Fasting is often misunderstood, with many assuming it slows down metabolism and causes fatigue. However, Dr. Jason Fung, a prominent advocate for intermittent fasting, explains that the reality may be quite different. In his appearance on the Diary of a CEO podcast, Dr. Fung discusses how fasting affects the body, challenging common beliefs about food and energy.

Fasting Boosts Energy, Not Fatigue

Contrary to popular belief, fasting does not slow down metabolism. Dr. Fung clarifies that when you stop eating, your body begins to use stored calories for energy, which actually boosts your metabolic rate rather than decreasing it. “As your insulin levels drop, other hormones such as growth hormone and cortisol rise, which helps increase your energy levels,” says Dr. Fung. This challenges the common idea that fasting makes you sluggish.

Fasting and the Fight-or-Flight Response

During fasting, the body enters a heightened state of alertness, known as the fight-or-flight response. Dr. Fung points out, “Hungry animals are more dangerous because their bodies are in an activated state, ready to hunt for food.” This physiological reaction, triggered by increased cortisol and growth hormone, enhances the body’s ability to efficiently utilize stored energy.

Health Benefits Beyond Weight Loss

Research from Cambridge University supports the idea that fasting offers more than just weight loss benefits. A 24-hour fast can reduce harmful inflammation in the body by raising levels of arachidonic acid, a crucial fatty acid. This has potential implications for lowering the risk of chronic diseases such as Alzheimer’s and Parkinson’s. Professor Clare Bryant of the University of Cambridge adds, “Our work adds to the growing evidence that calorie restriction has broad health benefits.”

Fasting and Brain Health

Fasting also appears to have positive effects on brain health. By reducing inflammation and increasing arachidonic acid levels, fasting may offer protection against neurodegenerative diseases. However, researchers caution that more studies are needed to fully understand these long-term effects. This emerging field of science suggests that fasting could be a simple approach to maintaining cognitive health as we age.

The Breakfast Debate: To Eat or Not to Eat?

While Dr. Fung advocates fasting, not all experts agree with skipping breakfast. Nutrition therapist Justin Nault warns that missing breakfast could signal metabolic issues. He argues that breakfast is essential for kickstarting metabolism and preventing unhealthy metabolic adaptations. The NHS also advises against skipping breakfast, highlighting its role in supporting overall health.

Should You Try Fasting?

If you're considering fasting, it’s crucial to consult with your doctor first. While fasting offers health benefits, it may not be suitable for everyone. “Don’t change your lifestyle based on what someone on the internet recommends,” Dr. Fung advises. Understanding the science and its effects on your body can help you make an informed choice about whether fasting is right for you.