How to Help Your Dog or Cat Lose Weight Safely

Overview

What you need

• Kitchen scale

  Cups and scoops can be off by 20% or more; weigh food in grams.

• A weight-loss diet, if recommended

  These are higher in protein and fibre and lower in calories, so pets feel fuller.

• Puzzle feeders

  Slow eating and add activity.

• A shared log

  So everyone in the household knows what has been fed.

Step by step

1. 1

   Score your pet's body condition

   Use the WSAVA body condition score charts. A score of 6 or 7 out of 9 is overweight; 8 or 9 is obese. Our pet BMI tool walks you through it.

2. 2

   See your vet

   Your vet can confirm the target weight and check for medical causes, such as an underactive thyroid in dogs, as well as arthritis that might limit exercise.

3. 3

   Work out how much to feed

   Calories are usually based on the target weight, not the current one. Our weight loss calculator gives a starting point; your vet may adjust it. Cornell Feline Health Center describes a cat losing weight safely on about 70% of its maintenance calories.

4. 4

   Weigh every meal

   Divide the daily amount into meals and weigh it. Count every food your pet gets, including chews, table scraps and food used for medication.

5. 5

   Cut and swap treats

   Keep treats under 10% of daily calories. Use pieces of the daily kibble, green beans or carrot for dogs, or a few kibbles in a puzzle ball for cats.

   Careful: Never use grapes, raisins, onion, garlic or anything with xylitol as treats.

6. 6

   Add activity gradually

   For dogs, extend walks slowly and add sniffing games and swimming if suitable. For cats, schedule short play sessions with wand toys two or three times a day, and put food in places they have to climb or walk to.

7. 7

   Weigh and adjust

   Weigh your pet every 2 to 4 weeks. Aim for about 1–2% of body weight a week for dogs and 0.5–1% for cats. If weight loss stalls for a month, reduce food by about 5–10% with your vet's guidance.

8. 8

   Maintain the new weight

   Once your pet reaches its target, increase food slightly to stop further loss, and keep weighing monthly. Many pets regain weight if old habits return.

Common mistakes

• Feeding by scoop or by eye

  Why it backfires: Small errors add up to a lot of extra calories each week.

  Do this instead: Use a kitchen scale for every meal.

• Forgetting extra food

  Why it backfires: Treats, chews and family members' scraps often add up to more than the meals.

  Do this instead: Keep a shared log and agree one treat allowance for the whole household.

• Cutting a cat's food drastically

  Why it backfires: Rapid weight loss can trigger fatty liver disease.

  Do this instead: Lose weight slowly under your vet's supervision.

• Relying on exercise alone

  Why it backfires: It's hard to burn off overfeeding with exercise.

  Do this instead: Combine measured food with more activity.

Sources

1. Penn Today: Dogs fed a reduced-calorie diet lived nearly two years longer
2. WSAVA body condition score charts
3. AAHA: 2021 Nutrition and Weight Management Guidelines
4. Cornell Feline Health Center: Care of obese cats

We check guides against veterinary sources and update them when guidance changes. How we write and review.