Across the animal kingdom, one of the most striking behaviors observed when animals fall ill is their instinctual response to fast. Unlike humans, who often turn immediately to medications or comfort foods, animals usually cease eating and turn inward to allow their bodies to heal.

In addition to fasting, many animals also seek natural remedies – plants, minerals, or even insects – to treat specific ailments. This phenomenon offers powerful insights into the innate wisdom of nature and provides valuable lessons for human approaches to health, illness, and healing.

This article explores how and why animals fast and self-medicate, the biological mechanisms behind these actions, and how these natural strategies compare to human practices. It also explores how modern science is beginning to rediscover the value of these ancient, instinctive methods.

Fasting in the Animal Kingdom: The First Line of Defense

Why Do Animals Fast When They Are Sick?

When animals are unwell, they almost universally lose their appetite. Far from being a weakness, this is an adaptive, strategic choice governed by evolution.

• Energy Conservation: Digestion consumes energy. By not eating, animals redirect energy toward immune function and repair.
• Detoxification: Fasting allows the liver and kidneys to eliminate toxins more effectively, unburdened by continuous food processing.
• Reduced Risk of Further Contamination: Food sources may carry pathogens in the wild. When the immune system is compromised, avoiding food is a way to minimize additional threats.

Examples in the Wild

• Dogs and Cats: Domesticated animals often refuse food when sick, relying on rest and hydration. Veterinarians usually advise pet owners not to force-feed in such cases.
• Wolves and Big Cats: In the wild, predators isolate themselves and fast for days or weeks if injured or ill.
• Birds: When infected with viruses or parasites, birds exhibit lethargy and food refusal. They often perch quietly, allowing their bodies to heal.
• Reptiles: Cold-blooded animals like snakes and lizards may go weeks without eating when their metabolism slows due to illness or environmental stress.

Fasting in animals is an active biological reset not merely an absence of food. The immune system becomes more efficient, inflammation reduces, and the body enters a regenerative phase.

Zoopharmacognosy: Animals Using Natural Remedies

“Zoopharmacognosy” is the scientific term for the behavior of animals self-medicating with plants, minerals, or other natural substances. This field has opened a fascinating window into animal intelligence and instinct.

Plant Medicine in the Wild

• Chimpanzees: Jane Goodall was among the first to observe chimpanzees in Tanzania consuming the bitter leaves of the Vernonia plant when ill. These leaves have antiparasitic and antimicrobial properties.
• Elephants: Pregnant elephants in Kenya have been seen eating specific tree leaves to induce labor, suggesting knowledge of natural oxytocins.
• Parrots and Clay: Macaws in the Amazon eat clay from riverbanks to neutralize toxins in the unripe seeds they consume.
• Bears and Roots: North American bears have been observed digging up osha roots, which have antimicrobial and anti-inflammatory effects.

Insects and Natural Medicine

• Ants and Resin: Wood ants incorporate antimicrobial resins into their nests to ward off infections.
• Honeybees: Bees use propolis, a resin collected from trees, to sterilize their hives and protect against bacteria and fungi.

These actions are not learned behaviors in the traditional sense but are guided by instinct, trial-and-error, and perhaps intergenerational memory. The term “instinctive herbalism” is sometimes used to describe this phenomenon.

The Science Behind Animal Self-Healing

Modern science is uncovering how fasting and natural substances contribute to healing in animals:

• Autophagy: When animals fast, their cells initiate autophagy, cleaning out damaged components. This is now known to play a key role in preventing diseases, including cancer.
• Phytochemicals: Many plants that animals consume when sick contain powerful compounds like alkaloids, tannins, or flavonoids that have anti-inflammatory, antiparasitic, or antifungal properties.
• Microbiome Management: Natural remedies often help regulate gut bacteria, strengthening the immune system.

The success of these strategies suggests that they are not merely survival behaviors but optimized evolutionary adaptations to disease.

Human Fasting and Natural Healing: Parallels and Divergence

Humans, too, share the biological instinct to fast when sick – fever, nausea, and loss of appetite are common immune responses. However, in many cultures, this instinct is overridden by modern habits of constant nourishment and medication.

