Month: October 2017

research intermittent fasting

There are a lot of health claims around the benefits of intermittent fasting. As there is so much to say about this topic, I had to split the research into two parts. I am sure this is nowhere near a comprehensive compilation, but I have done my best to boil down the results of a variety of research studies on the potential benefits of intermittent fasting.

One major thing to note as you read through this is that there are a lot of documented health benefits to eating less than we usually do, or in scientific terms, caloric restriction. Most studies on intermittent fasting restricted intakes to 0-50% of the participants’ calorie needs for 2-4 days per week. On the rest of the days, they could eat as much as they wanted. Some studies on intermittent reported subjects overall caloric intake, others didn’t, so it can be tough to make that distinction. In general, when animals are on an intermittent fasting regimen, they eat enough on feeding days to compensate and usually do not end up restricting calories (Anson et al 2003; Descamps et al 2005). Humans, however, usually do not eat enough to compensate and end up restricting calories via intermittent fasting (Harvie et al 2011Heilbronn et al 2005Catennaci et al 2016). In other words, the results in many of the human studies could be based on the fact that calories were restricted by fasting, not by anything special about fasting itself. We need more research to distinguish between the two!



Can intermittent fasting…

…cause fat loss?

  • Animals on both intermittent fasting and caloric restriction lose fat (Anson et al 2003; Lane, Ingram, Roth 1999Pashko & Shwartz 1996; Duan et al 2003). One study on mice showed that even though the mice on intermittent fasting averaged the same amount of calories as the normally-fed mice, they did weigh a little less (Anson et al 2003).
  • Humans lose fat with intermittent fasting too, though most humans who followed intermittent fasting ended up eating fewer calories overall, also achieving caloric restriction (Harvie et al 2011Heilbronn et al 2005Catennaci et al 2016). It is relevant to note here that in studies that asked subjects about their hunger levels, subjects were more hungry on an intermittent fasting diet.
  • In one study, women who restricted calories via intermittent fasting lost more body weight than women on daily caloric restriction (Harvie et al 2013). In both cases, their calories were restricted.
  • One study found no difference in metabolism (measured by resting metabolic rate (RMR)) between those who had intermittently fasted and those who did not (Heilbronn et al 2005).
  • Studies on caloric restriction show that subjects tend to lose muscle mass while losing fat, but can prevent this by eating a high-protein diet while restricting calories (Piatti et al 1994). Two studies have shown that while intermittent fasting, subjects lost fat and were able to maintain muscle mass while eating a lower protein diet (Bhutani et al 2010Catennaci et al 2016).
  • The boiled-down verdict: Fat loss can be achieved by eating less overall, either through eating a little bit less each day or fasting (eating ~25% of your daily needs) every other day or a couple of days per week. Based on limited research, it seems you can maintain muscle while losing fat, either by restricting calories and eating plenty of protein, or by restricting calories using intermittent fasting. It’s possible that weight loss could be faster when calories are restricted via intermittent fasting, but more research is needed to confirm that.



…preserve brain function?

  • Animals that eat intermittently experienced slower progression of age-related memory loss and  neurodegenerative diseases (Parkinson’s, Hungtington’s, and Alzheimer’s) (Anson et al 2003Halagappa et al 2007Duan et al 2003). This is also seen with caloric restriction in both animals and humans (Imai 2010;Hursting et al 2003Pitsikas et al 1990Halagappa et al 2007Yu and Mattson, 1999).
  • Mice on calorie restriction via intermittent fasting had less brain damage during and after a stroke than mice who ate all they wanted (Arumugam et al 2009).
  • The boiled-down verdict: In mice, it’s possible to prevent and slow brain aging, damage, or diseases by eating less overall, either through eating a little bit less each day or fasting every other day. We need more research to know how this applies to humans.


…help you live longer?

Check out this post to learn about the research on intermittent fasting and diabetes, cancer, asthma, and more!


