There are many causes of varicose veins, but they are one more side effect of obesity.

Veins are vessels that carry blood to the heart. The returning blood has to travel against gravity in the veins; this is done through muscle contractions and a system of valves that allow blood to travel in only one direction, meaning they allow blood through, but not back. Sometimes, however, these valves become weakened and do not close completely. This then allows some blood to flow backward where it can end up collecting.  

Chronic venous insufficiency occurs when veins in the legs cannot pump enough blood back to the heart. The blood pools, legs may feel heavy and painful and the ankles may swell. The condition often leads to the occurrence of varicose veins — enlarged, swollen, and tortuous (twisting) veins, generally blue or dark purple.

lim person, bulging veins are usually visible on the skin of the calf.  However, swollen veins in the obese are not visible on the skin surface due to excess fat.  Basically, they're hiding under layers of fat. What this means is that the discomfort and heaviness of the legs, symptoms of leaking veins, are almost always initially attributed to the obese person's weight problem itself rather than the possibility of a varicose vein.  Over time, the pressure in the leaking veins cause leg ulcerations and only then do many patients go and see a specialist for the first time.  So, basically, a slim person with varicose veins will know about that condition early on.  An obese person's varicose veins won't present themselves until much later when the problem is much worse.

As for dealing with the problem, well . . . it makes sense that the depth of varicose veins in the obese leg makes it more difficult for the surgeon to treat. Minimally invasive laser treatment is much more challenging and uncomfortable if the patient chooses the local anesthetic option. On the other hand, giving overweight patients a general anesthetic carries a much greater risk.

The first step in avoiding varicose veins is prevention: Managing your weight and blood pressure is crucial.