The first time I made this cake I found it a little dry and sweet, so I made the following adjustments, which resulted in a deliciously moist and full flavour cake which is still low in calories. I estimate 130 calories per slice, allowing 12 slices.
I used three quarters of a cup of plain flour instead of wholewheat and I replaced the extra 2 tablespoons of flour with cornflour. I used 3 tablespoons of sunflower oil (i.e. an extra spoon).
I reduced each sugar by half (i.e a quarter cup of each) and increased the cocoa to a half cup. I folded in 100g of fresh raspberries just before I put in in the oven. I cooked it at 160C in a fan oven for 30 minutes.