Intermittent Fasting

How it Went:

I’ve still been so hungry in the mornings waiting to break my fast. This leads to crabbyness (the severity of which depends on who you ask…). Then, once I’m able to eat, I feel like I’m constantly eating to hit my macro goals. Eating when I’m not hungry leads to crabbyness. These are unfortunate happenings. During this week I missed my macros for a couple days and one morning hit a blood sugar low during my workout that forced me to realize I need more structure to get my macros in throughout the day. You can read about that here. After I created a more specific eating schedule, I was able to get my macros in a little easier, but I still felt hungry in the mornings and very full during my eating window. I haven’t really felt great at all since I started intermittent fasting.

On the flip side, my pants are definitely fitting better and I can tell that I’ve lost a bit from my waist overall. The measurements don’t reflect it this week because, unfortunately, this is the nasty week of water retention (or as my husband and I refer to it, the “natural disaster”). I expect that next week’s numbers will go back down again.



What I learned:

My fitness goal right now is primarily to gain strength and muscle and maintain cardiovascular fitness and flexibility. I’ve been using a heavy weight lifting routine (along with some moderate cardio and yoga) to achieve that goal for several months now. Lifting heavy and gaining muscle requires an increase in calorie intake to sustain muscle building and recovery, but I’ve found that I really can’t comfortably meet that goal in an intermittent fasting window. When I was eating normally, I didn’t have any trouble meeting that goal because I had more time to digest food before eating again.

I lamented about my struggles to my intermittent fasting coach friend Emily Arger, who offered to let me try her 7-Day Whittle Your Waist plan. The workouts included in her plan are designed to pair better with intermittent fasting than my heavy lifting plan, since I won’t need as many calories/macros. The main goal of the plan (as you might gather from the name), is fat loss. This is a shift from what my actual personal goals are, but I learned that heavy lifting/muscle gain is a very tricky thing to accomplish while intermittent fasting, at least for me. I started her new workout plan today, which includes 25-30-minute Tabata-style high intensity interval training (HIIT) workouts. My cat was impressed…and possibly confused.





How I did and what changed:

  Goal Week #1 Week #2
# of days 16-hour fast was achieved 7 6 7
Average daily protein intake 90 grams 85.4 grams 82.2 grams
Average daily carb intake 225 grams 209 grams 205 grams
Average daily fat intake 60 grams 73.2 grams 64 grams
Weight change   0 lbs -1.2 lbs
Body fat % change   -.5% -.5%%
Waist measurement change   -1″ +.75″
Hip measurement change   0” 0”
Thigh measurement change   -1″ +.5″


Intermittent Fasting

This week I’ve been really struggling to get my macronutrients (aka carbs, protein, and fat) in during my


8-hour eating window. I’ve just been too stuffed near the end of my window to get them in. For the past couple of days, I’ve been under my macro goals and I am really starting to feel it the next morning. Today, my workout was a struggle. I hit the worst blood sugar low I’ve had yet during my fast this morning, and it was rough.

I always like to make eating plans as flexible as I can while still hitting goals, but it’s pretty clear that trying to hit my macro goals while intermittent fasting isn’t going to happen without a bit more structure. I sat down, created an eating schedule by dividing my eating window up and scheduling meals and snacks, and dividing my macro goals amongst them. My first breakfast on this plan: egg and veggie scramble with low fat sausage and salsa, a slice of whole wheat toast, and a homemade muffin.


My macro goals for this meal: 55 grams carbohydrate, 20 grams protein, and 15 grams fat.

Actual intake from this meal: 55 grams carbohydrate (on the nose!), 25 grams protein, and 25 grams fat (I gotta work on getting this down…).

I am STUFFED. I’m used to eating a little bit less than this and spreading it out more throughout the day. At least I got in all the macros I needed to with this meal (and a little bit more). We’ll see how the next few days go with hitting macro goals. I’m hoping it will help with my hunger and low blood sugar in the mornings.


