Body weight and nutritional status of the mother does impact fertility more often when weight is low and food intake (low vitamin and mineral content) is poor. You most likely can lose the 20 to 25 extra pounds without negatively impacting your ability to conceive as long as you lose it slowly (1 to 2 pounds per week) and exercise (30 minutes 3 to 5 times per week). A severe weight loss program (losing too much weight too quickly) could upset your ovulation cycle. Why don’t you ask your doctor to see a Registered Dietitian who can plan an individual, balanced nutritious weight loss diet? There are some good suggestions in the Overweight Topic.
There is no magic fertility food.