Obesity in dogs rarely develops overnight. It happens little by little, often without the owner noticing, precisely because you see the dog every day. Obesity is not about appearance, but about what the body can tolerate: joints, breathing, heat regulation and the risk of anesthesia are all affected. Here we explain how to assess your dog's body condition, why dogs put on weight, and how weight loss can be carried out safely.
Is my dog overweight?
Weight alone rarely gives the answer. Two dogs of the same breed and weight can have completely different body compositions. The best assessment is to combine weight with a systematic assessment of body condition – and it is done with your hands, not your eyes.
Body Condition Score – BCS
Body Condition Score is a standardized scale used in veterinary practices worldwide. The most common version goes from 1 to 9, with 4–5 out of 9 being considered ideal condition for a dog. The assessment is based on three simple tests you can do at home:
- The ribs. Run your flat hand along the ribcage. You should be able to feel the ribs through a thin layer of fat without having to press, and without them protruding visibly.
- The waist from above. Sit over the dog and look down. Behind the rib cage, the body should taper, giving the dog an hourglass shape.
- The abdominal line from the side. From the rib cage and back, the belly should pull upwards. A belly line that goes straight back or hangs down indicates overweight.
In long-haired breeds, the fur hides a lot. In this case, the hands are absolutely crucial – a dog can look well-proportioned and still have a clear layer of fat under the fur.
Muscles are assessed separately
Body condition and muscle mass are two different things, and they are assessed separately. A dog can be overweight and at the same time have lost muscle – this is not uncommon in older dogs. Feel the spine, shoulder blades and pelvis: there should be a covering of muscle there, not just skin over bones. Because fat can accumulate at the same time as muscle mass decreases, the weight on the bathroom scale can remain the same even though the body has changed significantly. This is one of the reasons why we assess weight, body condition and muscle together during health checks.
How much should the dog weigh?
There is no definitive answer for each breed. The weight stated in a breed standard is a description of the breed, not an ideal weight for the individual dog. Body build, gender, muscle mass and whether the dog is neutered all play a role.
A useful starting point is what your dog weighed when it was fully grown and in good shape. Otherwise, weigh your dog regularly and at the same weight so that the numbers are comparable. You are welcome to use our scale – it costs nothing, and it makes changes over time much easier to detect.
How common is obesity in dogs?
The figures vary, and they depend heavily on who assesses the dogs. In American studies where veterinary personnel have themselves assessed the body condition, the proportion of overweight dogs has been around 60 percent in recent years. Settlements based on diagnoses registered in medical records land at closer to a third, simply because obesity is often not recorded as a diagnosis. Norwegian operators state everything from "up to a third" to "about half".
There are no good Norwegian figures, and the exact percentage is honestly not the important thing. The point is that obesity in dogs is common enough that it is worth checking your own dog – and that it is easy to get used to what it looks like.
Why is obesity a health problem?
Adipose tissue is not just stored energy. It is active tissue that secretes signaling substances and contributes to a persistent, low-grade inflammatory state in the body. This is part of the explanation why obesity affects several organ systems simultaneously, and not just puts mechanical stress on the skeleton.
Obesity in dogs is associated with an increased risk of, among other things:
- Osteoarthritis, joint pain and increased strain on joints that are already damaged
- Reduced exercise tolerance and heavier breathing
- Poorer heat regulation and increased vulnerability in hot weather
- insulin resistance
- Dermatitis in skin folds, which becomes deeper when the dog lays down
- Increased risk during anesthesia and surgery
- Reduced mobility, activity level and quality of life
In addition, being overweight has been identified as one of several risk factors for acute pancreatitis in dogs. This connection is less well-established than the points above, but it is worth knowing about – not least because it points directly to leftovers from dinner.
Obesity and longevity
Two studies are worth knowing about, and both must be read with reservations.
In a review of more than 50,000 middle-aged, neutered family dogs at about 900 clinics in North America, researchers compared normal-weight dogs with overweight dogs across 12 breeds. Across all 12 breeds, the median lifespan was shorter in the obese dogs. The difference was greatest in Yorkshire terriers—13,7 years versus 16,2 years—and least in German shepherds, at 12,1 years versus 12,5 years.
The second study followed 48 Labradors in pairs from eight weeks of age until death. One of each pair was fed 25 percent less food than its partner throughout its life. The food-restricted dogs lived longer, and signs of chronic disease appeared later, on average.
