The short answer

A weight-loss calorie target isn't just "less than they're eating now." It starts from your pet's target weight, not their current weight, and is typically set around their Resting Energy Requirement (RER) at that target, adjusted for activity level. Feeding based on current weight just maintains the weight that's already the problem.

Before you cut anything, have your vet confirm the target weight and rule out medical causes of weight gain. From there, a starting point generally works out to feeding roughly 80% of what a pet at a healthy weight and the same activity level would eat, then adjusting based on how the weight trend actually looks after 2 to 4 weeks.

Why "just feed less" usually stalls out

Cutting a portion by a rough guess, a bit less kibble, skip a treat, rarely produces a predictable result, because it isn't anchored to a number. Two dogs at the same current weight can have very different target weights and very different activity levels, and both of those change how many calories actually produce loss instead of just slower gain.

Doing the math once, from an actual target weight, turns a vague "cut back" into a specific number of calories per day, and from there, a specific number of cups or grams of your pet's actual food.

Body condition score comes first

Before setting a calorie target, you need an honest read on where your pet actually is: whether they're a body condition score of 6, 7, 8, or 9 out of 9 changes both the target weight and the urgency. If you haven't assessed body condition yet, that's the first step, not the calorie math.

How fast should the weight actually come off

Slow and steady is not just a platitude here, it's a medical necessity. For dogs, a conservative pace is typically around 1 to 2% of body weight per week. For cats, it needs to be slower and more carefully managed: cats that lose weight too quickly are at real risk of a serious liver condition (hepatic lipidosis), so rapid loss is a warning sign, not a win.

That pace also means reassessment matters more than the initial number. A calorie target set once and never revisited either stalls (as your pet's metabolism adjusts to a lower weight) or, less commonly, overshoots. Weigh-ins every 2 to 4 weeks, with a portion adjustment if the trend is off pace, is what actually gets a pet to target weight instead of just started in that direction.

Activity is a real lever for dogs, less so for cats. An extra walk or two genuinely moves the needle for a dog's energy balance. For cats, movement matters, but the food side of the equation carries more of the weight-loss work. Don't rely on activity alone to close a large calorie gap in either species.

Turning the number into an actual portion

Once you have a daily calorie target, you still need to convert it into a real-world portion of your pet's specific food, since foods vary widely in calorie density (a 300 kcal/cup food and a 450 kcal/cup food need very different portions to hit the same target). The bag's feeding guide won't reflect a weight-loss target since it's calibrated for maintenance at current weight, not loss toward a target weight.

KibbleLab's weight loss tracker does this calculation directly from published veterinary guidelines: enter your pet's current weight, target weight, and activity level, and it returns a daily calorie target and the actual portion size for whatever food they're eating, then walks the pace and reassessment schedule with you. Dog- and cat-specific versions account for the pace differences above.

Key Takeaway

A weight-loss calorie target is calculated from target weight, not current weight, roughly 80% of maintenance calories at that target as a starting point. Dogs can typically lose about 1 to 2% of body weight per week; cats need a slower, more carefully managed pace to avoid a serious liver condition. Reassess every 2 to 4 weeks and adjust the portion, since a target set once and never revisited tends to stall.

Sources & Further Reading

  • AAHA Nutritional Assessment Guidelines for Dogs and Cats, 2021 update.
  • WSAVA Global Nutrition Committee. "Nutritional Assessment Guidelines." 2011.
  • National Research Council. "Nutrient Requirements of Dogs and Cats." 2006.
  • NAVC Pet Nutrition Coach Certification Coursework. "Weight Management." 2023.

Content based on NAVC Pet Nutrition Coach Certification coursework and AAHA Nutritional Assessment Guidelines.

KibbleLab Explains articles are educational, and are not veterinary advice. Before starting an elimination diet, a weight plan, or any major diet change, talk to your veterinarian.

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