Ultimate Dog

By Luna Lupus - Reading Time: 11 minutes
fasting for dogs

Surprising Health Benefits of Fasting Your Dog

What you will learn in this article:

- Hidden advantages of fasting for dogs and the misconceptions surrounding this practice, tapping into its alignment with their evolutionary biology.

- Potential benefits in detoxification, cellular healing, and metabolic rejuvenation.

- Safe fasting practices, a vital aspect to consider before incorporating this technique, ensuring the best for your canine companion.

- Scientific research, offering a glimpse of the promising outcomes linking fasting to improved health in dogs.

- Diverse fasting approaches available for your dog, allowing customization based on individual needs and preferences.

- Potential transformation fasting can bring to your dog's dietary routine, promoting a shift towards a more fitting, species-specific diet.

Fasting is a common practice among people, with a lot of research backing its benefits. Being very much part of the family nowadays, dogs share our exact habitat and many of our dietary patterns. It’s natural to ask ourselves: could they benefit from fasting too? Or is the practice of fasting dogs actually cruel? This article addresses the misconceptions about fasting, safety concerns, and the incredible amount of science behind its health benefits!

Fasting vs. Starving — What Is the Difference? 

One of the biggest misconceptions (and reservations) about fasting is that it’s really just a fancy name for starving. That’s not the case. Fasting and starving trigger two very different biological processes. Fasting is based on nutritional sufficiency, meaning the body retains all of the essential nutrients for optimal health. During the fast, the dog’s body works on the principle of breaking down fat reserves for energy. The dog retains its muscle mass and looks healthy lean.

Starving, on the other hand, is nutritional insufficiency. The body lacks essential nutrients, fat reserves are depleted, important body functions begin to shut down. Malnutrition results in the body breaking down protein for energy, as that remains the only option left. This quickly leads to loss of muscle mass and all that remains on the dog are bones and skin.

In short, fasting works with the essential body functions, and starving works against them. With that said, starvation mode can occur if fasting lasts too long, so dogs should never fast more than 48 hours!

For Dogs, Fasting Is Natural 

Evolutionally, fasting is more natural to canine biology than eating every day, multiple times a day. Studying the feeding habits of wolves (who share 99% of their DNA with dogs), researchers saw that wolves often go without food for two to three days between feedings. They don’t have constant access to food, so they eat when they can catch their prey. Other wild canines are often scavengers (like coyotes and jackals), so they too have an inconsistent feeding schedule that depends on their ability to scavenge dead prey. Even though dogs are a domesticated species, they still have much of their wild biology. Through evolution, dogs have developed the digestive system of an intermittent omnivore.

You can argue that wolves and wild canines would eat every day if they had a chance. That’s true! The main question is whether daily feeding supports canine biology and positive health outcomes. Through the last century, we adapted our dogs’ diet to capitalistic standards — convenient, always accessible, calorically excessive, and often nutritionally depleted. Poor health outcomes are clear proof that we're getting something very wrong in this process.

Dogs have almost all diseases that humans have at nearly the same rates! 50% of all dogs will die from cancer, a heartbreaking statistic. 40% of dogs are obese, with this percentage getting higher every year. More dogs are suffering from cardiovascular diseases and organ failure than ever before. We have to change the way we approach feeding our dogs! Switching them to a species-appropriate diet is the best change we can make, and fasting can be part of that.

Efficient Detoxing and Cellular Healing 

When the liver can't process all of the toxins in time, they get stored as fat. As the fat accumulates in the body, so do the toxins. When dogs fast, and their body begins to burn fat for energy, the liver can start processing and eliminating those accumulated toxins again. But why does the liver need the extra help? The answer lies in metabolic and digestive enzymes.

Metabolic enzymes are the CEOs of cellular function. They’re responsible for everything that happens within trillions of cells in the body. One of the key roles of metabolic enzymes is to ensure the constant repairing and healing of cells — without this, optimum health and longevity are impossible. That’s a massive role these enzymes have! Meanwhile, digestive enzymes are responsible for the entire process of digestion. Breaking down food, turning it into fuel, aiding the absorption of important nutrients … they’re constantly in action when there’s food to be digested.

