An overweight dog should eat enough calories to match the resting energy requirement (RER) for its ideal body weight, with no additional multiplier. That means feeding roughly 30% to 40% fewer calories than what a typical adult dog eats at maintenance. The exact amount depends on your dog’s target weight, but the formula is straightforward once you know that number.
Figure Out Your Dog’s Ideal Weight First
Before you can calculate how much to feed, you need a target weight. Your vet can help pin this down, but you can get a rough idea at home using a body condition score (BCS) on a 9-point scale. A score of 4 or 5 is ideal. Dogs scoring 6 or 7 are overweight, and 8 or 9 are obese. The physical signs are consistent: ribs covered by a thick layer of fat that makes them hard to feel, no visible waist when viewed from above, and little to no tuck where the belly meets the hind legs. Dogs at a 7 or 8 often have an almost flat torso from the side.
If your dog is moderately overweight (BCS 6 or 7), the ideal weight is typically 10% to 20% below current weight. For an obese dog (BCS 8 or 9), it could be 25% to 35% less. A 70-pound dog with a BCS of 7, for example, might have an ideal weight around 58 to 60 pounds. Starting with a reasonable estimate matters because the calorie calculation builds directly on it.
How to Calculate Daily Calories
The standard formula veterinarians use starts with resting energy requirement: RER = 70 × (ideal body weight in kg)0.75. For weight loss, you multiply that RER by a factor of 1.0, meaning you feed only the resting energy requirement for the target weight. A normal neutered pet eating at maintenance would use a multiplier of 1.6, so feeding at 1.0 is a significant calorie cut.
Here’s what that looks like in practice for a few common target weights:
- 10 kg (22 lb) ideal weight: 70 × 100.75 = about 394 calories per day
- 20 kg (44 lb) ideal weight: 70 × 200.75 = about 662 calories per day
- 30 kg (66 lb) ideal weight: 70 × 300.75 = about 897 calories per day
- 40 kg (88 lb) ideal weight: 70 × 400.75 = about 1,113 calories per day
To use this formula yourself, convert your dog’s ideal weight to kilograms (divide pounds by 2.2), raise that number to the 0.75 power (most phone calculators have this function), and multiply by 70. That’s your daily calorie budget.
Weigh the Food, Don’t Scoop It
Once you know the calorie target, check the calorie density on your dog food’s packaging (listed as kcal per cup or per kilogram) and measure accordingly. But here’s the part most people get wrong: using a measuring cup is surprisingly inaccurate. A study that tested dog owners measuring kibble with standard scoops found individual accuracy ranged from nearly 48% under to over 152% above the correct amount. Smaller portions, which are exactly what overweight dogs need, were measured least accurately.
A kitchen scale that reads in grams eliminates this problem entirely. Weighing food is considered the gold standard for portion accuracy. If your food lists 350 kcal per cup and you need 662 calories a day, that’s roughly 1.9 cups, but the gram weight on the bag will tell you precisely how many grams that equals. Weigh it every time. When you’re restricting calories by 30% to 40%, a sloppy scoop can erase the entire deficit.
Choose Food That Keeps Your Dog Full
Cutting calories works, but your dog will tell you about it. Begging, counter-surfing, and stealing food all increase when a dog feels hungry. The type of food you feed can make a real difference here. Research comparing different diet compositions found that a combination of high protein (about 103 grams per 1,000 calories) and high fiber (about 60 grams per 1,000 calories) reduced voluntary food intake by roughly 50% compared to diets that were high in only one of those nutrients. In plain terms, dogs fed the high-protein, high-fiber diet were significantly less interested in eating more food after a restricted meal.
Weight management dog foods are formulated along these lines. They pack more protein and fiber into fewer calories, so your dog gets a physically larger portion that’s more satisfying. If you’re using a regular adult food, you’re simply feeding a smaller amount of calorie-dense kibble, which leaves the bowl looking empty and your dog looking at you. Switching to a weight management formula, or at least one with higher fiber and protein content, makes the whole process easier to sustain.
Low-Calorie Treats That Won’t Wreck Progress
Treats are the hidden budget-breaker in most dog weight loss plans. A single large biscuit can contain 100 calories or more, which is a significant chunk of a daily budget that might only be 500 to 700 calories total. Swap commercial treats for vegetables. Green beans are a veterinarian favorite for weight loss because they’re filling and very low in calories. Cucumbers are another excellent option with minimal caloric impact. Baby carrots work too, though they’re slightly higher in natural sugar.
Whatever treats you give, count them in the daily calorie total. A good rule is to keep treats under 10% of daily calories. For a dog on a 600-calorie plan, that’s 60 calories or less from treats, with the remaining 540 coming from meals.
How Fast Your Dog Should Lose Weight
A safe rate of weight loss for dogs is 1% to 2% of total body weight per week. For a 70-pound dog, that’s about 0.7 to 1.4 pounds weekly. This pace sounds slow, but it protects muscle mass and avoids metabolic stress. At this rate, a dog that needs to lose 10 pounds will take roughly 7 to 14 weeks to reach its goal.
Weigh your dog every one to two weeks, ideally at the same time of day. Most vet clinics have walk-on scales you can use for free. If you’re not seeing any change after two to three weeks, reduce the daily portion by about 10% and reassess. Plateaus are normal and don’t mean the plan has failed. They mean the plan needs a small adjustment. As your dog loses weight, its calorie needs actually decrease slightly, so periodic recalculation keeps things on track.
Add Exercise Gradually
Diet does most of the heavy lifting in canine weight loss, but exercise matters. A large survey of UK dog owners found that dogs exercised fewer than three times per week were over 60% more likely to be overweight than dogs exercised daily. Dogs walked for only 10 minutes or less had more than double the odds of being overweight compared to dogs exercised for over an hour.
For an overweight dog, especially one that hasn’t been active, start with short daily walks of 15 to 20 minutes on flat ground and build from there. Swimming is excellent if your dog tolerates water, since it’s easy on joints that are already bearing too much load. The key is daily consistency rather than occasional long outings. Exercising once a day was just as protective against weight gain as exercising multiple times a day, so a single steady walk each day is a perfectly good target.
When Weight Gain Has a Medical Cause
Some dogs gain weight even on reasonable portions because of an underlying condition. Hypothyroidism is the most common medical cause of unexplained weight gain in dogs. The telltale signs go beyond the scale: lethargy and decreased interest in activity, cold intolerance, hair loss along the trunk or tail base that isn’t related to itching, a dull or brittle coat, darkened skin, and recurring skin or ear infections. If your dog shows several of these signs alongside weight gain, a simple blood test can confirm or rule out a thyroid problem. Treating the underlying condition makes weight loss through diet dramatically more effective.
Cushing’s disease and certain medications (particularly steroids) can also drive weight gain that won’t respond to calorie restriction alone. If you’ve been feeding a calorie-controlled diet for four to six weeks with no measurable change, a medical workup is a reasonable next step.