<s>[INST] hi im having a diet that i eat once every 1-2 days and only a little , i used to weigh like 240 lbs now im around 180 lbs and 7.2ft tall , my skin near my left knee is turning black , my mom s skin is turning black too but under her left eye... whats the reason ? and thanks if you answer me ... i really need to know what caused this [/INST] Thanks for the query posted .  I would be pleased to answer your question. Your condition and your mothers condition of skin darkening are totally different. Your condition on the knee can be due to friction or hormonal changes or vitamin B 12 deficiencies. You should get Chemical Glycol peels done for the knee to lighten it or even have multivitamin supplements. Avoid friction on the area.  For your mothers condition : She should apply over the counter vitamin C serum on the area twice a day daily Thanks and take care </s>