The Health Benefits of Intermittent Fasting

The benefits of intermittent fasting (IF) extend far beyond fat loss. Research dating back to the 1930’s shows that groups who eat less live longer. From an evolutionary perspective, it sure seems the human body is designed for periodic fasting.  Our ancestors weren’t able to consume the same amounts of food at regular intervals each day, as 21st century dieters are usually instructed to do.  The food intake of our forebears was based on what was available and that supply was unpredictable. Evolution occurs over a period of tens of thousands of years.  We still have the same genes as our primitive ancestors.  So our bodies haven’t yet adapted to the constantly fed state that we’ve forced upon them.

Physiologically, we can easily handle the intermittent fasting approach because it goes back to our ancestors’ eating patterns, when food wasn’t continually available,” Mark P. Mattson, Ph.D., senior investigator for the National Institute on Aging.

Homo erectus would be confused by current recommendations to eat 5 or 6 meals a day
Homo erectus would be confused by current recommendations to eat 5 or 6 meals a day

Calorie restriction is the only tried and true method of extending life that has worked on every species its ever been tested on.  A 1946 experiment  at the University of Chicago determined that fasting increased the lifespan of male rats by 20%.  The same effect has been demonstrated in several other studies during subsequent years.  A 2007 analysis by researchers at the University of California-Berkeley found that intermittent fasting could lower the risk of heart disease, diabetes and cancer; improve cognitive function; and guard against the effects of Parkinson’s and Alzheimer’s diseases. One study found that fasting just once per month can cut your risk of cardiovascular disease in half!

A research team at the Intermountain Heart Institute  in Utah found that during a fasted period, the body pulls LDL cholesterol from fat cells to use as energy.  This process is believed to help fight insulin resistance.

“The fat cells themselves are a major contributor to insulin resistance, which can lead to diabetes,” he said. “Because fasting may help to eliminate and break down fat cells, insulin resistance may be frustrated by fasting,” says Benjamin Horne, PhD, the lead researcher on the study. “Fasting has the potential to become an important diabetes intervention,” .

In 2011, Dr. Horne found that water fasts lead to lower glucose levels. And other studies have shown that IF increases insulin sensitivity and improves the body’s digestion of carbohydrates, making it less likely that they will be stored as fat.

Horne’s research is significant because it sheds light on the long-term benefits of IF.  Horne’s studies involved members of The Church of Jesus Christ of Latter-day Saints, Mormons and other religious cultures in Utah, who fast on a regular basis and have been doing so for decades.  As it turns out, Utah has one of the lowest cardiac death rates in the country.

Fasting is also believed to promote brain health.

“If you don’t eat for 10–16 hours, your body will go to its fat stores for energy, and fatty acids called ketones will be released into the bloodstream. This has been shown to protect memory and learning functionality, as well as slow disease processes in the brain,” says Mattson.

Intermittent fasting also raises levels of a compound called  brain-derived neurotrophic factor (BDNF), which causes stem cells in the brain to turn into new neurons.  BDNF also helps protect brain cells from the damage associated with Parkinson’s and Alzheimer’s disease.

Mattson’s research has also shown that fasting makes the brain resistant to the toxins that cause age-related cellular damage.  “Just as exercise makes muscles stronger, fasting makes the brain stronger,” says Mattson.

Many of the benefits of IF take place on a cellular level.  The end of each strand of DNA in the human body is covered by a “cap” known as a telomere.    Telomeres are responsible for protecting the chromosomes and have been likened to the plastic on the end of a shoelace.  Shorter telomeres are associated with premature death.  Fasting increases telomere length.

Recent studies have shown that fasting also re-boots the immune system.  As discussed in an article published earlier this month in the journal Cell Stem Cell,  white blood cells get broken down during a fast.  This causes changes that shift stem cells from a dormant state to one of renewal.  This research holds particular promise as a means of countering the immune system suppression caused by chemotherapy.

“While chemotherapy saves lives, it causes significant collateral damage to the immune system. The results of this study suggest that fasting may mitigate some of the harmful effects of chemotherapy,” said co-author Tanya Dorff, assistant professor of clinical medicine at the USC Norris Comprehensive Cancer Center and Hospital.

Dorff’s study also found that fasting lowered levels of IGF-1, a growth factor hormone linked to tumor progression.

While we’re still amassing conclusive data on the benefits of IF for humans, we do know that what we’ve been doing hasn’t worked.   The problem with continuous calorie restriction is that it’s not sustainable long-term and often leads to binge eating.  Short-term fasts offer a way around that.  The obesity epidemic coincided with the widespread recommendation to eat smaller, more frequent meals.  Unfortunately, this message seems to have been interpreted by many as permission to keep eating all throughout the day – in our cars, while walking down the street.  That over-consumption has come mostly in the form of refined carbohydrates and sugars, as food containing those ingredients tend to be more accessible and, often, portable.  The strategy backfired and the notion that frequent meals helps to keep metabolism elevated has been refuted.  Similarly, an analysis in the American Journal of Clinical Nutrition concluded that “cognitive performance, activity, sleep, and mood are not adversely affected in healthy humans by even as much as 48 hours of calorie deprivation.

If you’re curious about IF, you don’t need to run out and buy one of the dozens of books or documentaries on the subject.  Nor do you need to re-arrange your life. My next post will provide practical tips for implementing an effective IF protocol and avoiding common pitfalls.


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