Because of the immediate task at hand, digestive enzymes take priority over metabolic enzymes. As dogs eat food every day, the process of digesting puts the process of healing, detoxing, and cell repairing on the second tier. When dogs fast, the metabolic enzymes are finally able to take precedence as the dog’s digestive tract rests. 

How to Safely Fast Your Dog 

Fasting is beneficial for healthy adult dogs. Puppies, pregnant dogs, and nursing dogs should not fast! Some dogs throw up bile (the clear yellow-ish liquid) when their stomachs are empty for too long, so they too should be excluded from fasting. It’s best to speak to your holistic veterinarian before deciding to fast your dog. They will advise you on the best type of fasting for your individual dog (based on health background, breed, and age), as well as monitor the first few weeks of the new dietary approach to see if your dog is responding to it as planned. It’s absolutely NOT recommended to go into any fast blind and just “see what happens.”

NEVER restrict your dog’s water! Healthy fasting does not include the restriction of water. Fresh drinking water must always be available to your dog to avoid dehydration, apathy, and death! 

Dogs with health issues should be evaluated on a case-to-case basis whether fasting would benefit their condition. Some conditions (such as GI disturbances) respond very well to fasting, while others (such as diabetes) may require caution and more frequent meals. Always double-check with a holistic veterinarian and a certified pet nutritionist! 

Research Links Fasting to Longer Lifespan in Dogs 

An incredible amount of research supports the benefits of fasting. Different types of fasting were studied in connection to various diseases, organs, and health outcomes. There is a common thread connecting all of this research, where all the studies eventually meet: delaying the aging process. Certain factors and diseases are known for significantly reducing the lifespan and accelerating the aging process in dogs. Weight, cancer, cardiovascular health, gastrointestinal health, and cognitive function are five such factors.

Research has linked fasting to major health benefits, specifically for these longevity markers, both in animal and human models! While these five markers are in no way the only health areas that benefit from fasting, they are the ones most closely connected with the rising early mortality in dogs.

1 — Weight Management

When we allow dogs to fast, one of the immediate results is weight loss. As their body uses excess fat for energy, dogs get a much leaner, muscular figure. Keeping your dog at a healthy weight reduces the risk of diabetes, cancer, and heart disease. One of the most remarkable studies looked at 48 Labradors throughout their lives, starting at 8 weeks and following them until death. Half of the dogs ate 25% less food than the other group. The results showed a longer lifespan (by 2 years, on average) in dogs fed the restricted-calorie diet! They weighed less, had lower body fat percentage, and the chronic diseases that developed with age were delayed, compared to the group without calorie restriction.

2 — Slowing Down Cancer 

Malignant cancerous tumors are the #1 cause of mortality in dogs. A study that looked at aging mice discovered that feeding them every other day slowed down the onset of tumor growths as they aged. Mice with unlimited access to food consequently had a shorter lifespan than fasted mice, even though the latter had a reduced caloric intake by only 7% on average! Other interesting results from this study revealed that fasted mice had lower insulin levels, consistently lower body mass, and a better immune system long-term.

3 — Resetting the Digestive System 

All dogs face digestive issues at some point in their life, with diarrhea and vomiting being the two most common symptoms. Veterinarians often recommend a temporary diet of cooked rice and plain protein (mostly chicken or fish) until the symptoms subside. But dogs are biologically adapted to handle a scavenger lifestyle, so their digestive tract knows how to deal with an occasional bad food choice.

Vomiting and diarrhea are a sign of the body trying to clear out what disrupted it in the first place. This is why fasting for 24 hours after the onset of digestive symptoms is a better intervention than quickly changing the diet. We should allow the dog’s body to heal from the digestive disruption by letting his digestion rest and reset! Fasting “resets” the digestive system by giving it time to clear itself, engage the healing function of metabolic enzymes, and begin with a clean slate once the food starts to be reintroduced.

