How to help your dog lose weight: a vet-approved guide to a happier, healthier dog
You love your dog. You feed them well. You give them treats because they deserve them. And somewhere along the way, they've put on a bit of extra weight. You're in very good company. Research from the PDSA suggests that a significant proportion of dogs in the UK are carrying more weight than they should.
Those extra pounds matter more than you might think. They affect how your dog feels, how they move, and how long they're likely to be around. A landmark study of over 50,000 dogs found that overweight dogs can live up to two and a half years less than dogs at a healthy weight. Two and a half years of walks, belly rubs, and time together.
The good news is that it's very fixable. With the right approach, most dogs can get back to a healthy weight steadily and safely. No crash diets. No misery. Just a sensible plan and a bit of patience.
Is my dog overweight? How to tell
Before changing anything, it helps to know where you're starting from. Your vet can do a proper body condition assessment, but there are three simple checks you can do at home right now. For a more detailed guide, take a look at our Is My Dog Overweight? blog post.
Run your hands along your dog's sides. You should be able to feel their ribs without pressing hard. If you're having to dig around for them, there's more padding there than there should be.
Look at your dog from above. There should be a visible waist behind the ribs, a gentle narrowing before the hips. If your dog's silhouette is more oval than hourglass, that's telling you something.
From the side, their belly should tuck up behind the ribcage, not sag down level with or below the chest. If the undercarriage is looking a bit low-slung, that's extra weight.
None of these checks are exact science, but together they give you a pretty reliable picture. If two or three of them suggest your dog is carrying extra weight, it's worth having a conversation with your vet.
Why carrying extra weight matters
It's easy to look at a chunky Labrador and think they just look well-loved. But carrying extra weight puts real strain on your dog's body in ways you might not see from the outside.
Joint problems are one of the most common consequences. Extra weight means extra pressure on hips, knees, and elbows with every step. Over time, this can accelerate wear on cartilage and may make conditions like arthritis worse. Dogs with joint problems move less, which can lead to more weight gain, which puts more pressure on joints. It's a tough cycle to break once it gets going.
Heart disease, diabetes, breathing difficulties, and increased risk of certain cancers have all been associated with excess weight in dogs. Overweight dogs are also more prone to heatstroke in warm weather and may struggle more under anaesthesia if they ever need surgery.
The lifespan research is hard to ignore. Overweight dogs may live up to two and a half years less than dogs at a healthy weight across 12 popular breeds. That's a big difference.
But every one of those risks starts to reduce as soon as the weight starts coming off. Even modest weight loss can make a real difference to how your dog feels and moves. It's one of those situations where doing something, even something small, genuinely helps.
What causes weight gain in dogs?
Most of the time, it comes down to calories in versus calories out. Too much food, not enough exercise, or both. Portions that are slightly too generous, treats that add up throughout the day, and a routine that's become a bit less active than it used to be.
But diet and exercise aren't always the whole picture. Neutering changes your dog's metabolism and appetite. Research suggests neutered dogs may need noticeably fewer calories to maintain a healthy weight, but most owners don't adjust portions after the operation. The risk of weight gain is thought to be highest in the first couple of years following surgery.
Certain breeds are more prone to gaining weight too. Labradors, Cocker Spaniels, Cavaliers, Golden Retrievers, Beagles, Pugs, and Dachshunds all tend to pile on weight more easily than others. In Labradors, there's actually a gene mutation that affects their sense of fullness, which is why yours acts like every meal is their first in weeks.
Age plays a role as well. Older dogs tend to have slower metabolisms and are typically less active, so they may need fewer calories even though their nutritional needs stay the same.
And sometimes there's a medical reason. Hypothyroidism, Cushing's disease, and certain medications like steroids can all cause weight gain that has nothing to do with how much your dog eats. If your dog is gaining weight without any obvious dietary explanation, a vet check should be your first step. Our guide on why your dog might be gaining weight covers all the common causes in detail.
How to help your dog lose weight: a step-by-step plan
Here's how to get your dog back to a healthy weight without making mealtimes miserable.
