The Truth About Meal Frequency: Is Intermittent Fasting for You?
Written on March 26, 2012 at 7:46 am, by Eric Cressey
Today’s guest nutrition blog comes from former Cressey Performance intern Tyler Simmons.
“It’s best to eat 5 – 7 times a day.”
“Eating every three hours fuels your metabolism.”
“If you skip meals, your body goes into ‘starvation mode,’ you gain fat, and burn muscle for energy.”
Chances are that you’ve probably heard something like the above statements if you’ve read anything about diet or exercise in the last ten years. Many of you (myself included) probably spent a lot of time preparing and eating meals, in the hopes of optimizing fat loss and better muscle gain.
What does the data really show about spacing out your meals? When I started researching the topic of meal frequency in 2010, I assumed there was ample scientific evidence to back up these nearly unanimous claims that smaller, more frequent meals were better than larger, less frequent meals. Boy, was I disappointed.
To my surprise, the scientific literature had some different things to say. My research focused on how changing meal frequency impacts two different things: 1) Metabolic Rate and 2) Weight Loss. What I found was compelling evidence that reduced meal frequency, sometimes known as Intermittent Fasting (IF), could actually help me, so I started an experiment.
In the summer of 2010 I was living in Alaska doing construction and labor, as well as doing off-season training for Track and Field (sprinting, jumping, and lifting). For years I had focused on eating every 2-3 hours, but based on my new findings, I decided to limit all omy food intake to an 8-hour window, leaving 16 hours of the day as my fasting portion.
Despite doing fasted, hard labor all day, then lifting, sprinting, and playing basketball, I managed to set records on all my lifts at the end of the summer. Not only was I stronger than ever, but I got leaner too.
Here’s pictures from before and after, about 2 months apart:
 
Getting lean wasn’t even my main goal; the idea that I could be free from eating every three hours without suffering negative side effects was extremely liberating. No longer was I controlled by arbitrary meal times and tupperware meals in a lunch box. During this summer, I developed the ability to go long periods of time (18-24 hours) without food, and not get tired, cranky, our mentally slow down.
So why didn’t I catabolize my muscles, drop my metabolic rate, and end up looking like skinny-fat Richard Simmons (no relation)?
The Science
The idea that eating several smaller meals is better came from a few pieces of information. The first was because of an association between greater meal frequency and reduced body weight in a couple of epidemiological studies, although this only shows a correlation, not causation. Breakfast eaters are more likely to engage in other health activities, such as exercise, which explains the relationship. In the most comprehensive review of relevant studies, the authors state that any epidemiological evidence for increased meal-frequency is extremely weak and “almost certainly represents an artefact” (1).
The second piece is related to the Thermic Effect of Food (TEF), which is the amount of energy needed to digest and process the food you eat. Fortunately, this is dependent on total quantity of food, not on how it’s spaced, making the distinction irrelevant.
So, now we can see that the supposed benefits from increased meal frequency do not hold up to closer inspection, but why would we want to purposefully wait longer in between meals?
Originally, researchers thought Caloric Restriction (CR) was the bee’s knees. Preliminary research showed that CR slows aging, reduces oxidative damage, and reduces insulin and levels. All good, right? Unfortunately, these benefits come with some nasty trade-offs, including reduced metabolic rate, low energy levels, constant hunger, and low libido, pretty much what you would expect from chronically restricting food intake. These were not happy animals.
Recent research has shown that Intermittent Fasting or reduced meal frequency can convey many of the benefits of CR while avoiding the negative side effects. Some of these benefits include:
- Favorable changes to blood lipids
- Reduced blood pressure
- Decreased markers of inflammation
- Reduction in oxidative stress
- Increased Growth Hormone release
- Greater thermogenesis/elevated metabolic rate
- Improved fat burning
- Improved appetite control
Some of these effects may be secondary to the reduction of calories due to improved appetite control, or they may be primary effects of IF, the research is not conclusive on this yet.
One of the most interesting findings was that contrary to conventional wisdom, reduced meal frequency actually causes an increase in thermogenesis (metabolic rate), which is mediated through the increase of catecholamines (stress hormones), such as adrenaline and norepinephrine (1,2). Yep, you read that right: instead of slowing your metabolism down, it speeds it up. Catecholamines also help with the liberation of fatty acids from fat cells, making them available to be burned as energy.
That’s the “why” and the “how” for some of the effects of IF. Whatever the mechanism for it, IF seems to be effective for at least some people, myself included. But before you rush off to go start fasting 16 hours a day, here are some tips and caveats.
Important Considerations
Many people ask me if IF is good or bad, but as with most things, it depends. IF is not appropriate in certain situations. It can be good or bad, depending on who you are (your current health status/lifestyle) and what your goals are. IF is a stressor on the body; one of the primary effects is an increase in stress hormones. If you’re lacking sleep, eating low quality foods, stressed out about your job, and excessively exercising then don’t start an IF protocol. It will backfire and you will end up fat and tired!
