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October 6, 2020 – Turn on the television, browse the internet, or listen to the radio, and stories about the obesity epidemic are everywhere. According to the Centers for Disease Control, an estimated 70% of adults are obese or overweight and the statistics are almost as bad for our pets. The Association for Pet Obesity Prevention reports that, according to its 2018 data, a staggering 56% of dogs and 60% of cats in the United States are overweight or obese.

Losing weight, whether for ourselves or our furry friends, can be a challenge and for good reason. Mounting evidence shows that body weight is regulated by a complex interplay of hormones, psychological factors, environmental influences and genetics, each contributing in some way to weight gain and loss. Knowing more about these factors can help owners manage weight loss in their pets successfully.

New theories on the how and whys of overweight pets

Although the basic equation of excess energy intake versus expenditure is still valid when it comes to weight gain, other factors also appear to play a role in the development and maintenance of obesity, or overweight, body condition. These include:


A tendency towards obesity might be inherited. Studies suggest that Labrador retrievers have the highest obesity prevalence, and research performed in the United Kingdom found that a genetic mutation was associated with overweight or obese Labrador retrievers as well as flat-coated retrievers. Interestingly, the mutation was more common in dogs from service dog lineages. The research team theorized dogs that were more food motivated were easier to train as service dogs, which in turn perpetuated obesity. The team now is looking at other breeds for genetic mutations that might account for a tendency toward obesity, including using samples from the Foundation’s Golden Retriever Lifetime Study.

Breed standards

Additional studies from the Netherlands showed a strong breed predisposition in both dogs and cats toward being overweight. Researchers proposed that not only genetics, but breed standards (ideal characteristics and appearance of a breed) could explain why certain breeds tend to be overweight. In other words, certain breed standards could be linked to obesity or promote a heavier body condition. More research needs to be done in this area, but this team suggested that breed organizations scrutinize their current breed standards and make adjustments, as necessary.

Gut bacteria

Interest in the gut microbiota (the community of organisms residing in the gut) has exploded in the last decade in both human and veterinary medicine. Several studies have linked increased body weight to changes in the gut microbiome (the sum of all the genetic material in the gut). Veterinary researchers have documented a difference between the composition of the microbiome of obese and overweight individuals and their leaner counterparts. Studies on the cat microbiome also indicate differences between the microbiomes of obese and lean individuals.  However, the question remains as to if the gut bacteria change occurs prior to an animal becoming obese (and could be driving the weight gain) or changes after a dog or cat gains weight (and could possibly be perpetuating the weight gain).

Intriguing studies in mice show that giving fecal transplants from the gut of lean mice into obese mice appears to lead to weight loss in obese mice, and the opposite also appears to be true. As we learn more about the interplay between the gut microbiome and the development of obesity, the possibility of manipulating the resident microbes in the gut to assist in weight loss is a tantalizing concept. In the future, it may be possible to administer either a fecal transplant or an oral probiotic mixture to overweight animals to facilitate weight loss.

Re-setting a weight thermostat?

Weight loss, whether it is in our pets or ourselves, is difficult to maintain. Scientists are finding that our bodies have a certain weight thermostat, and that in the face of weight loss (or even gain), our body will attempt to maintain a consistent weight. Although this effect often protects us from becoming overweight, the thermostat can get re-set to an overweight or obese condition, impacting our ability to achieve or maintain weight loss. Learning how to set the thermostat to maintain a leaner body type is the subject of ongoing study in people and ultimately could help our pets as well.

Many factors beyond diet contribute to obesity in pets

It’s no surprise many factors contribute to obesity. For example, a study published in 2010 looked at environmental risk factors associated with canine obesity. Researchers found that increasing owner age, decreased weekly exercise hours, and lower owner income levels were all associated with a higher risk for pet obesity. The researchers concluded that in their study, owner-related factors were more important in the development of obesity than dog-related factors such as breed, age or reproductive status.

Studies show many owners underestimate their pet’s body condition, leading to the misperception that their pets have a normal body condition when they’re actually overweight. The good news here is there are several validated body condition charts that are easy for veterinarians and owners to use. Many veterinary clinics now include this as part of their physical examination and often share these resources with clients to help them recognize when weight in their pet is becoming a problem.

