Swimming in the morning on an empty stomach seems not so bad.
When you keep your hart frequentie in the relaxed zone (60-70%) you will be more efficient in burning fat then on another moment of the day. 45% fatburning is no exeption. Keep drinking water, even in the pool, to keep you body hydrated. And when you stop swimming do not go for the sugar candy, but take a nutricious healthy breakfast.
This way of training gives your metabolism a boost that works all day and you will burn fat more efficient when your metabolism works better.
And what if your hunger seems to give you the feeling that you don't have enough energy to do the workout? You can take a smell bite. Take half a banana or half a energy bar and save the other half for after your workout. You feeling of a lack of energy is your bloodsugar that drops. Just a little bite will start your fatburing machine and because your body is low on carps it will go for the fat reserves much quicker then when you exercise after a larger meal.
Remember that your lever needs a lot of water to maintain it's work of fat oxidation. If you don't drink it will not do what you want it to do.