Is my dog overweight? How to tell, and what to do
Your dog's weight matters more than you might think. Not in a guilt-inducing way: most overweight dogs got there through small, well-meaning habits that gradually added up. But carrying extra weight puts real strain on a dog's joints, heart, and lifespan. The good news is that with a few simple changes, most dogs can get back to a healthy weight and stay there.
Here's how to check where your dog stands, and what to do if they need to lose a few kilos.
How to tell if your dog is overweight
The number on the scale only tells part of the story. A healthy weight for a Labrador looks very different from a healthy weight for a Whippet. A much better tool is the body condition score (BCS): a system used by vets worldwide to assess body fat independently of breed size.
The BCS runs from 1 to 9. A score of 4 or 5 is ideal. Dogs scoring 6 or 7 are overweight; 8 or 9 is obese.
You can check your dog's BCS at home with two simple tests:
The rib test: Run your hands along your dog's ribcage with light pressure, like pressing on the back of your hand. You should be able to feel each rib individually without pressing hard. If you have to press firmly to find them, or can't feel them at all, there's likely a layer of fat in the way.
The waist check: Stand above your dog and look down. You should see a visible waist: a narrowing behind the ribs. From the side, the belly should tuck upward slightly toward the hind legs. If your dog's sides look straight or rounded and there's no visible waist, that's a sign they're carrying too much weight.
If you're unsure, your vet can give your dog an official BCS score at their next check-up.
Why it matters
Extra weight isn't just about appearance. Research consistently shows that overweight dogs have shorter lifespans and spend more of their later years in discomfort. Studies tracking dogs over their lifetimes have found that lean dogs live significantly longer than their heavier counterparts: and with better mobility and quality of life in their senior years.
The health consequences of excess weight in dogs include:
Joint disease and arthritis: extra weight puts more pressure on cartilage, speeding up wear. This is particularly serious in breeds already prone to hip and elbow problems.
Diabetes: excess body fat interferes with insulin sensitivity, and overweight dogs have a significantly higher risk of developing diabetes mellitus.
Breathing difficulties: fat deposits around the chest restrict lung expansion; this is especially problematic in flat-faced breeds like French Bulldogs and Pugs.
High blood pressure and heart disease: both are more common in overweight dogs.
Reduced stamina and heat tolerance: overweight dogs tire more easily and are at greater risk of heatstroke.
Surgical and anaesthetic risk: any procedure becomes more complex and higher-risk when a dog is overweight.
Put simply: every extra kilo your dog carries costs them something.
Which dogs are most at risk
Any dog can become overweight with the right combination of extra food and too little exercise. But some breeds are genuinely predisposed to gaining weight more easily.
Labradors carry a specific mutation in a gene called POMC that affects how they process satiety signals: they simply feel hungrier than other dogs. Studies have found this mutation in over 20% of Labradors. If you have a Lab, a measured feeding routine isn't optional; it's essential.
Other breeds with a higher tendency to gain weight include Cocker Spaniels, Dachshunds, Beagles, Basset Hounds, Cairn Terriers, and Cavalier King Charles Spaniels. Neutered dogs also tend to have lower energy requirements than intact dogs, and older dogs need fewer calories as their metabolism slows.
What causes weight gain in dogs
The underlying cause is almost always a calorie surplus: more energy coming in than going out. But several specific habits contribute:
Overfeeding: Most dogs are fed more than the guidelines on their food packaging recommend, and those guidelines are already generous.
Too many treats: Treats can easily account for 20-30% of a dog's daily calorie intake without owners realising it. A few biscuits here, a piece of cheese there: it adds up fast.
Human food: Table scraps and leftovers are calorie-dense. A small cube of cheddar contains roughly the same calories as a full dog biscuit.
Not adjusting for age: Puppies need more calories; adult and senior dogs need fewer. Many owners don't adjust portion sizes as their dog gets older.
Low exercise levels: Dogs who don't get enough movement each day will gain weight even on normal portions.
How to help your dog lose weight safely
Weight loss in dogs should be gradual: around 1-2% of body weight per week is a realistic and healthy target. Crash dieting or dramatic calorie cuts can be harmful.
Start by measuring. Most owners are surprised when they actually weigh out their dog's food. Use kitchen scales rather than the scoop that came with the bag. A standard "cup" can vary wildly depending on kibble size and density.
Reduce calories by around 20%. If your dog is mildly overweight, cutting their current daily intake by 20% and maintaining their exercise routine is usually enough to start shifting weight. Your vet can calculate a precise target based on your dog's ideal body weight.
Swap treats for low-calorie options. Carrot sticks, cucumber, and small pieces of apple are all dog-safe and very low in calories. If you use treats for training, try using a portion of your dog's daily kibble allowance instead.
Keep track of everything. Write down what your dog eats each day: main meals and treats. It's surprisingly easy to underestimate intake. The Lassie app lets you log treats and rewards alongside your dog's health record, which can help you spot patterns.
Increase exercise gradually. If your dog isn't used to long walks, build up slowly. Swimming is particularly good for overweight dogs as it's low-impact on joints.
Choose a weight-management food. Many vets recommend a specific weight-loss diet rather than simply reducing portions of a regular food. These are formulated to keep dogs feeling full while delivering fewer calories.
When to see a vet
Your dog scores 7 or above on the body condition score
You've tried reducing food for 4-6 weeks with no change in weight
Your dog is struggling to exercise, breathes heavily at rest, or seems uncomfortable
Your dog has gained weight rapidly without an obvious cause: this can sometimes signal a thyroid or hormonal issue
You want a personalised weight loss plan with regular monitoring
Your vet can calculate your dog's ideal target weight, recommend the right food, and track progress at regular weigh-ins. For dogs who are significantly overweight, this kind of structured support makes a real difference.
Frequently asked questions
How do I know if my dog is a healthy weight?
Use the body condition score: run your hands along your dog's ribs: you should feel them easily without pressing hard. Looking from above, there should be a visible waist behind the ribs. A score of 4 or 5 out of 9 is ideal. If you're unsure, your vet can assess at the next check-up.
How much should I reduce my dog's food to help them lose weight?
A reduction of around 20% from their current daily portion is a good starting point for mildly overweight dogs. Weigh the food using kitchen scales rather than a scoop for accuracy. Your vet can calculate a precise target based on your dog's ideal weight.
Can my dog lose weight just by cutting treats?
For mildly overweight dogs, yes: treats can account for a significant percentage of daily calories without owners realising. Swapping to low-calorie treats like carrot or cucumber and accounting for treat calories within the daily allowance can make a measurable difference.
The truth is that most overweight dogs got there because their owners love them. Treats are how we show affection; an empty bowl feels unkind. But the most loving thing you can do for your dog is help them stay at a weight where they can run, play, and move comfortably for as long as possible. That's worth a smaller portion.
If you're concerned about your dog's weight, a conversation with your vet is always the best first step.
