Serena, exercise does make us hungry, especially when we just start a new program because of a thing called homeostasis.
Basically, our bodies don't mind putting on weight but they don't like losing weight and to this end want to maintain the status quo.
This status quo is homeostasis and when we exercise and burn more energy than usual, our bodies want us to replace that energy by eating more food so we at least maintain our current weight.
The "trick" then when we're exercising is to slip some nutrient rich and low calorie snacks into our diet so that we are eating more than usual but there is a net deficit of energy. If we can replace any of the high calorie foods that we normally eat with lower calorie options, all the better.
After a little while, our bodies get used to the exercise and its new lower weight and the homeostasis "bar" is set lower.
Because we no longer need as much energy to maintain our new weight our hunger pains are less severe.
The bottom line of all this is we need to be careful in the first few days, weeks and months of our new exercise program not to give in freely to these hunger pains and avoid the mistake of rewarding our exercise effort with nutrient poor, high calorie foods (like pizza, potato chips, chocolates, biscuits and the like).
The great news is that if we can do this, it eventually gets easier and easier.
Keep up the great work and please keep us posted about your progress towards your goal weight.