July 30, 2014

Will Restricting Carbs Make You a "Fat-Burning Beast?"

photo: pixabay

By Tiffany Reiss; With a Long-Winded Intro by Crabby McSlacker

So for years I've been intrigued by notion of "Fat Adaptation," a concept advanced by Mark's Daily Apple and others. The idea is that by strategically restricting carbohydrates, you can reprogram your body to use fat as fuel instead of glycogen.

According to Mark:

If you’re fat adapted, the genes associated with lipid metabolism will be upregulated in your skeletal muscles. You will essentially reprogram your body. 
With that comes great benefits!  Like more energy available during exercise and throughout the day, and an easier time burning fat and losing weight than if you are a "sugar burner."

However, most mainstream nutritional advice says almost the opposite: Watch the fat, eat more carbs. These experts claim you need a crapload of carbs for optimal nutrition, especially if you are doing something athletic.  

And yeah, everyone agrees you need protein and that you should avoid refined and processed foods as much as possible and you should be eating plenty of produce.  But as to what else you should be fueling with, the "Are Carbs Good or Are They Bad" debate rages on.

I got so tired of hearing the contradictions that I asked Tiffany Reiss what she thought.  As regulars may recall, Tiffany is a smarty-pants professor type who knows a lot about exercise physiology. (Her bio is below).

So, is her answer simple and straightforward?

Hell no! Because it turns out it's a complicated question!

So those of you who like to geek out, here's Tiffany take on the whole "Should I restrict Carbs" question.

--Crabby

To Carb or Not to Carb

It’s such a simple question: Are carbs good or are they bad? Should we eat them or shouldn’t we?




The answer is: Yes….and No. It depends. So what does it depend on? Genetics, muscle fiber type, activity level, activity type, gut microbes and age to name a few. For now I will just focus on the genetics of it all.


Genetics/Epigenetics

You are your genes, and your environment impacts your genes. We all have a genetic construct and everyone’s is slightly different.



But we now know that our environment influences our genes by turning some genes on and some genes off. It turns out both nature and nurture play roles in who we are and what we ultimately become.

What’s important is which genes are turned on and active, and that can be influenced by our environment. What constitutes our environment? Diet, activity, stress, smoking, exposure to chemicals, toxins, etc… Pretty much how and where you live your life. These are actually new fields of study called: Epigenetics and Nutragenomics. How our environment influences our genes (Epigenetics) and how what we consume influences our genes (Nutragenomics).

Now why is this important? Our bodies adapt. They are amazing machines that adapt pretty well to the myriad of environmental stimuli to which we expose them, if we have the genes that can adapt or turn on/off based on the environmental stimuli. Below is a good example of an adaptation:

Muscle Fiber Type/Activity Level/Activity Type


Your muscle fiber type is genetic. There are 2 basic types of muscle fiber tissue:


  • Type I: endurance oriented and aerobic (long distance running, swimming, biking, yoga, etc….)
  • Type II: strength/power oriented and anaerobic (resistance training, football, sprints, baseball, etc….)

You get the picture. Type 1 tissue dominates during long duration, lower intensity activity; Type II during short duration, high intensity activities.

Most people are a good combination of Type I and Type II and there are varying levels of isoforms that actually give us a broad spectrum or range of that muscle tissue based on the way we train or exercise. They may vary a bit one way or the other, say 55% Type I and 45% Type II, but the average individual is a good mixture.

Tiffany may not ever let Crabby add photos again.

Then there are individuals who are less balanced. One individual may be 75% Type I and 25% Type II or vice versa. They are predisposed to excel in a particular type of activity, whereas the more evenly balanced individuals will be good at both kinds of activities (and some sports like say soccer). More Type I than Type II will naturally excel at endurance oriented events. Switch it and you have a great linebacker, 100 m sprinter or running back in football. Of course, the percentages vary, but they influence our ability to gain muscle mass, efficiency in oxygen utilization at the cellular level, excel in different types of sports or activities.

But, coming back to the original question: muscle tissue composition will also dictate which substrate (carbs or fat) we like to use both at rest and during exercise.

In general, Type I muscle fiber tissue likes to burn fat as a fuel source when it is activated, and Type II likes to burn carbohydrate as a fuel source when it is activated.