Start with your vet. Before you change anything, book a check-up. Your vet can confirm whether your dog is overweight, rule out medical causes, and help you set a realistic target weight. They'll also let you know if there are any health considerations to factor in, like joint problems that might limit exercise initially.
Work out their ideal weight. Your vet will help with this. Everything that follows, portions, calories, progress tracking, works from the target weight, not the current one. Feed for the dog you want, not the dog you have right now.
Switch to a lower-fat food. This is where the biggest difference happens. A weight management recipe is designed to reduce calories while keeping all the nutrition your dog needs. Fat Dog Slim was built for exactly this. It contains 50% chicken with just 9.5% crude fat, 30% less fat than our standard recipes. It includes L-carnitine, which may help support fat metabolism, slow-release carbs from oats to help your dog feel fuller between meals, and glucosamine and chondroitin, which may help support joints. Overweight dogs need their joints looked after while the weight comes off.
Get portions right. Weigh the food. Every time. Eyeballing portions is one of the biggest reasons dogs don't lose weight on a diet food. Use kitchen scales every time, as bulk density can differ from batch to batch, so a scoop that was right last week might not be right this week. Follow the feeding guide for your dog's target weight, and adjust based on how they respond over the first few weeks.
Sort out the treats. This is where the best intentions often come unstuck. It's worth keeping treats to a small proportion of your dog's daily intake, and your vet can advise on what that looks like for your individual dog. Swap biscuits and dental sticks for raw carrot batons, cucumber slices, or small pieces of apple. They're low in calories and most dogs love them. If you need training rewards, break them into tiny pieces or use a few bits of their daily kibble allowance.
Build exercise gradually. Diet is the biggest lever, but exercise makes a real difference too. If your dog has been less active, start gently. Short walks on flat ground, building up distance and pace week by week. Swimming is brilliant for overweight dogs because the water supports their joints while they get a proper workout. Even an extra ten minutes of walking a day adds up over time. The goal isn't marathon training. It's getting your dog moving more consistently.
And please, avoid crash diets. Cutting calories too drastically can actually cause your dog to lose muscle instead of fat, and it makes them miserable. Slow and steady is healthier, more sustainable, and much kinder.
Choosing the right food for weight loss
When you're looking for a weight management recipe, the key things are lower fat and calories while still providing enough protein to help support lean muscle. Slow-release carbohydrates like oats and rice can help your dog feel satisfied after eating rather than immediately campaigning for a second dinner. Ingredients like glucosamine and chondroitin may help support joints, which is a real bonus for heavier dogs. And the food should still taste good enough that your dog actually wants to eat it. The best diet plan in the world is useless if dinner gets ignored.
If you'd like to learn more about what to look for, our guide to choosing the best low-fat dog food covers it in detail.
Fat Dog Slim is available in both dry and wet recipes, so you can mix and match. The dry recipe has 50% chicken at 9.5% crude fat with added L-carnitine, which may help support fat metabolism. The wet version is made with 85% free-run chicken and has 25% less fat than our standard wet recipes. Mixing the two gives your dog variety at mealtimes and adds extra moisture to their diet.
How to transition your dog to a new food
Switching food too quickly almost always causes tummy trouble, which is the last thing you need when you're trying to help your dog feel better.
We always recommend switching over a two-week period, starting with around 10% new food and 90% current food, and gradually increasing the new food each day. This gives your dog's digestive system time to adjust without any fuss.
If your dog is a fussy eater, try warming the food slightly to release the aroma, or stir a little warm water through the dry kibble. Sometimes that's all it takes to get a hesitant dog interested.
Keep an eye on stools during the transition. A bit of softness in the first few days is normal. Anything more persistent, just slow the changeover down and give their tummy a bit longer to adjust.
Exercise tips for overweight dogs
Getting an overweight dog moving again takes a bit of thought, especially if they've been less active for a while or if they have joint issues.
Start on flat, even ground. Pavement or grass is ideal. Hills and uneven terrain put extra strain on joints that are already working harder than they should be. Short walks once or twice a day are a good starting point.