The caveats are important. The first study is retrospective and shows a correlation, not that weight loss in itself gives more years of life – and it only included neutered dogs. The second involved lifelong, moderate food restriction from puppyhood, in a single breed, and was funded by a food manufacturer. That is quite different from slimming down an adult, overweight dog. The numbers should therefore not be read as a promise to your dog. But they point in the same direction, and that is the direction we are headed.
Obesity and breathing
Being overweight can increase the work of breathing and provide less reserve to draw on when the dog exerts himself. In short-nosed breeds, this comes on top of an already narrow airway. A study of pugs published in 2026 found that fat is also deposited inside the airway itself – on the tongue and around the larynx – and that dogs with severe BOAS had more fat around the larynx than dogs with moderate degrees. The study is small, included only one breed, and it did not examine the effect of weight loss. It therefore points to a possible mechanism for how obesity can worsen airway obstruction – not to how much breathing improves by slimming the dog. The advice on weight loss in BOAS still stands, and is also given by the specialist community in Cambridge who developed the grading method.
If you have a short-nosed dog, you can read more about assessment and grading on our page about BOAS grading.
Obesity and diabetes – dogs and cats are not the same
It is worth being precise here, because the two species are often referred to together. Obesity causes insulin resistance in both dogs and cats. In cats, obesity is a well-established risk factor for developing diabetes. In dogs, the disease mechanism is different: diabetes is caused by the loss of beta cells in the pancreas and thus permanent insulin deficiency, and obesity has not been established as the cause.
That doesn't mean that weight is irrelevant. Insulin resistance makes it harder to control a dog that already has diabetes. You can read more in our article about diabetes in dogs.
Why does the dog become overweight?
The basic mechanism is always the same: over time, the dog takes in more energy than it uses. But how easily this happens varies greatly from dog to dog.
Energy intake is greater than consumption
What is added to the daily ration is often what makes the difference: treats, chew bones, leftovers, cheese in medicine and rewards in training. In small dogs, this quickly becomes a lot. A five-kilogram dog has a small daily requirement, and a single treat can make up a significant portion of it.
If there are more than one person in the household, it is also easy for the dog to be fed multiple times without anyone having full control. One person responsible for the daily ration solves more problems than you might think.
Castration changes energy needs
The energy requirement decreases after castration, while the appetite of some dogs increases. Without adjusting the amount of food, the dog will gain weight. This is predictable, and therefore also possible to prevent. We will go into more detail on the page about dog castration.
Race and heritage
Obesity occurs in all breeds, and a dog of a breed not mentioned here can still gain weight. At the same time, heredity plays a real role. In Labrador retrievers and flat-coated retrievers, a variant in the gene POMC has been found to be associated with higher body weight, more body fat and a stronger motivation to eat. The variant was more common among Labradors selected as service dogs than among family dogs.
The point is not that weight is beyond the owner's control. The point is that differences in appetite between dogs are real and measurable. A dog that always seems hungry is not necessarily underfed.
Age, pain and reduced activity
Activity levels usually decline with age. Osteoarthritis and other joint problems result in less movement, which results in more weight, which places more strain on the same joints. Lameness is not always obvious – some dogs just become slower, take shorter walks or hesitate on stairs. Read more about what could be behind it in our article about dog that limps.
Disease and medicines
Disease is a rarer cause of obesity than an imbalance between intake and consumption, but it does exist, and some images are worth recognizing.
Low metabolism (hypothyroidism) typically results in weight gain without the dog eating more, along with lethargy, mental sluggishness, reduced exercise tolerance, the dog seeking warmth, and changes in fur and skin. The picture varies greatly from dog to dog, and the absence of a single sign does not rule out anything. At the same time, hypothyroidism is among the most overdiagnosed conditions in dogs. The diagnosis is made on blood tests together with the clinical picture – never on weight alone.
Too much cortisol, either from the body itself (Cushing's syndrome) or from treatment with cortisone preparations, often causes a distended abdomen that can look like overweight. It is due to the redistribution of fat and a weakened abdominal wall, and is often accompanied by increased thirst and urination, thin skin and hair loss. The dog is not necessarily heavier - it is just shaped differently.
Contact us if your dog is gaining weight without changing its diet, or if the weight gain is accompanied by lethargy, coat changes, or increased thirst.
When a big belly isn't fat
A belly that grows gradually over weeks and months may be caused by something other than fat: fluid in the abdominal cavity, enlarged organs, pregnancy or uterine inflammation. If the belly feels tense, or changes shape more quickly than the weight would indicate, the dog should be examined rather than put on a diet.
