My dog is overweight: a safe, gradual feeding plan

Written by Josh · Founder of petportioncalc.com · About the author

By Josh · Reviewed and updated: 2026-09-17

Dog weight loss comes down to two habits: measure every meal and weigh your dog every two weeks. The six-step plan below covers the calorie target, the transition, and how long each stage should take.

Weight loss in dogs is not complicated, but it is slow, and almost all of it comes down to measuring what you feed and checking the result every couple of weeks. This page takes you through it in six steps, and tells you how long each stage should take so you can tell the difference between a plan that is working and one that has stalled.

How long will it take?

Pet type

Dog Cat

Current weight

lb kg

Target weight Use your veterinarian's ideal weight if you have one. Otherwise estimate it from the body condition score — see step 2 below. Enter the same unit you used above.

Work out the timeline Reset

Step 1 — Confirm it is actually overweight

Start with your hands, not the scale. Run them along the ribs behind the front legs, look at the waist from above, and look at the tuck from the side. If the ribs are hard to feel under a layer of fat and the waist has disappeared, the dog is carrying too much. The body condition score page walks through all three checks in a minute.

Do this before anything else, because the most common mistake in this whole process is deciding a dog is overweight when it is not, and then putting it on a diet it does not need.

Step 2 — Get a target weight

Your vet can give you a number in a few seconds, and that is always the best option, particularly if the pet is more than a little overweight. If you are working it out yourself, the body condition score converts to a percentage in fixed steps rather than a range: each point above ideal is equivalent to 10% overweight — BCS 6 is 10% over, 7 is 20%, 8 is 30% and 9 is 40% (AAHA nutrition and weight management guidelines).

Then estimate the target the way the guidelines do, by subtracting that percentage from the current weight rather than dividing by it. Their own worked example is a 45 kg Labrador at BCS 8 out of 9: 30% overweight, so the ideal weight is about 45 × 0.7 = 32 kg. Apply the same arithmetic to your own pet and you have a target to feed against.

Write the target down. A target you have not written down drifts, and so does the plan.

Step 3 — Work out the daily amount for the target, not the current weight

This is the step people get wrong. A dog on a diet should be fed for the weight it is aiming at, not the weight it is now — feed it the amount that maintains its current weight and it will maintain its current weight indefinitely. Put the target weight into the calculator and use the figure it gives you.

The multiplier applied here is 1.0 against the target weight's resting energy requirement — deliberately below every maintenance row, and it overrides the senior and activity rows rather than stacking with them. The arithmetic is published in the open reference dataset (CC BY 4.0), so the figure this page quotes can be re-computed independently.

The calculator also produces a treat allowance for that target weight, which is where most diets quietly fail. Treats, table scraps, dental chews and the food used to hide a pill are all calories, and they are the ones nobody writes down.

The formula behind that amount: RER = 70 × (ideal weight in kg)^0.75, and the daily target is that figure × 1.0 — the full resting energy requirement of the ideal weight. The table above gives it for four common weights.

Step 4 — Know what a safe rate looks like

Dogs can safely lose 1 to 2% of body weight per week. Faster than that and you risk muscle loss rather than fat loss, which is the opposite of the goal. The calculator above uses 1% by default — the slow end of that band — and shows you the full range in weeks so you know what "on schedule" looks like.

Cats are different, and this part is not optional. Veterinary guidelines put the safe feline rate at 0.5 to 2% of body weight per week — AAHA gives 1–2% as the ceiling and APOP uses 0.5–2% — and many clinicians start a cat near the lower end of that band rather than the middle. Two rules override everything else. A cat that refuses a reduced ration must not be starved into compliance: significant caloric restriction lasting 48–72 hours can cause hepatic lipidosis, which is frequently fatal, and overweight cats are at the highest risk. And if your cat is more than 20% above its target weight, that is a veterinary plan rather than a home one.

Step 5 — Measure, do not estimate

A diet that works on paper can fail in the bowl. If your measuring drifts by 10% — which is what a levelled cup scooped by feel typically does — a 187 g portion becomes 206 g, and the plan is running 10% behind without anything looking different.

The measuring page covers five methods ranked by accuracy, including how to work out your daily grams using only a bathroom scale. Whichever you use, use the same one every day.

