I have a dog that is fairly overweight - I have cut down her food intake but now she is scavenging everything she can get hold of when we are on walks etc - Is their anything I can bulk up her food with that won't cause her to put on weight but that fills her up? She is fed raw.

I would fill her up by adding veg ti her meal.The easiest way is to puree it or put it in a food processor(I use a juicer) and mix it with her meat.
Archer

I agree with Archer. When I had a real gannet of a Labrador I used to bulk her food out with cabbage. She was happy and her weight went down. The side effect of the weight coming down is that the dog gets more active which then means that she then uses up more energy which brings her weight down even faster!

Best wishes, John