Intermittent Fasting


Today marks the completion of my first week on intermittent fasting! I’m sitting here waiting for my eating window to open, so I figured I might as well hammer out a blog post. If you’re not sure what I’m talking about, go here to read about my intermittent fasting experiment. Here’s a quick rundown on my week:

How it went:

It’s been a little rough, to be honest. I’m starving in the mornings waiting to eat, pretty much no matter what I’ve eaten the night before. My hunger was a little better when I hit my macros perfectly (or darn close) the day before. At the beginning of a day, it feels impossible to be satisfied once I start eating, then I find myself stuffed with only two hours left to go in my eating window. Then I’m feeling like I should eat because my window is about to close and I know I’ll be starving in the morning if I don’t eat. As I am generally a promoter of intuitive eating (creating an eating schedule based around your body’s own natural hunger cues), this is totally backwards to me. I’m not eating when I am hungry, and I’m eating when I’m not hungry. Not to mention the fact that when I’m starving, I’m much less likely to choose healthy options. For me, my desire for Cajun tots and nachos with cheap, plasticky cheese is directly proportional to the length of time I’ve been hungry. Thus, I struggled to stay within my fat goal. Hunger cues are adaptable, so I’m curious to see if these issues improve in the next two weeks.

I haven’t been hungry most evenings, even though I stop eating at 6 pm and don’t go to bed until around 10 pm. That’s not too much of a surprise, since I’m typically hungry every 4 hours or so normally.



One pleasant surprise: working out while fasted has not been that tough. I like to work out in the mornings and did not want to change that schedule even though I was fasting, but I was worried. I get low blood sugar, especially when exercising, so I was really concerned about completing my normal workouts while fasted. Turns out, working out actually distracted me a bit from my hunger. I did schedule my workouts to end right at 10 am as my eating window opened, because I’m always extra hungry right after my workout. That part has been going great!

What I’ve learned:

Intermittent fasting is probably a great option for a certain type of person – an intermittent fasting “candidate,” if you will. This person is probably not used to eating breakfast or can easily skip breakfast without too much notice, likes to eat larger meals, doesn’t have issues with high or low blood sugar, and has irregular or non-existent hunger cues.



On top of that, a good fasting candidate has a schedule that can work with their fasting instead of against it. Because I work from home, I am mostly able to eat when my window opens, but I have thought about the fact that if I were working my former full-time job, it would be very difficult to follow intermittent fasting. I can’t imagine waiting any longer to eat than 10 am, and 10 am would not be a realistic time to eat at my desk job.

It’s also possible that this person has a sedentary lifestyle so they do not need to eat often to meet their energy needs. I often teach about matching energy needs with energy intake throughout the day, which is tough to do if you’re active for 12 hours but only able to eat for 8.

If these characteristics describe you, you may be a great candidate for intermittent fasting.

How I did and what changed:



  Goal Week #1 Week #2 Week #3
# of days 16-hour fast was achieved 7 6    
Average daily protein intake 90 grams 85.4 grams    
Average daily carb intake 225 grams 209 grams    
Average daily fat intake 60 grams 73.2 grams    
Weight change   0 lbs    
Body fat % change   -.5%    
Waist measurement change   -1″    
Hip measurement change   0”    
Thigh measurement change   -1″    


Even though my weight stayed the same, I did lose an inch from my waist and another from my thighs during this week. One of the claims of intermittent fasting is that it will promote fat loss, particularly in the abdominal area. My scant week on the diet shows that could be the case! Keep checking in for more updates on what the research says about intermittent fasting.


Intermittent Fasting

Emily Arger, Certified FASTer Way to Fat Loss Coach

For some, intermittent fasting can mean a significant lifestyle change that can have challenges to implement. I myself have struggled a bit with hunger and fullness at inconvenient times throughout my few days on intermittent fasting. I chatted for a few minutes with Emily Arger, Certified FASTer Way to Fat Loss Coach and creator of the 7-day Whittle Your Waist Mini-Course. Emily coaches women on following an intermittent fasting lifestyle and also provides 25-30 minute home workout plans to these ladies. Check out her answers to some of my questions about intermittent fasting:

How did you first learn about intermittent fasting?

I actually heard about it before I had my kids – I read a book called Eat, Stop, Eat by Brad Pilon about the benefits of fasting. It’s a great book, but it was actually a bit different from what I teach now. I read it and it was intriguing, it was different. At first it was never something I intended to coach. I thought people might think I was crazy, because we are so ingrained with the idea that we need to eat 5-6 meals per day. It wasn’t until much later that I actually picked it back up again, after my kids were a little bit older.



