Both of our dogs needed to lose some weight. Dad gives them too many treats! What has worked well for me is to cut down on their kibble and add peas and carrots to their food. I buy the frozen pea and carrot mix, microwave enough for two or three days and add that to their food. It fills them up and cuts out the extra calories. I've tried to retrain Dad...but you know how that goes.
As far as training treats go...I like the Authority brand Liver Treats available at Petsmart. Our dogs love them even if they already ate. One thing I really like about them is they are a soft treat and you can pinch off whatever size you want. My dogs will do anything for even a little crumb of these.