Can i lose Belly fat doing lots of crunches ?

You can't really target body fat, its just you have to burn more calories than you consume daily to remove excess body fat. And its best to lose weight slowly so that your skin doesn't remain stretched and loose where your fat deposit were situated. I suggest a shift in diet, an increase in water intake, and a combination of aerobic exercise like walking at least 20 minutes every other day, and the days you don't walk you do 20 minutes of exercising with weights. Taking a day off after every 3 days of consecutive walking/weight usage: Walk-Weights-Walk-Rest-Weights-Walk-Weights-Rest etc. The walking gives your body a chance to rest from the weight exercises, while the water intake will allow your body to heal and flush out broken down fat from your body. Hope that helps.