Intermittent Fasting: What’s the Buzz About?
I’m throwing you all for a loop here. Last month I spoke about a quick and healthful breakfast on the blog. I’m all about sharing both sides of a story, so I thought, why not speak about intermittent fasting? This is definitely a hot topic, so be sure to continue reading to learn about:
What is intermittent fasting
Types of intermittent fasting
Potential benefits of intermittent fasting
Research on intermittent fasting
Who should use caution with intermittent fasting
What I’ve seen throughout the years
Feel free to jump to specific parts of this blog post if desired!
What is Intermittent Fasting?
Fasting: “Abstinence from food or drink or both for health, ritualistic, religious, or ethical purposes.” -Britannica Dictionary
Intermittent fasting could be summarized into the following:
Complete or partial restriction in energy intake on 1-3 days per week.
Complete restriction in energy intake for a defined period during the day that extends the overnight fast.
It is important to know that fasting is different from a calorie restriction. In a calorie restriction, daily intake is reduced, however meal frequency is usually maintained.
Types of Intermittent Fasting
When fasting is spoken about, many people will think of “time restricted feeding.” This is where food is consumed within a specific timeframe (example: 12 PM – 6 PM). Time restricted feeding is the main type of intermittent fasting this blog post will speak on, however, there are other types of intermittent fasting. They include:
Alternate-Day fasting (this is where individuals alternate fasting days with days that they eat)
Modified fasting (this is where individuals will consume 20-25% of their energy needs on fasting days and eat regularly the other days)
Religious fasting
Ramadan fasting
What’s the Buzz all About? What are the Benefits Associated with Intermittent Fasting?
Intermittent fasting has been talked about numerous times over the past several years. It has been said to help individuals:
Lose weight
Improve glucose and insulin levels
Improve insulin resistance
Decrease hyperlipidemia
Decrease inflammation
Fat burning typically begins after ~12 hours of fasting and is escalated between 16-24 hours of fasting.
Image from: 7 Sigma Physiques
Intermittent fasting has also been said to promote a sense of “detox” within the body. This is because it:
Produces autophagy
Increases glutathione
You’re probably thinking, okay, what the heck are those two words?! Well, autophagy is the body’s way of cleaning out damaged cells, in order to regenerate newer, healthier cells. It is said that food restriction increases autophagy. Glutathione is an antioxidant. It is said that intermittent fasting can increase this antioxidant.
There is research that indicates intermittent fasting can also be beneficial for brain health. Without going into too much detail, it can improve neural connections, while protecting neurons against the accumulation of amyloid plaque (this is a protein that is prevalent in people with Alzheimer’s disease). There is potential that people who are predisposed to Alzheimer’s disease could decrease their incidence by engaging in intermittent fasting.
What Does the Research Say on Time Restricted Feeding
Although there are several forms of intermittent fasting, time restricted feeding is the most popular. The key point with time restricted feeding is that calorie intake is generally not controlled, but the feeding times are. What’s involved with time restricted feeding:
Consume as much energy intake within a defined window of time
Usually from 3-12 hours
Fasting window lasts from 12-21 hours
Time Restricted Feeding with Obese Men with Prediabetes Research Study
There was a research study from the University of Alabama that enrolled obese men with prediabetes. There were two groups:
Meals from 7 AM – 3 PM
Meals from 7 AM – 7 PM
See the results in the infographic to the right
Of note: Most studies that focus on intermittent fasting and human health have less than 50 participants, with fairly short intervention periods. However, the studies that have been conducted have shown to help with cognitive decline, early stage cancers, metabolic syndrome, type 2 diabetes, prediabetes and obesity. Also, most health benefits in humans are often hypothesized from animal studies.
