by psychologist William Sheldon, who used it to try to correlate body shape with personality and temperament — a theory that has since been discredited as pseudoscience. It was never a validated framework for nutrition or exercise prescription; fitness culture adopted the three body-type labels decades later and retrofitted diet advice onto them.
What actually should set your macros
Your protein, fat, and carb targets should come from your actual body weight, activity level, and goal — not a body-shape label. Someone who identifies as an "ectomorph" and someone who identifies as an "endomorph" at the same weight, activity level, and goal need essentially the same macro targets; individual differences in metabolism and training response are real, but they're not reliably predicted by a 1940s personality typology.[1]