Skinny, veiny arms can be attributed to poor diet, while the bulging veins themselves are a sign of the swelling and hardening of muscle that pushes the veins closer to the surface. Low-fat diets and low body weight cause these veins to be more noticeable, according to Softpedia. While in most cases the bulging veins are an aesthetic issue, they sometimes can indicate blood clots, infections or tumors.
Celebrities such as Angelina Jolie and Sarah Jessica Parker find their veiny arms under scrutiny in magazines such as E! Online and Daily Mail, but the phenomenon occurs in bodybuilders as well, and for similar reasons, states Pop Sugar. Extremely active lifestyles combined with low-sodium diets and low body fats cause the veins to become more prominent. Dietician Sharon Richter, quoted on Softpedia.com, states that these people's arms may be a symptom of dehydration as a side effect of the low sodium levels or participation in cleansing and fasting diets.
However, bulging veins also result from weak heart valves that allow blood to leak back into the veins and collect there, reports Better Medicine. Rarely, tumors and infections can exert localized pressure on veins, resulting in bulging and congestion. If the condition is painful or uncomfortable, the person should seek treatment from a local health practitioner in order to avoid complications.