A belly that gets big within hours is not overweight. Contact your veterinarian immediately if your dog:
- gets a visibly bloated or tense belly within a short time
- repeatedly vomits without anything coming up
- is restless, drools a lot and doesn't want to go to bed
This could be a stomach twister. The condition is life-threatening and cannot wait until the next day. We describe the signs in more detail in the article about dog vomiting.
How to safely help your dog lose weight?
The formula is familiar to most people: less energy in, more activity out. What determines whether it actually succeeds is whether the plan is concrete enough to be implemented in a busy everyday life – and whether someone follows up on it along the way.
Set a target weight and calculate your daily ration
Start by recording your dog's weight and body condition, and set a realistic target weight with your veterinarian or animal caretaker. Then calculate how much energy your dog should have per day.
The feeding recommendation on the package is only a starting point. It is designed to cover an average maintenance requirement, and is often too high for the individual dog. In the event of weight loss, the daily ration should therefore be calculated based on the dog's target weight and energy needs, and then adjusted according to how the weight actually develops in the first few weeks.
Measure the feed
A kitchen scale provides far more precise portioning than measuring cups or eye measurements, especially with dry food, where a few extra grams per meal add up over weeks. A practical tip is to measure out the entire daily ration in the morning and leave it ready – then treats are also taken from the same amount, and you can immediately see what is left.
Weight reduction feed if needed
In cases of significant weight loss, it is rarely enough to give less of the usual food. If you reduce the amount enough to have an effect, you also reduce protein, vitamins and minerals, and risk the dog getting too little of the nutrients it still needs.
A complete food intended for weight loss is formulated for precisely this purpose: to provide sufficient protein, vitamins and minerals at a lower energy intake. Many such foods are also designed to help promote satiety and preserve muscle mass during weight loss, but the composition varies between manufacturers. The choice of food should therefore be adapted to the individual dog, and we are happy to help with that assessment.
Treats are included in the daily ration
Treats should make up a small portion of your dog's daily intake - a general guideline is about ten percent of their daily energy intake. The rest should come from a complete food to ensure a balanced diet. Feel free to use bits of their daily ration as rewards in training.
Leftovers from dinner are worth cutting out completely. Beyond the calories, several common human foods are directly dangerous for dogs.
Increase activity gradually
Activity contributes to both energy expenditure and quality of life, but a dog that has been out of shape will not tolerate a sudden increase. Increase the length of the walks before increasing the pace, and see how the dog is the next day. Several short walks are often better than one long one.
Be extra careful if your dog is stiff, lame, elderly or has a short snout. Overweight dogs also have a hard time with heat, so limit your activity to the cooler part of the day in the summer and read about heatstroke in dogsSwimming can be a good option for dogs with joint pain, provided the dog is comfortable in water.
Weigh the dog along the way
Weigh your dog regularly and at the same weight, preferably every two weeks. A safe rate for a dog is about one to two percent of its body weight per week. For a 30-kilogram dog, this corresponds to around 300 to 600 grams.
If it goes faster than this over time, or the dog does not lose weight at all even though the plan is followed, the plan should be adjusted by a veterinarian – do not tighten it further on your own. Lack of weight loss can also be a signal that something else is going on. Contact us if your dog stops eating, becomes lethargic or has diarrhea along the way.
How to maintain the weight afterwards?
Once the target weight is reached, the amount of food must be adjusted up again slightly to stabilize the weight – otherwise the dog will continue to lose weight. Continue with measured portions, regular routines and the same control over the treats as during the actual weight loss.
Weight and body condition are assessed during routine health checks, and any new weight gain is caught while it is still small. For older dogs, this is included in the senior check.
When should you contact a veterinarian?
Contact us if:
- the dog is gaining weight without any change in feeding or activity
- the weight gain is accompanied by lethargy, changes in the coat, increased thirst or the dog seeking warmth
- the abdomen appears distended or grows faster than the rest of the dog
- the dog is breathing heavily, has less energy or stops during walks
- the dog is stiff, limps or hesitates on stairs
- weight not coming off even though the plan is followed
- you are unsure whether the dog is in the right condition
A weight assessment takes just a few minutes, and the earlier it is done, the easier it is to deal with. If you also have a cat, many of the same principles apply – but with some important differences, which we will go over in the article about obesity in cats.
