I need help getting my body a specific way i want it and i wanna know if anyone can help me?

ok so like i have an amazing backside. everyone tells me that and im really proud of it : ). but... my stomach is getting out of order. i don't have a muffin top or anything i just want to stop the weight gain b4 it gets to that point without losing any weight in spot where the sun don't shine. is there an excersie where i can lose weight in one are but no where else??????