Diet trends come and go, and intermittent fasting has become popular for weight loss in people. While research suggests it can be safe and effective for humans, the same doesn’t automatically apply to dogs. Intermittent fasting in dogs isn’t well studied and may carry risks, especially without veterinary supervision. If your dog is overweight, it’s best to consult your veterinarian before making any changes to their feeding routine.
In This Article
What Research Shows About Fasting in Dogs
Intermittent fasting in people can involve skipping meals during certain hours or on specific days. In dogs, however, the concept hasn’t been extensively researched, and much of the discussion is based on observation rather than strong scientific evidence. “These are mostly anecdotal reports and not scientific studies,” notes Dr. Jerry Klein, DVM, Chief Veterinarian for the American Kennel Club.
Since hospitalized dogs are at risk of underfeeding and depressed immunity, researchers conducted a study on the effects of intermittent fasting on immune health in healthy dogs only. One small study involving 10 healthy dogs compared different feeding schedules. Dogs in a fasting group lost more weight and showed lower blood glucose and insulin levels. However, the study was limited in size and only included healthy animals, so the findings can’t be broadly applied. Importantly, fasting didn’t appear to suppress immune function in this controlled setting.
Another source of data comes from the Dog Aging Project, which has tracked more than 24,000 companion dogs since 2019. Early findings suggest dogs fed once daily had fewer reported health issues, including gastrointestinal, dental, kidney, and liver conditions. Although these findings differentiate dogs by feeding frequency, the reduction in health problems cannot be attributed solely to that factor. More research is needed to establish a direct cause-and-effect relationship between once-daily feeding and improved health, versus other contributing factors.
Why Dogs Don’t Follow Wolf Feeding Patterns
Although dogs share ancestry with wolves, their dietary needs and feeding routines have changed over time. Wolves often go long periods without food due to hunting patterns, which can make fasting seem natural. But domesticated dogs evolved in environments where food was more consistent.
As dogs adapted to living alongside humans, their digestive systems also changed. “Dogs have the ability to digest certain carbohydrates that wolves generally do not,” says Dr. Klein. “The environment of dogs has allowed the adaptation of their gut microbiota to handle a starch-rich diet.”
These differences mean that feeding patterns modeled after wolves may not be appropriate for modern dogs.
When Veterinarians May Recommend Temporary Fasting
You should only fast your dog after consulting your veterinarian and being advised to do so. For example, if a dog is experiencing gastrointestinal distress like vomiting or diarrhea, a short fasting period may help the digestive system recover.
In these cases, a veterinarian might recommend withholding food for 12 to 24 hours while allowing access to water. As Dr. Klein explains, this gives the gastrointestinal tract time to rest and heal. As your dog’s condition improves, you can gradually reintroduce food, staring with bland options like pumpkin or plain boiled white rice.
Regardless of their feeding regimen, your dog always needs access to fresh drinking water. Dr. Klein explains that dogs are more likely to suffer ill effects and die from dehydration than malnourishment.
Which Dogs Should Not Be Fasted?
Fasting isn’t suitable for every dog, and in some cases it can be harmful. Dr. Klein advises that intermittent fasting “should only be considered in healthy, adult dogs,” and always with professional input.
He advises consulting a veterinarian or a board-certified veterinary nutritionist. A professional can help determine whether fasting is necessary or the right approach for your dog. That said, intermittent fasting is not appropriate in the following situations:
- Puppies under 18 months, especially large or giant breeds
- Very small or Toy breeds, such as Chihuahuas or Yorkshire Terriers
- Pregnant or nursing dogs
- Dogs with underlying medical conditions, such as diabetes
For these dogs, consistent nutrition is critical to support growth, energy levels, and overall health.
A Safer Approach to Managing Your Dog’s Weight
Maintaining a healthy weight is an important goal for many dog owners, but fasting is rarely the first or best solution. Instead, focus on proven strategies that support long-term health.
“Appropriate daily feeding, using minimal low-calorie treats, avoiding table scraps, and exercising them regularly [is best],” Dr. Klein explains, “rather than having to resort to fasting.” For adult dogs engaged in normal activities, you can consider feeding them once a day.
Although intermittent fasting is having a resurgence among people, there are risks when we apply these dietary practices to our dogs. “Dogs have different metabolisms and nutritional requirements than people and most other animals,” Dr. Klein says. His advice is to feed your dog a complete and balanced diet as directed by your veterinarian and the dog food’s label.
Key Takeaways
- Intermittent fasting in dogs lacks strong scientific evidence and isn’t widely recommended.
- Small studies show possible metabolic changes, but results are limited and not conclusive.
- Short-term fasting may be used for medical reasons under veterinary supervision.
- Portion control, proper diet, and exercise are safer ways to manage a dog’s weight.
- Homemade diets are not suitable for growing puppies without expert supervision
Frequently Asked Questions
-
Can intermittent fasting help my dog lose weight?
+
There’s limited evidence to support this approach in dogs. Safer options include portion control, balanced nutrition, and regular exercise, guided by your veterinarian.
-
Is feeding a dog once a day the same as fasting?
+
Not exactly. Feeding once daily is a different schedule, and while some data suggest potential benefits, it’s not conclusive and should be discussed with your veterinarian.
-
How long can a dog go without eating?
+
Healthy adult dogs may tolerate 12 to 24 hours without food under veterinary guidance. Longer or unsupervised fasting can be risky.
-
When is fasting helpful for dogs?
+
Short-term fasting may be recommended for digestive issues like vomiting or diarrhea, but only under veterinary supervision and with access to water.