Low Body Fat: When body fat reduces, especially in the limbs or torso, the layer of fat that usually hides veins becomes thinner, making them more visible.

Exercise and Weight Lifting: Increased blood flow during exercise can make veins to swell and become more noticeable. Over time, with regular training, muscles grow and push the veins closer to the surface.

Hot Weather: Warm temperatures cause veins to dilate (widen) as the body tries to cool itself. This temporary change can make them more visible, especially in the arms and legs.

Aging: As we age, our skin removes elasticity and becomes thinner. This allows underlying structures like veins to show through more easily.