Only experiment with an IF program if you are getting 8-9 hours of sleep a night, eating a high quality diet, appropriately recovering from exercise, and don’t have too many mental/emotional stressors.
As far as what goals this works for, common sense applies here. IF is generally best for people who are already moderately lean and are trying to get leaner. If you’re trying to put on 30 pounds of mass, don’t start IF. If you’re an athlete with a very heavy training load, don’t try IF.
For those of you who fit the criteria of goals and health status, I suggest experimenting with the 8-hour fed/16-hour fasted periods. Eat quality foods to satiation in your eating window, especially focusing on the post-training period.
Keep in mind that IF is not for everyone, but it can be a powerful tool at certain times. Most importantly, even if IF isn’t for you, remember that you shouldn’t stress out if you miss a meal occasionally!
Additional Note/Addendum
Many readers have noted that this is similar to what Martin Berkhan does in his LeanGeans protocol. Martin Berkhan was certainly influential in the thought process behind this, and I don’t mean to take anything away from him. To be clear, LeanGains is much more complex than a 16:8 fasting:eating period. LeanGains involves calculating calorie intake, fluctuating calorie intake +20% on training day/ -20% on off days, macronutrient cycling (high carb/low carb), supplementing with BCAA’s, etc. I didn’t use any of these techniques during my ten week experiment, I just ate to satiety during an 8-hour window. Martin is a great resource for people that want to learn more, especially on the body composition side of things. His website is leangains.com.
About the Author
Tyler Simmons is the owner and head Nutrition/Strength & Conditioning Coach at Evolutionary Health Systems. He has his bachelors in Kinesiology with a focus in Exercise Science and Exercise Nutrition from Humboldt State University. A former collegiate athlete, Tyler specializes in designing training and nutrition programs for athletes of all levels, as well as general population. Learn more at EvolutionaryHealthSystems.com.
Related Posts
Why You Should Never Take Nutrition Advice from Your Government
Anabolic Cooking: Why You Don’t Have to Gag to Eat Healthy
References
1. Bellisle, F., & McDevitt, R. (1997). Meal frequency and energy balance. British Journal of Nutrition, 77, 57-70.
2. Mansell, P., & Fellows, I. (1990). Enhanced thermogenic response to epinephrine after 48-h starvation in humans. The American Journal of Physiology, 258, 87-93.
3. Staten, M., Matthews, D., & Cryer, P. (1987). Physiological increments in epinephrine stimulate metabolic rate in humans. American Journal of Physiology, Endocrinology, and Metabolism, 253, 322-330.
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March 28th, 2012 at 5:02 pm
Although I appreciate the “considerations” section, I had to laugh when I read them. Let me get this straight, if you are pretty lean, not trying to add muscle mass, get 8-9 hours of good sleep each night, aren’t terribly stressed, etc., this plan might work for you. In other words, if you are a professional or wannabe bodybuilder without kids and don’t have to work much outside of your bodybuilding, you might want to try this. Why, then, the title “The Truth About Meal Frequency”? If there is any “truth” to your argument, it is so nuanced that most people wouldn’t want to even consider IF. It would be helpful, then, if you made clear from the start that IF is not going to work for most people trying to lose weight. Part of the problem with helping my clients lose weight is that the read fitness mags, blogs, etc. that have so much hard to decipher, often contradictory information that they either try the wrong things or they don’t know who and what to trust. Smaller, more frequent meals makes a lot of sense, at the very least from a behavioral perspective (if not from a physiological one, and I’m not convinced by the arguments here that the science is fully understood), so let’s not muddy the waters by planting the idea that such an extreme plan as IF is useful for anyone except a very few individuals.
March 28th, 2012 at 5:12 pm
The other point is, obviously, that total number of calories taken in during a day is still the basic issue with weight loss. Of course, this is contrasted with calories burned. Sure, metabolism is a factor, and metabolism can vary some depending on several factors. I think the main problem with IF is discipline–whether or not you can actually stick to a program. As the article and most of the discussion seems to point out is that certain people, mostly young, might be able to pull this off, but MOST will struggle with it. Let’s call IF what it is…an extreme weight loss method that is loaded with pitfalls. That it works for some people does not mean it is a good idea. Heck, Atkins works for some people.
March 28th, 2012 at 7:17 pm
Carl, I appreciate the feedback and your thoughts.
I believe that you missed the main takeaway point from this article – that there is no scientific basis for the idea that eating several small meals per day is an inherently better way to eat, and that stressing about missing a meal is totally counterproductive.
I tested the idea that small and frequent feedings are better by doing the polar opposite, and seeing what happened. I had good results from it.
The idea that I’m trying to promote here is that meal frequency is a matter of personal preference- use what works for you (high frequency, low frequency, or IF), don’t be bound by an idea that isn’t supported by any real evidence.
March 29th, 2012 at 12:30 pm
This all makes me think that once you reach a certain level of “perfection” in your diet, you’ve got to periodize your diet in a way to reach new levels of leanness etc. Just a thought.
