Does doing sit ups help shed weight?

I am a medium height young woman,5'6 that is,I weigh 53 kgs and i want to shed 8 lbs of weight.I do 30 minutes of yoga twice a day,cycle 4 kilometres (moderate intensity) and do about 60 sit ups everyday.I have recently begun this routine.How long would it take to shed these 9-8 lbs?(Ignoring the metabolism that is)