How Much to Feed an Overweight Cat to Lose Weight

Feed an overweight cat about 80% of the calories she'd need at her ideal weight, split across two or three small meals a day, and expect the whole loss to take six to twelve months. Rushing it can trigger hepatic lipidosis, a fatal liver condition that shows up when a cat drops weight too fast or stops eating for even a few days.

Set the target weight first

You can't dose calories without a goal number. Ask your vet for an ideal weight based on body condition score (BCS), or estimate at home using the standard 9-point scale. Most cats score 5/9 at ideal. Each score above 5 represents roughly 10% over ideal weight.

Quick example. A 15-pound cat with a BCS of 8/9 is about 30% over ideal, so target weight sits near 11.5 pounds. A 12-pound cat at BCS 7/9 is about 20% over, targeting roughly 10 pounds.

Don't guess by breed. A large-frame Maine Coon at 15 pounds may be lean. A small domestic shorthair at 15 pounds is obese. BCS beats the number on the scale.

The calorie math

Two numbers matter: resting energy requirement (RER) and daily energy for weight loss.

RER at ideal weight = 70 × (ideal weight in kg)^0.75

For a fast approximation: RER ≈ 30 × (ideal kg) + 70

For weight loss, feed 80% of RER at ideal weight. Some vets go to 70% for stubborn cases, but going lower without supervision raises the lipidosis risk.

Worked example, 11.5 lb target (5.2 kg):

• RER ≈ 30 × 5.2 + 70 = 226 kcal/day
• Weight-loss feeding: 0.8 × 226 ≈ 180 kcal/day

Now check the bag. A typical dry weight-loss food runs 300 to 380 kcal per cup. At 180 kcal/day, that's roughly half a cup of dry food, total. Most owners overfeed by two to three times this amount without realizing it.

Wet food math is easier per can. A 5.5-oz can of pate-style food is usually 150 to 200 kcal. One can plus a small kibble topper often lands right at target.

Wet food helps, but ratios matter

Higher moisture and higher protein help cats hold muscle while shedding fat. A reasonable split for weight loss:

• 60 to 80% of daily calories from canned or fresh food
• 20 to 40% from measured dry (for dental abrasion and grazing)

Look for at least 40% protein on a dry-matter basis and under 15% carbohydrate. Prescription weight-loss diets (Hill's Metabolic, Royal Canin Satiety, Purina OM) are formulated to keep cats fuller on fewer calories. If you're feeding an over-the-counter food, expect more begging.

Split meals, kill free-feeding

A bowl left down all day is the single biggest cause of cat obesity. Two meals a day is the floor. Three or four small meals is better. Automatic timed feeders help if you work long days.

Weigh food on a kitchen scale (grams, not cups). A "cup" scoop varies by 20 to 40% depending on how you shake it. That's the difference between losing weight and staying stuck.

The hepatic lipidosis warning

This is the reason you can't just cut food in half. When an overweight cat stops eating or eats far too little, her body mobilizes fat into the liver faster than the liver can process it. The liver fills with fat, function crashes, and she stops eating entirely. Emergency treatment involves feeding tubes and hospitalization that can run $2,000 to $5,000, with survival around 60 to 80% when caught early.

Safe rate of loss: 0.5 to 2% of body weight per week. For a 15-pound cat, that's about 1.2 to 4.8 ounces per week. Weigh weekly on a baby scale. If she loses more than 2% in a week, feed a little more. If she refuses food for more than 24 hours, call your vet the same day. Cats aren't dogs. They can't skip meals.

Realistic timeline

Going from 15 pounds to 11.5 pounds at a safe 1% weekly loss takes about six months. Many cats stall for a few weeks, then start losing again. That's normal. Adjust calories down by 10% only if she's been stalled for four consecutive weeks and body condition hasn't improved.

Movement helps too. Two five-minute wand-toy sessions a day burn maybe 20 kcal, but they also cut the boredom eating that wrecks progress.

When to loop in your vet

Book a weigh-in and bloodwork before starting if your cat is:

• Over 20% above ideal weight
• Older than 10
• Diabetic, hyperthyroid, or on any long-term medication
• Refusing to eat measured portions

Untreated diabetes and hyperthyroidism both mess with weight and appetite. You want those ruled out or managed first.

Run your cat's numbers through the PawMath food portion calculator to get a starting daily kcal target dialed to her target weight.

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