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Weight Gain In Dogs: Why Is My Dog Gaining Weight?

Written by: Molly Weinfurter
Molly Weinfurter is a writer for iHeartDogs, and she’s passionate about helping animals in need. She volunteers for Bailing Out Benji and a local dog rescue.Read more
| Published on February 20, 2024
iHeartDogs is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no extra cost to you.

Weight gain in dogs is one of the most common health concerns among dog parents. Overweight dogs may also experience other health concerns as a result, so keeping your dog at a healthy weight is crucial to their well-being. However, you need to find the cause of your dog’s weight gain to implement an effective solution. Always start by visiting your vet to rule out any illnesses that could cause weight gain, and ask your vet for the best diet and exercise recommendations to keep your pup a healthy weight.

Dog getting weighed

Weight Gain in Dogs: When Should I Worry About My Dog’s Weight?

Gaining a pound or two might not be a huge concern for most dogs, but if weight gain is paired with other issues, such as lethargy or digestive problems, it’s best to seek veterinary advice right away. Other causes for concern are rapid weight gain over a short period, sudden disinterest in exercise, unusual eating habits, or a change in body condition score.

What is Body Condition Score in Dogs?

Body condition score (BCS) is a common method for evaluating a dog’s body fat. It’s usually on a scale from 1-5 or 1-9 with images beside each number (1-9 is usually more common). You can look at the images to decide which one looks closest to your dog’s shape. A weight in the middle of the chart is typically the healthiest, but your vet can talk to you about whether your dog needs to gain or lose weight.

BCS 1-9 Scale:

  • 1/9: Emaciated
  • 2/9: Very thin
  • 3/9: Thin
  • 4-5/9: Ideal Weight
  • 6/9: Overweight
  • 7/9: Heavy
  • 8/9: Obese
  • 9/9: Severely Obese

The details of the chart can vary slightly, but 4-5 is typically a healthy body condition to aim for. If your dog is an ideal weight, you should be able to feel their ribs without the bones being easily visible. Vets can answer any questions you have about the BCS numbers.

Body Condition Chart for dogs

What Breeds Are at Risk?

Any dog can become obese, but here are some breeds that are at a higher risk:

  • Basset Hounds
  • Beagles
  • Bulldogs
  • Cocker Spaniels
  • Dachshunds
  • Golden Retrievers
  • Labrador Retrievers
  • Pugs

Even though some breeds can gain weight more easily than others, their lifestyle matters the most. Make sure you’re managing your dog’s diet and exercise well, and always talk to your vet if you need advice on how to keep your pup healthy.

What Causes Weight Gain in Dogs?

Weight gain can happen for a variety of reasons, including the following. However, you need to talk to your vet to determine the exact cause.

Issues with Diet and/or Portions

Overfeeding is a common cause of pet weight gain. The portion charts on dog food bags are only a suggestion, so following them blindly could cause you to feed your dog too much. After all, those serving suggestions don’t always take into account your dog’s energy levels and diet goals. Your vet can help you determine if your dog’s portion size is correct based on their individual needs.

If you free-feed your dog, that’s another way for them to easily gain weight. Dogs who always have access to food may eat more than they need throughout the day, and it can be difficult to track how much they typically eat. So, only offering food for 15-20 minutes and then taking it away if they don’t eat it can help them get used to eating on a specific schedule.

In some cases, the portions could be fine, but the food may not be as healthy as you’d like. Consider switching to a weight management formula like Nutro Healthy Weight to keep your pup in shape. Personalized fresh food plans like Nom Nom can also be a good choice because you need to fill out a questionnaire to get the servings customized to fit your dog’s needs. Again, whenever you’re unsure about your dog’s diet, ask your vet for personalized advice.

Dog food weight gain

Too Many Treats

It’s hard to say no to the adorable eyes of a begging dog, but doing so could extend your pup’s lifespan. Treats should make up no more than 10% of your dog’s daily calories. If you give your dog table scraps as treats, there’s a good chance they’re getting more daily calories than needed. Plus, too many treats can make dogs less interested in their meals, which can prevent them from getting some of the nutrients they need.

To ensure your dog is getting a healthy amount of treats, avoid giving table scraps and opt for low-calorie treats. Healthy treats could include plain fruits and vegetables like blueberries and carrots or training treats that are specifically made to be low in calories. Buddy Biscuits Trainers and Zuke’s Mini Naturals are great treats because they each have two or fewer calories per treat.

Not Enough Exercise

Even if your dog has a healthy diet that’s perfect for their age and lifestyle, they can still gain weight without proper exercise. Dogs should get a bare minimum of at least 20 minutes of exercise per day. That activity can be as simple as a walk around the block or a game of fetch. However, if your pet hasn’t had much exercise lately, you should start small instead of going on a mile run right away. Dogs need to be eased into an exercise routine just like humans do.

