Intermittent fasting is a big time buzz-phrase these days. I see people posting about it on Facebook and Instagram, some of my fitness-savvy friends advocate for it, and I read an article about it in Women’s Health magazine. I’ve seen a teensy bit of research floating around but I’m ready to dig in and really see what it’s all about and whether or not it’s something I might incorporate into my practice.
Today I started my own intermittent fasting experiment. I will be trialing an intermittent fasting lifestyle for the next 3 weeks to practice it, research it, and teach you about it! Along the way, you’ll get all the details of how I’m feeling, whether or not my weight, measurements, blood pressure, or heart rate change, and how cranky I am (I’ll let my husband score that one – for objectivity’s sake). For today, let’s go over some basics of intermittent fasting:
What is intermittent fasting?
Boiled down, intermittent fasting basically means alternating between eating normally and restricting your food intake on a regular schedule. This manifests in many different styles. Some of the more popular protocols are detailed here:
- 16:8 or 20:4 – This is a daily goal to limit time spent eating during the day, making the nighttime fast longer. In a 16:8 schedule, people fast for 16 hours each day and limit their eating to an 8-hour window each day. This is the protocol I will be using. In a 20:4 schedule, people fast for 20 hours per day and limit the eating window to 4 hours.
- Alternate-day Fasting – I’ve read about a few different schedules under this name, but the most common is a 5:2 schedule. In a 5:2, you would eat normally 5 days of the week, and 2 days during the week (you can split them up) you fast entirely or restrict intakes to 500 calories per day.
- Extended Fasting – In extended fasting, folks avoid eating or restrict the types of foods they eat for longer periods of time, anywhere from 2 days to several weeks or months.
Can you eat anything during the fasting period?
That depends on the type of protocol you’re following, but best I can tell, most protocols recommend only calorie-free beverages like black coffee, tea, or water during the fasting period. Anything with calories breaks the fast.
Are there limits to what you can eat during your eating window?
Generally, no. Most websites and researchers recommend eating healthful foods, of course, but there are not too many limits. Some protocols advocate for tracking what you eat to make sure that you meet your macronutrient (carbohydrate, protein, and fat) needs during the eating window. Other plans allow intermittent fasters to eat however much they choose. The end goal is to eat as much food as you need, just in a shorter period of time.
What are the benefits of intermittent fasting?
There have been many claims about the purported benefits of intermittent fasting. I’m working through the research on a bunch of them and I will let you know what I find out in a future post (edit: here’s a link to my post on research)! In what I’ve read so far, supporters of intermittent fasting report improvements in:
- Focus, productivity, and mental performance
- Stress resistance
- Resistance to chronic diseases like diabetes, cancers, and Alzheimer’s
- Fat loss, especially belly fat, while maintaining muscle mass
- Inflammation levels
- Blood pressure and heart rate
How does it do all that?
Honestly, I have a bit more research to do in this area but I will keep you up to date as I learn more. In the initial articles I’ve read, the authors credit ketosis as the cause of many of the benefits listed above. When humans fast for or avoid carbohydrates for a prolonged period of time, they basically run out of glucose energy from food, so the liver starts producing ketones to use as an alternative energy source. It’s sort of like a tank of gas on a hybrid car – if the battery runs out, you can run on gasoline instead. What I need to learn now is why supporters of intermittent fasting believe these ketones are so beneficial. I have some reading to do!
What changes will you be making?
I’m starting out by using a 16:8 protocol and setting my eating window from 10 am to 6 pm. There will likely be a little trial-and-error involved, I imagine. I’m keeping my workouts the same (30 mins cardio, heavy weight lifting, and 30 mins yoga 5 days per week) and eating the same types of food I usually do. I expect that I may have to play with my workout schedule a little bit since I haven’t done well with working out on an empty stomach in the past. Tune in tomorrow to see how I did on my first day!