Time Restricted Feeding and Resistance Training Research Study
Another research study looked at the effects of time restricted feeding on 34 resistance trained males. This study was conducted by Moro et al and is the only study reporting effects of skeletal muscle growth with resistance training and fasting. It included the following:
Males were assigned to time-restricted feeding (TRF) or normal diet (ND)
Study was 8 weeks in duration
100% of energy needs were consumed for both groups through meal consumption
Meals were matched for calories and macronutrient distribution
TRF: Meals at 1 PM, 4 PM and 8 PM
ND: Meals at 8 AM, 1 PM and 8 PM
No snacks
Except 20 grams of whey protein could be consumed 30 minutes after each training session
Study population
Males were around 30 years old
Each week participants were contacted by a RD in order to check adherence to diet protocol
Participants needed at least 5 years of continuous resistance training experience prior to the study
Training
3 weekly sessions on non-consecutive days
Heavy lifting
Exercised between 4-6 PM
To the left you can see some of the results of this study. The main takeaway points are:
Intermittent fasting can be used for strength athletes without negatively affecting strength and muscle mass
Intermittent fasting can improve health related biomarkers, decrease fat mass and at least maintain muscle mass
Note: Remember, the calories and macronutrient distribution were the same between groups. It was only the timing that was different. Exercise was also in the late afternoon, after both groups had ate breakfast and lunch and were still going to eat dinner.
Who Should Use Caution with Intermittent Fasting
Individuals could try intermittent fasting and determine if it is right for them. However, there are a handful of people that would not benefit, or would need to take extreme caution, from partaking in intermittent fasting. Those include the following individuals:
Type 1 diabetes
On medications for diabetes
Pregnant or breastfeeding
History of an eating disorder
Medically unstable
Examples include heart failure, chronic kidney disease
Cognitive decline without adequate support
Underweight
Pediatric population
Cancer diagnosis
What I’ve Seen Throughout the Years
Like I said before, I like to show all sides of the story. This is why I spoke about breakfast in my previous blog post and intermittent fasting for this one. After you gather all the information, it is ultimately up to you to determine what habits you want to instill in your life. That being said, here are some things I have noticed:
Calorie restriction in general will lead to weight loss. Intermittent fasting tends to restrict calories because there is only so much time in the day for food consumption.
It is usually in the evening when winding down for the night that less nutrient dense food options are consumed (examples: alcohol, desserts, snacks when in front of the TV). Intermittent fasting usually takes these foods out because eating should be ceased prior to this time in the evening.
When we instill a healthy habit, we tend to instill other healthy habits in our lives. For example, if someone does intermittent fasting, it is likely they are eating more nutrient dense foods instead of many processed foods.
Breakfast consumption has led to decreased cravings, and thus decreased over indulgence in the evening.
When someone is intermittent fasting and strength training and do not eat prior to their workout, they are unable to work as hard and fatigue more easily.
Intermittent fasting: Is it for you? If you have practiced intermittent fasting, we would love to know your experience in the comments!
References
“A Primer on Fasting.” Cleveland Clinic.
“An Intro to Fasting.” Dr. Mark Hyman, 16 Apr. 2019, https://drhyman.com/blog/2019/04/16/an-intro-to-fasting/.
“Are There Any Proven Benefits to Fasting?” Johns Hopkins Health Review, https://www.johnshopkinshealthreview.com/issues/spring-summer-2016/articles/are-there-any-proven-benefits-to-fasting.
Collier, R. “Intermittent Fasting: the Science of Going Without.” Canadian Medical Association Journal, vol. 185, no. 9, Aug. 2013, doi:10.1503/cmaj.109-4451.
Feldscher, Karen. “Intermittent Fasting May Be Center of Increasing Lifespan.” Harvard Gazette, Harvard Gazette, 29 Nov. 2018, https://news.harvard.edu/gazette/story/2017/11/intermittent-fasting-may-be-center-of-increasing-lifespan/?utm_source=twitter&utm_medium=social&utm_campaign=hu-twitter-general.
Gleeson, Jane Racey. “Intermittent Fasting: Is It Right for You?” Health & Wellness Topics, Health Tips & Disease Prevention, https://healthblog.uofmhealth.org/wellness-prevention/intermittent-fasting-it-right-for-you.
Moro, T., Tinsley, G., Bianco, A., Marcolin, G., Pacelli, Q. F., Battaglia, Gentil, P., Neri, M., Paoli, A. (2016). Effects of eight weeks of time-restricted feeding (16/8) on basal metabolism, maximal strength, body composition, inflammation, and cardiovascular risk factors in resistance-trained males. Journal of Translational