Maya, the Australian shepherd mix that we recently adopted, has gained 4 lbs. in the two weeks we've had her. She was slightly emaciated when we got her - the vet said about a 3 on a scale of 1-10. We'll level her out at about 50 lbs. and monitor from there.
Belle, our golden retriever, had gotten to 99 lbs. before we reeled her in. She's down to 73 lbs. now and that's an ideal weight for her as she's a BIG female. She gets 2 cups of a low-fat food per day, plus all the veggies she can eat, so that works nicely for her.
All 3 dogs get a daily walk of usually 1.6 miles (1 mile on the treadmill when the weather's bad) and they play pretty hard in the snow, so they're burning off some of that energy too.