Don't feed "free choice" -- which means there is food available all the time and your pet eats whenever it wants. Instead, take the amount of food your doctor recommends and divide it up into two or three meals.
Limit snacks and access to other food -- just like in a human diet.
Start a walking program. If your overweight pet is really out of shape, don't push it too hard. Start with one block (300 yards) per 10 pounds of body weight, twice a day. Early morning or evening walks are best -- avoid scorching sidewalks, high heat and humidity.
A good leash for fat pets is a Gentle Leader Easy Walk Harness because it discourages dogs from pulling on the leash while walking by redirecting pressure across the chest and shoulder blades, instead of the tracheal area. Unlike traditional leashes, the harness reduces coughing, gagging and choking when your dog attempts to pull forward.