What made you want to teach intermittent fasting?

I had done a lot of measuring and using containers to portion foods and I was so over that. I kept asking myself if that was a lifestyle that I wanted my clients to live forever, and the answer was no. When you master the intricacies of intermittent fasting – making sure you get in your macros and eat enough – and once you adapt to [intermittent fasting], there is so much freedom in it. That’s why I wanted to start sharing that with the ladies I work with.

What is your favorite thing about intermittent fasting?

Honestly, the ease. The ease and freedom of it. The ladies who go through the first few days of Whittle Your Waist start off thinking that they can’t do it, but once they adapt to it, they love the freedom of it. They say, “Hey, I’m not that hungry and I’m not spending my entire day thinking about food anymore.”

What do you see as the biggest challenge of intermittent fasting?

I think it’s definitely making sure you’re getting enough. I know that sounds crazy, but once you get used to it, it can be tempting to get to 10 am or noon and say, “Hey, I’m not hungry yet” and they try to push that window a little bit farther, but when they start so much later, it’s a big challenge to get say, 1800 calories in in only 6 hours. It’s important to plan things out, especially at the beginning, and get a coach if you’re struggling to meet all your macronutrient and micronutrient needs in such a small window.



What’s your #1 piece of advice to someone wanting to try intermittent fasting?

I would say to seek out the scientific-based research on it, because we’ve been inundated with these myths like “you have to eat every 2-3 hours” or “breakfast is the most important meal of the day.” It’s important to read the research yourself to understand the benefits of intermittent fasting and how it’s good for you. Otherwise, you’re going to read a magazine or something that tries to tell you that what you’re wanting to do isn’t right and it gets confusing. It’s important to ground yourself in the research so you can really understand why intermittent fasting works and what it does for your body.

Intermittent Fasting

Yesterday was my first day following an intermittent fasting lifestyle. I’m using a 16:8 protocol – if you want to know more about that, you can read my last post here. I chose to make my eating window from 10 am to 6 pm. Read on to see how the first day went!

6:30 am Woke up. Usually this is when I get my breakfast ready, but not today! Got my boys sent off to school.

7:00 am Made and drank some green tea. Since I’m a big breakfast eater I was a little concerned that waiting until 10 am would be a struggle. I made genmaicha green tea because it’s made with toasted rice and has a bit of a savory flavor – I thought maybe it would help trick me into thinking it’s a little more substantial. Then I got to wondering: genmaicha has actual bits of toasted rice steeped in it…does it have calories or carbohydrates?? Had to look it up. Good news – it has neither! Genmaicha is good to go during my fasting window.

7:30 am Had my first teeny desire to eat. Drank more tea.

8:00 am This is my normal workout time. I decided to postpone it half an hour so that I could eat right after my workout. In the past I haven’t done well working out on an empty stomach. We’ll see…

8:30 am Workout time. Tummy is growling big time…I’m 32 oz. of tea in. This not eating has been great for my hydration!

10 am Food! Finally! Toast with avocado, poached egg, curry, and garlic.


10:30 am Still feeling hungry – I went ahead and made my typical post-workout protein smoothie and drank it. Still not totally satisfied.

11:45 am Ate lunch – leftover salmon, stuffing, and salad. Still not satisfied…this is getting old already. I need to work on adjusting my portions to fit a smaller eating window.

2:30 pm Feeling hungry, ate a yogurt.

4 pm Realized I have to start dinner soon if I’m going to get it ready, take my son to practice, and eat before 6 pm. That will take some getting used to!

5:30 pm Ate dinner – whole wheat pasta, chicken breast, and roasted vegetable sauce. I got a little panicky about the thought of not eating until 10 tomorrow so I overdid it a bit…I had two bowls of pasta then chased them with some apples and caramel sauce. I ended up hitting my protein goal for the day but being a bit behind on calories (200 calories), carbohydrates (20 g), and fat (12 g). I felt stuffed.

7:30 pm I’m still stuffed, but it’s nice to be all done with worrying about cooking, cleaning, and snacking so early in the night.



Intermittent Fasting

intermittent fasting


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
  • Longevity
  • 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!


Intermittent Fasting