When walking your dog, make sure you have durable walking gear to keep them comfortable and safe. A strong leash that won’t fray, such as the Atlas Pet Lifetime Leash, and a no-pull harness, such as the Rover Gear Better Walk Harness, can make exercise sessions more comfortable for dogs of all sizes.


Anxious dogs may develop unhealthy habits that lead to weight gain. Sometimes, dogs eat more and/or exercise less when they’re feeling stressed. If your dog is gaining weight after a sudden lifestyle change, stress could be the cause. Your vet can help you find ways to help your anxious pup relax.

Overweight Dachshund


Dogs with internal parasites might experience sudden weight gain. Some parasites can attach themselves to the abdominal walls and the intestines, leading to infections and fluid buildup. In those instances, dogs may appear more bloated than usual, even if they’re eating and exercising normally. Your dog will likely display other unusual symptoms, too, but the vet can run a test to find out if parasites are to blame.

Joint Pain

When a dog is overweight, it can lead to joint pain. However, a dog of a healthy weight can also gain weight because of joint pain. If your dog experiences pain or discomfort when trying to exercise, they may avoid intense activities. With less exercise, they’re less likely to maintain a healthy weight. If you notice limping, stiffness, lethargy, loss of appetite, or licking/chewing a specific area, your dog might suffer from joint pain.

To determine that joint pain is what’s causing your dog’s reluctance to exercise, talk to your vet. If your vet agrees that your dog is dealing with joint issues, you should try giving them a joint supplement to ease their pain. Even if your dog hasn’t dealt with mobility issues yet, giving them a regular joint supplement can reduce the risk of joint problems in the future.


Other illnesses, such as Cushing’s disease, hypothyroidism, and bloat, could lead to sudden weight gain in dogs. Thus, if your dog has experienced unexpected weight gain recently, it’s best to visit the vet first to rule out any underlying health concerns.

Very overweight Pug

Why Dog Weight Gain Can Be Dangerous

Obesity affects more than just your dog’s appearance. If your dog is overweight, they could be at a higher risk of the following health conditions:

  • Arthritis
  • Diabetes mellitus
  • Heart disease
  • Cancer
  • Respiratory issues
  • Hypertension
  • Liver disease
  • Urinary tract issues
  • Skin problems
  • Immune system issues
  • Anesthetic complications

All the above conditions could shorten your dog’s lifespan. So, keeping your dog a healthy weight is a great way to reduce the risk of serious health concerns, which can help them live a longer, happier life.

Frequently Asked Questions

What is Considered a Healthy Weight for Dogs?

A healthy weight for dogs varies depending on their breed, age, and individual characteristics. Generally, a healthy weight is one where the dog has a body condition score (BCS) of around 4 to 5 on a scale of 1 to 9, with one being emaciated and nine being obese. Dogs at a healthy weight typically have a well-defined waist when viewed from above, and their ribs can be felt but not seen.

Why is My Dog Suddenly Putting on Weight?

Sudden weight gain in dogs can be caused by various factors, including overeating, changes in diet, reduced exercise, and certain medical conditions such as hypothyroidism, hormonal imbalances, or gastrointestinal problems. In an unspayed female, sudden weight gain could be because of a pregnancy. It’s essential to consult with a veterinarian to identify the underlying cause before coming up with a plan to manage it.

Why is My Dog Getting Fat But Not Eating?

If your dog is getting fat but not eating, it could be due to a decrease in physical activity or a slower metabolism. In some cases, medical conditions like hypothyroidism or Cushing’s disease may be the underlying cause, as they can affect a dog’s weight despite a reduced appetite. It’s important to consult a veterinarian to determine the cause and address potential health issues.

Can Cancer Cause Weight Gain in Dogs?

Yes, cancer can potentially cause weight gain in dogs, but it’s more common for cancer to lead to weight loss or changes in appetite. Certain types of tumors, such as those associated with the endocrine system, can disrupt hormones and metabolism, potentially resulting in weight gain. However, unexplained weight changes in a dog, whether gain or loss, should always be promptly evaluated by a veterinarian.

Do Dogs Gain Weight After Being Spayed/Neutered?

Spaying or neutering itself does not directly cause weight gain in dogs. However, the reduction in sex hormones can lead to a decrease in metabolic rate and may result in a tendency to gain weight if the dog’s diet and exercise are not appropriately managed. To prevent post-spay/neuter weight gain, it’s important to adjust the dog’s diet and exercise routine to match their reduced energy needs and monitor their weight regularly.

Overweight Labrador outside

Final Thoughts

Weight gain in dogs can lead to severe health concerns if not properly managed. So, if you notice your dog gaining weight, take them to the vet to determine the underlying cause. Then, you can come up with a personalized weight loss plan with the help of your veterinarian. Dogs are part of the family, so we need to help them live long, happy lives by keeping them as healthy as possible.

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