First off, choosing the right low-fat spread will cut down the saturated fat in your cake significantly, and skimmed milk or low fat yogurt can often be used to replace whole milk or single cream. Another handy swap is to use fat-free ricotta cheese with a little sweetener to replace thick creams in recipes.
To sweeten your cakes, it’s a good idea to use lower amounts of anything containing sugar. Try adding half or three-quarter quantities of the cane sugar that you usually would and your favourite recipes really will still taste delicious. You could also replace this lower quantity with alternatives like dates, ripe bananas or fresh fruit. These make delicious, moist cakes, but do still count towards your daily allowance of sugar, so be sure to keep an eye on how much you add to your baking.