Build up gradually. Add a few minutes to each walk every week or so as your dog's fitness improves. You'll notice them moving more freely, breathing more easily, and actually wanting to go further. That's when you know it's working.
Swimming is one of the best exercises for overweight dogs. The water takes the weight off their joints while they get a proper workout. If there's a hydrotherapy centre near you, even better. Some dogs take to water naturally. Others need a bit of encouragement and a patient owner in wellies.
Keep it consistent. Several moderate walks a day will do more for your dog than one long weekend hike. Little and often beats occasional bursts every time.
And pay attention to the weather. Overweight dogs overheat more easily, so avoid vigorous exercise in warm weather. Early morning or evening walks are kinder on hot days.
How to track your dog's progress
Weighing your dog every couple of weeks gives you the clearest picture of how things are going. Many vet practices have walk-in scales and are happy for you to pop in without an appointment.
Healthy weight loss in dogs is gradual, and your vet can advise on a safe and realistic pace for your individual dog. What matters most is that the trend is moving in the right direction, steadily and consistently.
Body condition checks at home are just as useful as the scales. Run through the rib test, waist check, and tummy tuck every few weeks. You'll start to feel and see changes that the numbers alone don't capture. The first time you feel those ribs easily again is a genuinely brilliant moment.
If things aren't shifting after a month, go back to your vet. Sometimes portions need fine-tuning, sometimes the food needs changing, and occasionally there's a medical reason the weight is sticking. Don't give up. Just adjust.
When your dog reaches their target weight, that's not the finish line. It's the start of keeping them there. You may need to increase portions slightly or switch to a standard adult food depending on how active they are. Your vet can guide you on the right approach.
Because helping your dog lose weight isn't about putting them on a diet. It's about giving them back the energy to bound through the park, the comfort to lie down without aching joints, and the extra years to spend doing all the things you love together. That's what good food does. And that's what feeding them well is really about.
FAQs
How long does it take for a dog to lose weight?
It depends on how much weight needs to come off and your individual dog. Your vet can advise on a safe and realistic pace. A dog that needs to lose a couple of kilos might reach their target in two to three months. A dog with more to lose could take six months or longer. Patience matters here. Steady, consistent progress will always beat a crash diet.
How much should I feed my overweight dog?
Feed for your dog's target weight, not their current weight. Your vet can help you work out the right daily amount based on the food you're using. Always weigh portions with kitchen scales rather than guessing, and remember to count any treats or extras as part of the daily total.
What treats can I give my dog on a diet?
Raw carrot sticks, cucumber slices, and small pieces of apple all make great low-calorie treats. You can also use a few pieces of your dog's daily kibble allowance as training rewards. It's worth keeping treats to a small proportion of your dog's daily intake, so keep them small and be mindful of how many you're giving throughout the day.
Is my dog too fat?
Try the rib test: run your hands along their sides, and you should feel the ribs easily without pressing hard. Look from above for a visible waist, and from the side for a tummy that tucks up behind the ribcage. If any of these checks suggest extra weight, have a chat with your vet for a proper assessment.
Which dog breeds are prone to weight gain?
Labradors, Cocker Spaniels, Cavalier King Charles Spaniels, Golden Retrievers, Beagles, Pugs, and Dachshunds are all more prone to gaining weight. Labradors in particular have a known gene mutation that affects their sense of fullness. Being a predisposed breed doesn't make weight gain inevitable, but it does mean being more careful with portions and exercise.
Can I help my dog lose weight without special food?
You can make a difference by adjusting portions of their current food and cutting back on treats, but it's worth speaking to your vet about the best approach. A weight management recipe is designed to reduce fat and calories while still providing all the protein, vitamins, and minerals your dog needs, which can make the process easier to manage.
Should I exercise my overweight dog?
Yes, but start gently and build up gradually. Short walks on flat ground, increasing by a few minutes each week. Swimming is excellent for overweight dogs because it's low-impact on joints. Always check with your vet before increasing exercise, especially if your dog has joint problems or has been inactive for a while.
