Fasting– people have been doing it since the dawn of time. Our ancient ancestors didn’t readily have access to food and their bodies had to rely on their fat stores to carry them through to when food was available. Various religions observe periods of fasting, the ancient Greeks fasted for mental clarity.
People purportedly recount how they feel mentally sharper and clearer when fasting.
Fasting, though, is not promoted as a health enhancer since the concept does not generate money- hence the pervasive counter arguments against it. We are taught that we must eat at every mealtime or face irreparable harm.
These myths include the premise that one will become hypoglycemic if blood sugar drops (false- your body’s need for glucose is reduced) and also- the notion that starvation will cause muscle loss. Again, the body has adapted to periods of controlled fasting (starvation for our ancestors) so there is a mechanism our bodies use to not lose lean muscle- we store 24-36 hours of enough glucose in our liver, and beyond that we adapt to burning fat for energy. Why would we have evolved to store fat for energy if we were to burn carbohydrates/protein instead? If our bodies continued to burn lean mass for 5 days we would die, which is obviously not the case- think Kalahari bushmen, Native Americans and Aboriginals who go long periods without food. Breakdown of muscle tissue occurs at extremely low levels of body fat- approximately 4%.
Another myth is that our brain needs 130 mg/day of glucose which is flagrantly wrong- our brains use ketones (the by-product of fat when it is broken down for energy) as a preferred energy source, thus allowing for conservation of skeletal muscle.** People purportedly recount how they feel mentally sharper and clearer when fasting.
Now, regarded as a modern concept for weight loss, it is much more than that. Fasting has innumerable benefits for people in varying states of health. The hot topic of fasting and anti-aging relates to the concept of eliminating old cells and building anew with new cells. This concept called autophagy – processes by which your body cleans out toxins and damaged cellular components- is activated by a fasting state. With this, skin improves and tightens as it is protein. This discards a prevailing notion that more and more protein on the old foundation (no cleaning out with fasting) is actually detrimental. Too much protein can be a bad thing.
Other benefits to fasting include:
- increased counter regulatory hormones- HGH (human growth hormone) which promotes laying down lean mass when one eats again, and hormone noradrenaline which increases energy and keeps metabolic rate high
- lowers triglyceride levels
- suppresses inflammation
- normalizes the hunger hormone ghrelin
- promotes insulin sensitivity
Fasting can be any duration you want (Dr. Jason Fung chooses a 24 hour window- dinner to dinner a few times a week). The most important thing to remember when adopting a lifestyle that includes regular fasting periods is that it must fit into your lifestyle- it cannot interrupt or change your life.
Best practice for me that yielded comfortable results- more than about losing weight, but rather feeling clean and energetic-is an ongoing compressed window of time to eat. I like to have my last meal of the day by 6-7pm and then a large lunch around 11am the next day. So approximately 15-16 hours of a fast. I find that I exercise better in the morning as I’m lighter and using fat as an energy source rather than glucose that I need to immediately replenish to feel ok.
**Sources: Dr. Jason Fung (nephrologist) in his book The Obesity Code and his website, Intensive Dietary Management
Dr. Mercola http://www.mercola.com/infographics/intermittent-fasting.htm