Information excerpted from an article by C.C. Holland
To start your dog back on the road to slimness, start by aiming for a 10 percent weight loss – or a rate of about 1 percent of his body weight per week. A slow approach is recommended both because it allows for a more gradual change in feeding, and because studies show that rapid weight loss can increase a loss of lean body mass, which in turn can contribute to weight regain. (Lean body mass, which includes organs, are the primary drivers of basal metabolism and burn energy at far higher levels than fat mass does. Reducing the amount of lean tissue can create diminished energy requirements, so a dog can regain weight even if he’s eating less.) In other words, forget the idea of crash diets for your dog; slow and steady wins this race.
The first step: weigh your dog. Next, calculate how much your dog actually eats. Begin by listing all the food your dog gets every day, including treats and table scraps, and add up the total calorie count. Some commercial foods carry calorie information on the label; for others, you may need to take the initiative and contact the manufacturer for more details.
Make sure you take portion size into account. If the recommended ration of your kibble is two standard cups a day, but if you’re using a 16-ounce Big Gulp container to measure out the food, you’re actually feeding your dog twice the allowance – and twice the calories.