Tyler, would you say that eating at regular intervals should be a stable and IF used in addition? Or is there enough evidence to say that people should shift to eating this way?
If this is going to be used in addition, do you have any resources that provide safe and effective options (like 8/16 2x a week for 6 weeks?).. Just curious. Thanks for the article and keep it up at CP.
March 29th, 2012 at 3:01 pm
Kristen, thanks for the compliments on the article.
How I think about diet is kind of in a hierarchy of nutrition variables – the most important thing is food quality. Once you’ve got food quality to a reasonable level, you can move in to more advanced strategies like manipulating macronutrient ratios, and nutrient timing. So yes, I would agree with you.
As for your second question, it just depends on who you are and what your goals are. Some people IF every day, year round. Some people use it as a tool for occasional use. The main takeaway I want you to have from this is that meal frequency should be based upon personal preference – experiment and see what works best for you.
Good resources are John Berardi’s free IF ebook, Brad Pilon’s eat-stop-eat, and Martin Berkhan’s leangains.
March 29th, 2012 at 8:35 pm
I used intermittent fasting last summer and lost 34 lbs in 3 months so it is good for me. I find that it’s much easier to cut my calories this way rather then taking away foods that I like. I also found that those 6 meal a day diets actually make me want to eat more and I get headaches if I don’t eat every 3 hours when on them. IF is just so much easier for my lifestyle.
April 3rd, 2012 at 11:41 pm
Thank you for the response and recommendations! About to
Check em out…
April 14th, 2012 at 2:39 pm
I came across the leangains system last weekend, and on day 6 of IF. I’m actually following your method more, as I don’t exercise and all his macronutient talk and stuff like that is well beyond me.
Would like to add a tip for the girls: I started it while on my cycle since hormones are all out of whack anyways, and it was actually way easier for me. I also started calorie counting the same day, and have lost 7 pounds. The leangains system also lets us eat for 10 hours rather than 8. ^_^
My question, Tyler, is how appropriate do you think IF is for people who don’t do any exercise? Reducing my meal frequency to just lunch, snack, and dinner has made calorie-restriction much easier than trying to each small meals 5-6 times a day (small meals make me hungry), but all the information I’ve seen regarding IF seems geared for body-builders and people aiming at single-digit body fat percentages. I was at 205 last week and trying to get down to 160 lbs.
June 25th, 2012 at 3:40 pm
I have had success with IF but don’t try to do an organized IF schedule. I have done the 8 hour window and had success with it but now I just use IF more as a convenience tool. Don’t have time for lunch no biggie. Running late for work and don’t have time for breakfast no big deal. I have found this in and of itself very liberating.
January 24th, 2013 at 10:48 pm
This is just flat out bogus. I’m pretty sure anyone doing physical labor for work that’s already lean won’t gain regardless of their eating habits not to mention you look like you’re about 20 and probably don’t gain anyways!
February 24th, 2013 at 9:38 am
K obviously has no personal experience with IF! It doesn’t matter what age you are, the research proves that IF is the better way to go if you are trying to preserve (or GAIN) lean muscle mass while also losing fat. If you’re just looking for a way to get skinny, then IF is not for you and you should go blow your money on some diet pills.
My husband and I are much older than 20 and we have seen it work extremely well for both of us. And that is while my husband is training for a marathon and triathlons and while I am doing intense kettlebell training that would put most men to shame. Our workouts have actually IMPROVED since starting IF!
I think the most liberating part about IF is that for a small woman like me (who has lost 70 pounds and KEPT it off), we don’t get to eat a lot of calories in a day so having to obsess over every single thing I ate was really annoying. Now that we IF, we still focus on eating an extremely clean and organic diet but I don’t have to nit-pick as much about my portions. It’s so freeing!
June 10th, 2013 at 8:03 pm
This is the stuff that is wrong with the fitness industry and the image obsessed fitness nuts it produces. Look at the author’s before and after pictures. It’s comical the change! He’s ripped in one and well ripped in the other. How screwed is our society that a (child) person with a degree in kinesiology can report “findings” from a self study that show an obsession with appearance. It is one thing to desire a “lean” physique or to attain a healthy weight. It is another to obsess until the veins ripple around your hip pointers. I expect articles like this on Bodybuilding.com but not on Cressey’s site.
July 5th, 2013 at 8:34 pm
Tried the 16 hr fasting for a few months and went from 10% bf to 8. all seemed good until i noticed that my bench press had gone from 400lbs to 360.
October 20th, 2013 at 5:39 pm
I suggest you read up on diffren options no matter who you are I lost 82 pounds at home doing home work outs and changing up my diet al the time, I’m now doing IF and I don’t find t to be extrem at all and I weigh 188lbs I find it a lot easier and I’m a HCA. So my job is laborious and I also weight lift and do HIIT, it is best to work out on IF in your fasted state this can be in the am or pm 2-3 hours after a meal and it can differ for people so if you find you don’t have the energy in the morning do it later 🙂
March 14th, 2016 at 1:16 am
the 24 hour once or two times per week does not increase your stress levels?