All About Intermittent Fasting

Jennifer O'Donnell-Giles | February 19, 2018

Losing weight is the most popular New Year’s resolution, so it’s no surprise that people are constantly looking for different ways to slim down. Intermittent fasting is a relatively new technique on eating that’s touted as an effective way to lose weight, improve brain function, regulate blood sugar levels and even improve longevity. In a nutshell, it’s a schedule of eating that cycles between eating regularly and not eating at all for periods of time, otherwise known as fasting.

Intermittent fasting is not considered a diet but rather a “schedule of eating”. In fact, the only guidance regarding food is to eat whole and natural foods. There are a number of ways to go about this eating pattern such as fasting for 24 hours twice a week or simply fasting from early evening to early afternoon, combining the fast with exercise, once per month.

Short-term fasting is considered a natural human condition. Our hunter-gatherers ancestors used to do it all the time when they didn’t have enough food available, and many people still do it today for religious reasons.

Proponents of intermittent fasting claim that your body reacts to fasting at a cellular level. They explain that when we fast, fat is more readily accessible to burn, human growth hormones levels increase significantly and insulin sensitivity improves. These are all positive effects that lead to improved body composition.

There are three popular methods of intermittent fasting: the 16/8 Method, the Eat-Stop-Eat Method and the 5:2 Diet.

  • 16/8 Method: You fast for 16 hours, then eat a meal. Afterward, you fast again for 8 hours.
  • Eat-Stop-Eat: With this approach, you fast for a full 24 hours, dinner to dinner, and repeat this up to two times per week, but no more than that.
  • 5:2 Diet: This involves two non-consecutive days of eating between 500 and 600 calories with a return to regular eating for the rest of the week.

There are other ways of going about intermittent fasting, but these are the most popular methods with the 16/8 Method being the most preferred practice.

While there aren’t a lot of conclusive studies on intermittent fasting and its long term effects on the human body, one study conducted in 2014 showed a significant amount of weight loss – up to 8 percent – over a 24 week period. All body composition measurements saw positive changes, including decreases in waist circumference and visceral fat, with minimal lean muscle mass losses.

Scientists concluded, however, that it was unclear whether it was from the act of fasting or from a total decrease in calories consumed during that time period.

We should all keep in mind that intermittent fasting, like many extreme weight loss solutions, is not for everyone. Plus, it’s still unclear whether or not the results are long-lasting. When weight loss is concerned, whatever method you choose needs to be maintainable in the long run, without depriving your body of essential nutrients and physical activity, for the purpose of overall health and longevity.

Before making major lifestyle changes or embarking on a weight loss journey, be sure to consult with your primary care provider or dietitian to develop a plan that works best for you.


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Jennifer O'Donnell-Giles

Jenn Giles, R.D., C.S.S.D. is all about health and wellness. She has over 15 years’ experience, including a dual master’s degree in Nutrition and Exercise Physiology from Columbia University. She is a Registered Dietitian (RD) and a Board Certified Specialist in Sports Dietetics (CSSD). She supplements all of this with her spin instructor certification and USATriathlon Level I Coach Certification.

Jennifer is passionate about (actually, obsessed with) the sport of triathlon. She has been personally participating in triathlons since 2000 and running road races since 1992. She is a two-time Ironman finisher and has completed countless numerous marathons. She has been a member of Power Bar Team Elite since 2006 and competed as a member of the 2006 Aquaphor/Active.com Sponsored Athlete Team. She was ranked as USAT All American Honorable mention in 2006 and 2011. Jennifer does all of this along side of her husband, Patrick, who is an equally accomplished triathlete and runner. They try as hard as they can to do all of their training and racing together.

She will tell you, however, that her most important, most rewarding and most challenging job is as a mother of four. She knows first hand the challenges of maintaining optimal fitness, overall good health and achieving goals while raising a family - of which good nutrition is the cornerstone.

Most importantly, she knows how to motivate, inspire and challenge athletes based on their own abilities, strengths and everyday lifestyles. She believes there is an athlete in everyone - no matter what their abilities are – and if those abilities are manifold, then there is an even better athlete in there!

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