Ectomorph: Naturally thin with narrow frames, long limbs and fast metabolisms. They struggle to gain weight or muscle easily. Think lean and wiry.
Mesomorph: Naturally athletic and muscular. Broad shoulders, narrow waists, and respond quickly to training. They build muscle and shed fat with minimal effort.
Endomorph: Stockier build with a higher tendency to store fat. Wider hips, shorter limbs, and a slower metabolism. Gains weight easily—muscle and fat alike.