Step 6 — Weigh in every two weeks and adjust in small steps

Weigh your pet every two weeks — weigh yourself, then yourself holding the pet, and subtract — and check the body condition score again. Then do one of three things:

What usually derails a dog diet

• Treats. The single biggest cause. Count them, cap them, or swap to something small — the treat page does the arithmetic.
• Other people in the house. A diet only works if everyone is feeding the same number. If two people feed the dog, write the daily amount on the food bin.
• Dog food that is not the dog's. In a household with more than one pet, the overweight dog is often finishing somebody else's bowl.
• The cat's food. Cat food is more calorie-dense than dog food and it is rarely measured.
• Starting too hard. A steep cut produces a hungry, miserable dog and an owner who gives up in week two. The safe range is deliberate: it is slow because slow is what lasts.

When to involve your vet rather than do it yourself

The honest expectation

A 5 kg loss on a 30 kg dog takes eight to seventeen weeks on a safe rate, and the first two are the hardest because the dog notices the change before the owner sees any result. That gap is where most diets fail. It is worth knowing at the start, so that week three feels like being on schedule rather than being stuck.

Once the target is reached, the work is not over: the calorie figure changes to a maintenance amount for the new weight, and weighing every two to four weeks during the maintenance phase is the standard recommendation. A growing number of veterinary teams also score body condition at those check-ins, because a stable weight can hide a shift from muscle to fat. Dogs that regain the weight they lost almost always do so because the plan stopped when the target was reached rather than because it failed.

The daily calorie target, by ideal weight

Here is the number the rest of this page assumes. A dog on a weight-loss plan is fed for its ideal weight, not its current weight — that is what creates the deficit. The target is the resting energy requirement of that ideal weight:

Grams are calculated on a dry food of 350 kcal per cup at 110 g per cup — the same basis as the feeding chart on our feeding chart by weight page. Your food will differ; use the kcal on your own bag. For a full set of weights, including cats, use the calculator.

Some clinical guidance starts a canine weight-loss plan at 80% of the resting energy requirement for the ideal weight. We use the full RER of the ideal weight as the default — it matches the calculator above, and your veterinarian may set a different target. Whichever figure you and your vet settle on, the plan does not change: feed that amount, weigh the food, and adjust on the two-week check in Step 5.

Frequently asked questions

Calculate the daily amount for the target weight →
Check the body condition score →
Work out the treat allowance →
Recently neutered? The amount has to change →
Free feeding is what usually causes the drift →

If you are feeding for an ideal weight rather than the current one, the breed calculator prefills a starting weight from the breed standard and lets you correct it. · calorie calculator by breed · cat weight-loss plan · neutering and weight · senior nutrition

If the dog is older as well as overweight, the senior dog calorie calculator gives the two senior tiers before you set a target.

Why a weight-loss plan is a rate, not a number

The target weight is the easy part; the rate is what makes a plan safe. Losing weight too quickly costs lean mass along with fat, and in dogs that lean-mass loss is hard to recover. The commonly used guardrail is roughly 1–2% of body weight per week — faster than that is a reason to slow down, not to congratulate yourself.

There is also a floor: a diet must not drop below the resting energy requirement, because below that the body starts breaking down its own tissue to cover the deficit. This page calculates a mild deficit from the target weight and states the current maintenance figure alongside it, so you can see the gap you are actually running — and see when the deficit has become too large.

What this cannot do: it cannot distinguish fat loss from muscle loss. That needs a body condition score and, ideally, a muscle condition score at the vet — the scale alone will not show it.

How this page was checked: Numbers traced to NRC (2006), WSAVA and AAHA guidance; units re-derived independently; safety statements limited to the species they were established for. Our review method

Sources

• National Research Council — Nutrient Requirements of Dogs and Cats (2006). Resting energy requirement — the floor a weight-loss diet must not go below. nationalacademies.org/publications/10668
• MSD Veterinary Manual — Nutrition, Small Animals. Obesity, energy restriction and the risks of losing weight too quickly. msdvetmanual.com
• AAHA — nutritional assessment guidelines for dogs and cats. Body condition and muscle condition scoring to track what is being lost. aaha.org
• Tufts University, Cummings School of Veterinary Medicine — Petfoodology. Why the rate of loss matters as much as the direction. sites.tufts.edu/petfoodology