skin became dark after weight loss

hey all......i have lost a considerable amount of weight in last one year....all i have done is reduced the amount of food i eat.....and now my skin has become dark.....i donno if its coz of weight loss or coz of less food i eat.....if someone can help me with this i will be glad.....i want my glow back on my face which is all gone with fats.....thanx