Pet owners contribute to the overweight/obesity problem in other ways, too. A survey conducted from owners of obese and overweight dogs in the United Kingdom showed that pet owners had a variety of justifications for their dog’s body conditions, including the use of food to show affection, preferring that their pet was happy even if it meant a shorter life, and denial that their pet was overweight at all. Changing attitudes and behaviors can be a high hurdle for a veterinary team.

Veterinarians are uncomfortable talking about weight issues with clients

Discussing weight loss with pet owners can be difficult and a recent review on how to effectively talk to owners about weight loss indicates it makes veterinarians feel uncomfortable. The review noted that veterinarians feel that they will “offend, upset, anger, or even lose a client,” if they bring up the subject of a pet’s weight. If the owner or the veterinarian is overweight, the situation is even more strained. No wonder many veterinarians avoid even discussing the subject with their clients!

The same review suggested enlisting the entire veterinary team to deliver consistent and clear messaging regarding weight loss. They found that keys to successful weight loss include continuous, active engagement with owners, and tailoring weight loss strategies to fit both the pet and owner’s lifestyles.

Pet weight loss programs fail for many reasons

Weight loss programs fail for pets for many reasons. Attitudes toward pet feeding and even body conformation assessment can influence whether a pet owner adheres to a pet’s weight loss program, or even recognizes a need for weight loss.

Adhering to a weight loss plan can be challenging for owners. A study recently demonstrated that in a group of obese dogs referred to a weight loss program, approximately 32% dropped out before reaching their weight loss goals. The researchers couldn’t pinpoint a single cause for the dogs’ failure rate, but commonly cited reasons for dropping out included difficulty adhering to weight loss plans, lack of ongoing support and development of other illnesses that shifted the owner’s focus.

Another interesting project was originally designed as a weight loss and feeding strategy study, but the study team found something else. The researchers divided the test subjects into three groups, each assigned different diet strategies: feeding a high-fiber diet on demand; feeding a high-fiber diet that required the owners to measure out food portions; and feeding a pre-portioned combination of canned and dry food. Although there were no differences in weight loss between the groups, the researchers were surprised to find that owners were most dissatisfied when they had to measure the food portions themselves. They reported greater hunger in their pets and noted accompanying behavioral changes (such as increased vocalization). The team concluded that convenience and related owner perceptions of hunger behaviors could influence compliance when instituting a weight loss program.

Strategies to improve weight loss success

Obesity remains one of the few diseases that pet owners can influence, but it’s a journey that can take many months. Maintaining weight loss requires vigilance.

Switching a pet to a prescription diet that promotes weight loss remains one of the best and easiest ways to help a pet lose weight. Although many commercial foods are advertised as weight reduction or light diets, these products often are not as effective as prescription diets in promoting weight loss. The downside is prescription diets require a veterinarian’s recommendation and almost always more expensive then diets purchased in most pet food stores.

One study conducted with dog owners in the United Kingdom compared prescription-diet fed exclusively and a regular commercial diet plus treats. The researchers found that costs were roughly similar when they looked at the average spent. However, there was a very wide range in costs per dog, with some food costs much lower than prescription diet and some food costs much higher. This study’s finding is important because it demonstrated that at least in some cases, feeding the prescription diet was less expensive than commercial food.

Other weight loss strategies include:

  • Giving pets plenty of exercise and social stimulation.
  • Using food puzzles for feeding – these slow consumption while providing stimulation.
  • Thoughtful timing of spaying and neutering.
  • Using a consistent measuring device (measuring cup or scale) to determine portions.
  • Avoiding high-calorie (especially high-fat) treats, even in small amounts.
  • Enlisting the support of the entire veterinary care team.
  • Avoiding assigning blame and engaging everyone in the family to help.
  • Being patient – weight loss is hard!

It’s important to talk to your veterinarian before starting any weight loss and exercise program for your pet. Your veterinarian can help guide the program and provide resources to ensure success!