4 — Protecting the Heart 

Animal studies have shown that fasting lowers blood pressure and resting heart rate within a week of implementing the fast! When looking at the cardiovascular system of intermittently fasted rodents, scientists were surprised to see that intermittent fasting affected the heart similarly to aerobic exercise. The conclusion on intermittent fasting is that it’s cardioprotective. As dogs age, their risk for cardiological issues rises. Intermittent fasting can protect their heart in their senior years and so contribute to a greater quality of life and a longer lifespan overall.

5 — Supporting Cognitive Function

Cognitive decline is common in elderly dogs and can be heartbreaking for the owners to witness. Several different types of fasting have shown incredible potential in slowing down cognitive decline and protecting neurological functions. Some studies looked at how fasting affects Alzheimer’s and Parkinson’s disease in animals and found that intermittent fasting supports cognitive function in animals with these neurological diseases. Other animal studies showed that fasting increases the brain’s functionality and response to stress, even in the cases of traumatic brain injury or stroke! As your dog’s brain ages, the neurological benefits of fasting become indispensable. 

Different Ways of Fasting Your Dog 

Researchers looking into fasting have studied a whole variety of fasting methods. The main consensus seems to be that any type of fasting has health benefits. What all of the different types have in common is a lower calorie intake and allowing digestion to rest for a certain amount of time. Where they differ, however, is in the length of those fasting timeframes. A holistic veterinarian or a certified pet nutritionist should help you choose the right kind of fast for your dog! These are the most popular options: 

  • Fasting for 24 hours between meals. This is probably the most convenient option, easily achieved by feeding your dog only once a day rather than twice.
  • Fasting once or twice a week. Allow your dog’s digestion to rest by skipping one full day of feeding or one daily meal on fast days (if you’re regularly feeding your dog twice daily).
  • Fasting for 16-18 hours overnight. This is the most common way of intermittent fasting. When you fit your dog’s daily meals into a timeframe that doesn’t exceed 6-8 hours, their body can fast for the remaining 16-18 hours of the day, most of which take place overnight. 
  • Restricted calorie intake is an alternative for dogs unable to fast. Instead of skipping meals in certain timeframes, you can reduce your dog’s caloric intake by up to 25%, depending on professional advice.

Fasting Fits Into Every Diet 

In our endless pursuit of convenience, the modern canine diet is shaped around human needs (conserving time, low price, zero thinking) rather than the dog’s nutritional needs. Fasting appeals to both sides. It’s species-appropriate and promotes long-term health, but it’s also easy to do, doesn’t cost anything, and doesn’t require extra time. Dogs on any diet, processed or fresh, can benefit from fasting! Perhaps it’s especially the dogs who have spent most of their life on processed food who need digestive rest the most. 


Becker, Karen. “Therapeutic Fasting – This Dietary Habit of Wolves Might Be Right for Your Dog Too But Never for a Cat.” Healthy Pets, 06/10/2011. 

Devereaux, Johnna. “How Fasting Can Help a Sick Pup.” Fetch Ri, 25/01/2022. 

Kangas, B. Katie. “Intermittent Fasting – Can It Help Dogs Stay Healthier and Live Longer?” Animal Wellness, 15/11/2022. 

Xie K, Neff F, Markert A, et al. “Every-other-day feeding extends lifespan but fails to delay many symptoms of aging in mice.” PubMed, 24/07/2017.

Mattson, P. Mark. Longo, D. Valter. Harvie, Michelle. “Impact of intermittent fasting on health and disease processes.” Science Direct, 10/2017. Kealy, Richard. Lawler, Dennis. Ballam, Joan. et al. “Effects of diet restriction on life span and age-related changes in dogs.” Research Gate, 06/2002.

Luna Lupus

Luna’s passion for learning about canine psychology and behavior began when she adopted a severely reactive puppy from a local shelter. She is now a big advocate for positive reinforcement and compassionate training. As a writer, she strives to spotlight the topics that fly under the radar and be the voice for all who cannot speak for themselves.

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