Safe weight-loss calories for your dog

The formula

Target kcal/day = 0.8 × (70 × target_weight_kg0.75)

That's the RER (Resting Energy Requirement) for the goal weight, multiplied by 0.8 to build in a modest deficit. AAHA recommends this conservative approach over aggressive 0.6× restriction because it preserves lean muscle mass and avoids triggering metabolic adaptation.

Sources: AAHA Weight Management Guidelines for Dogs and Cats (2014, reaffirmed 2021). NRC, Nutrient Requirements of Dogs and Cats (2006). WSAVA Body Condition Score chart. AAHA / AAFP are US veterinary-association bodies; UK readers see equivalent BSAVA / RCVS guidance, Australian readers see AVA, Canadian readers see CVMA — same fundamental veterinary science.

Why 1–2% weekly is the safe ceiling

The AAHA Weight Management Guidelines draw the line at 1–2% of body weight per week for a reason. Above that pace, two things go wrong. First, the deficit becomes large enough that the dog burns lean muscle for energy alongside fat — sarcopenia accelerates and the dog comes out of the diet weaker, with a lower basal metabolism that makes rebound weight gain almost inevitable.

Second, in already-overweight dogs, aggressive calorie restriction risks ketosis and (in dogs with hepatic fat infiltration) liver dysfunction. The NRC baseline of 0.8 × RER-at-target-weight produces a deficit large enough to lose at the safe rate but small enough to preserve lean mass. Crash diets at 0.5 × RER routinely fail in the literature — fast weight loss followed by faster regain.

Why cats need a slower deficit

If you're adapting this approach to a cat, cut the pace in half: 0.5–1% per week, not 1–2%. Cats face a specific risk dogs don't — hepatic lipidosis (fatty liver syndrome), in which a cat in negative energy balance mobilizes fat to the liver faster than the liver can metabolize it. The liver becomes infiltrated, function deteriorates, and the cat stops eating, which deepens the deficit and the lipidosis. It's a leading cause of death in overweight cats put on aggressive diets without veterinary supervision.

The AAFP-AAHA Feline Life Stage Guidelines are explicit: cat weight loss should be slow, monitored, and never involve a complete fast (even 48 hours of zero intake can trigger lipidosis in an obese cat). Use a calorie deficit closer to 0.85–0.9 × target-weight RER, and re-weigh every 2 weeks rather than monthly.

When to add exercise vs cut food

For dogs, exercise is a supporting actor in weight loss, not the lead. A 25 kg dog walking briskly for 30 extra minutes burns ~80–100 kcal — the same as 1 cup less kibble. The food side scales faster and is more reliable, but exercise matters for lean-mass preservation, joint mobility, and behavior. The right combination depends on your dog's starting condition.

If your dog is mildly overweight (BCS 6/9) and otherwise healthy, lead with food restriction and add 15–20 minutes of additional daily walking. If your dog is obese (BCS 8–9/9), AAHA recommends a vet-supervised plan — joint stress and cardiopulmonary load mean ramping exercise too fast risks injury. Start with food restriction alone for 4–6 weeks, then add gentle leash walking as fitness allows. Swimming and underwater treadmill work are joint-friendly options for severely overweight dogs.