Betty is really prone to weight gain, esp' since shes been spayed
I found just cutting down the food amounts didnt help, as she would then start to try and nick food, raid bins etc.
So her weight is now maintained with JWB Senior/ Light and Nature Diet Lite
She gets about 100g of JWB for brekki, and for tea, half a tray of Nature Diet Lite, with about 30g of JWB, for a bit of crunch.
I did weigh it out at first, bit now just figure it out in smalll handfuls.
It costs me £10 for a tray of Nature Diet, and £5 for a bag of JWB, both of which last just over a month, so not expensive at all
As for treats, I will some times use her JWB for if we're just out on a walk, but for training, I need something tastier, so to make up for it I just cut her tea down a little.
Oh and loads of ball throwing and swimming helps