Fasting in Human Cultures

• Historical Use: Ancient Greek physicians like Hippocrates recommended fasting as a remedy for various ailments.
• Religious Practices: Fasting is used spiritually and physically in almost every religion, from Islam’s Ramadan to Buddhism’s meditation fasts.
• Modern Science: Today, fasting is being studied for its role in treating autoimmune diseases, metabolic disorders, and even cancer.

Scientific studies have confirmed many benefits of human fasting:

• Boosts immune function
• Reduces inflammation
• Triggers autophagy
• Improves insulin sensitivity
• Enhances brain function

Natural Remedies in Human Healing

While pharmaceutical medicine has largely taken over, natural remedies have a long history and are seeing renewed interest:

• Herbal Medicine: Plants like turmeric, ginger, garlic, and echinacea are known for their immune-boosting properties.
• Ayurveda and Traditional Chinese Medicine (TCM): These systems emphasize balance, prevention, and natural treatments that mirror animal instincts.
• Essential Oils and Propolis: Like bees, humans use tree resins and plant oils for their antimicrobial properties.

What Humans Can Learn from Animals

There are several key lessons humans can take from observing animals:

1. Listen to Your Body: Animals never override their body’s signals. If they’re not hungry, they don’t eat. Recognizing hunger, fatigue, and stress can help humans heal more naturally.
2. The Power of Rest and Isolation: Animals instinctively find quiet, safe places to recover. Rest is an underappreciated aspect of healing in our always-on world.
3. Minimalism in Healing: Animals effectively use one or two remedies instead of overwhelming the body with multiple drugs. Sometimes, less is more.
4. Reconnect with Nature: The natural world offers a pharmacopeia of remedies. Integrative medicine, combining modern science and natural healing, is gaining credibility.
5. Fasting as Medicine: Humans can see short-term fasting as a healing tool, under proper guidance, rather than fearing hunger during illness.

Case Studies and Observations

Case Study 1: Domesticated Dog with Digestive Illness

A Labrador retriever stopped eating for two days, drinking only water. Instead of being rushed to a vet and force-fed, the owner allowed rest. By the third day, the dog showed improvement and gradually returned to normal.

Case Study 2: Human Water Fast for Recovery

A man recovering from chronic inflammation undertook a medically supervised 7-day water fast. Blood tests post-fast showed decreased inflammatory markers and improved metabolic health.

Case Study 3: Chimpanzee Using Vernonia

Wild chimps chewing on bitter Vernonia leaves expelled parasitic worms within days. Scientists later identified active compounds that are also effective against parasites in humans.

These stories illustrate the crossover potential between animal behavior and human treatment models.

Challenges and Cautions

While there is much to learn, caution must be exercised:

• Not All Natural Remedies Are Safe: Some plants are toxic, and what works for animals may not be appropriate for humans.
• Extended Fasting Needs Supervision: Prolonged fasting should be undertaken with medical oversight.
• Respect Individual Needs: Everybody is different. What works for one may not work for another.

Balance, intuition, and scientific validation should all play roles in integrating these methods.

Conclusion: The Instinct to Heal

Nature has equipped all living beings with the tools to heal. In their unfiltered simplicity, animals show us what it means to trust the body, rest, and use the earth’s offerings wisely. Fasting and natural remedies are not outdated ideas – they are timeless strategies that modern humans are beginning to appreciate again.

By observing and honoring the innate intelligence of animals, humans can reconnect with their instincts, reclaim agency in their healing journeys, and embrace a more holistic, balanced approach to health. In the quiet of a fast or the scent of a healing herb, we find not just survival but wisdom. We see not just relief but renewal.

Ready to explore the healing power of fasting and reconnect with your body’s natural intelligence? Join us at Ananda Yoga Detox Center for a guided detox retreat rooted in nature’s wisdom.

Resources and Further Reading:

• National Institute on Aging: Autophagy and Longevity
• Jane Goodall Institute: Primate Healing Behaviors
• Journal of Ethnopharmacology: Zoopharmacognosy in the Wild
• Dr. Valter Longo: The Longevity Diet and Fasting Mimicking Diet