Intermittent fasting has become very popular among humans. In recent years, this practice has also raised questions among dog owners: can it improve their health or longevity?

The answer is more nuanced than one might think.

Studies do exist in dogs, but not all of them focus on intermittent fasting. Some evaluate caloric restriction, others meal frequency. These two approaches are often confused, even though they do not address the same question.

The strongest evidence: caloric restriction

The reference study is by Kealy and his colleagues, conducted throughout the lives of 48 Labrador Retrievers.

Dogs receiving approximately 25% fewer calories than their counterparts, while maintaining a balanced diet, lived on average nearly two years longer. They also developed several age-related diseases, particularly joint problems, later in life.

An analysis published several years later confirmed these results: maintaining a dog at a healthy weight throughout its life is associated with a longer life expectancy and a later onset of chronic diseases.

It is important to emphasize that this work focuses on controlled caloric restriction, not intermittent fasting.

One meal a day: an interesting association

In 2022, the Dog Aging Project analyzed data from over 24,000 dogs.

Dogs fed only once a day had fewer cognitive disorders and a lower frequency of certain digestive, dental, orthopedic, kidney, urinary, liver, and pancreatic diseases than those receiving multiple meals.

Thanks to its very large number of participants, this study is now the main reference when it comes to meal frequency in dogs.

A study that does not prove an effect of a single meal

However, this study remains observational.

In other words, it highlights associations but does not demonstrate that feeding a dog only once a day directly improves its health.

The authors themselves point out that a sick dog is often fed more frequently, which may explain some of the observed results.

Furthermore, medical information largely comes from owners and not from a standardized veterinary examination performed on all dogs.

These limitations do not invalidate the study, but they require caution in its interpretation.

What do we really know about intermittent fasting?

To date, no high-quality clinical trial has demonstrated that an intermittent fasting protocol directly improves dog health or longevity.

Current knowledge is mainly based on three elements:

• caloric restriction, which has shown a benefit on longevity;
• studies on meal frequency, which highlight interesting associations;
• biological mechanisms well described in other species, but still little studied in dogs.

Intermittent fasting therefore remains a promising avenue of research, but not a practice whose benefits are currently proven.

A single meal is not suitable for all dogs

Giving only one meal a day is not suitable for all situations.

In large and giant breeds, several studies have shown that a single, large volume meal increases the risk of gastric dilatation-volvulus (GDV). This veterinary emergency occurs when the stomach becomes severely distended and can then twist upon itself, preventing blood circulation and the evacuation of gases.

For these dogs, dividing the ration into several meals is generally considered safer.

A single meal or intermittent fasting are also not recommended without veterinary advice for:

• puppies;
• pregnant or lactating bitches;
• diabetic dogs;
• dogs with digestive diseases;
• very thin, fragile dogs or those with a chronic illness.

Key takeaways

Currently, the strongest evidence regarding dog longevity does not concern intermittent fasting, but maintaining a healthy weight through moderate caloric restriction when necessary.

Daily single meals are associated with better health indicators in a large observational study, but this association does not prove that it directly improves the health of dogs.

Intermittent fasting therefore remains an interesting hypothesis, but it is not sufficiently proven to be generally recommended. Any significant dietary change must consider the dog's age, breed, health status, and lifestyle.

Sources

1. Kealy, R. D., Lawler, D. F., Ballam, J. M., et al. (2002). Effects of diet restriction on life span and age-related changes in dogs. Journal of the American Veterinary Medical Association, 220(9), 1315–1320.
2. Lawler, D. F., Larson, B. T., Ballam, J. M., et al. (2008). Diet restriction and ageing in the dog: major observations over two decades. British Journal of Nutrition, 99(S1), S21–S31.
3. Bray, E. E., Lepine, S. E., Larson, B. T., et al. (2022). Once-daily feeding is associated with better cognitive function and health in companion dogs: Results from the Dog Aging Project. GeroScience, 44, 1909–1923.
4. Raghavan, M., Glickman, N., McCabe, G., et al. (2004). Diet-related risk factors for gastric dilatation-volvulus in dogs of high-risk breeds. Journal of the American Animal Hospital Association, 40(3), 192–203.
5. Glickman, L. T., Glickman, N. W., Schellenberg, D. B., et al. (2000). Multiple risk factors for the gastric dilatation-volvulus syndrome in dogs. Journal of the American Animal Hospital Association, 36(3), 217–225.