So how can we tell the difference between Type I and Type II muscle fiber tissue, and what happens when we exercise?

Enzyme concentration and number of mitochondria are a piece of that puzzle. Type I has a lot more mitochondria…and you know what mitochondria do? Mitochondria help the cell utilize oxygen efficiently and the energy system that primarily can burn fat as a substrate is located within the mitochondria.

Type II muscle fiber on the other hand has way fewer mitochondria, doesn’t require oxygen to provide energy (hence their anaerobic nature) and have lots of enzymes to breakdown, you guessed it: glucose (or carbohydrate).

But what happens when say someone who happens to have more Type II muscle fiber tissue trains to run a marathon? This is where epigenetics comes into play. By training more aerobically, some of the Type II muscle tissue will start to become more like Type I muscle fiber tissue. Not all of it will convert and it won’t convert all the way but it will start adding mitochondria and fat burning enzymes while decreasing some of the factors associated with it being anaerobic. It will become more like Type I but to date there is no evidence it will become 100% Type I.

Now of course, muscle cells don’t just start adding more and larger mitochondria and fat burning enzymes, this has to initially happen at the genetic level. Once this individual stops training for the marathon, or completes it ideally and stops training for endurance, those genes will turn back off and back to the Type II muscle fiber tissue that is more, let’s say natural for that individual. This person, although well trained, will never be as efficient at endurance activities as the more Type I individual and there is some evidence, some people (up to 20% of the population) just don’t have the genes to convert at all. So regardless of all of the endurance training, they never increase the number or size of the mitochondria and can’t produce more enzymes for burning fat.

Why is this important? Well, when engaging in lower intensity, longer duration activities (even sitting at your desk) our bodies prefer to burn fat, how much fat will depend on genetics and muscle fiber type. Burn more fat at rest and during exercise = ability to consume more fat throughout the day.

It makes sense that someone with more Type I muscle fiber tissue will likely burn fat more readily than someone with more Type II, even if they train for endurance oriented activities both at rest and during activity. Ironically, our brains (which actually suck up a lot of daily energy needs) prefer carbohydrates (glucose) as does Type II muscle fiber tissue. So individuals with more Type II, even at rest are likely not very efficient at burning fat and prefer glucose. Which means those individuals likely would do better consuming less fat and more carbohydrates (the good kind of course).

Consumption of Carbohydrates, Fat, and Protein


We adapt to our environment.  Some better than others.  We can up-regulate and down-regulate hormones and enzymes, change cellular structure (which changes efficiency of substrate utilization), all by changing our activity patterns (Epigenetics) and something else: what we consume (Nutragenomics).



So a logical question is “If I consume less carbohydrate and more fat (and protein) will my body adapt by becoming more efficient at utilizing that fat; will I then burn more fat?  Again, if the genetics allow for it, yes!  If not, not so much.

It’s important to remember here that both your brain and your muscle tissue use about 20% of your total daily energy needs respectively and for the muscle tissue that only increases when you are active. So ultimately what kind of muscle tissue you have, or can shift via training will play a role in your ability to burn fats and/or carbohydrates efficiently both at rest and during activity.

The real problem with carbohydrates seems to be the kinds of carbs we are consuming in the standard American diet.  Way too much sugar and processed carbohydrates and way too few vegetables, fruits and whole grains.   That however, is an entirely different post.

Dr. Tiffany Reiss is an an exercise physiologist and adjunct faculty member at Seattle University, Lake Washington Institute of Technology, American Public University and Walden University. She is also a contributor for the Sports and Fitness Network and the co-founder of TheHubEdu: A Learning Library.

What do you guys think about carbs?

37 comments:

  1. I love reading all this stuff---but the older I get (waves cane) the more I realize I KNOW NOT WHAT WORKS FOR ANYONE ELSE BUT ME.
    for ME the processssed white does not work.

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    1. Carla, yep, exactly. This is what I am finding, too. I have been very gradually phasing it out, most of the time. I like pizzeria pizza too much to totally abolish it from my life. ;)

      Everyone has to figure out the best things to do for their body. There is no one size fits all.

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    2. No, there is no one size fits all and to make it even more convoluted, aging influences this as well. In general, we become less efficient at burning anything as we age due to a slowing down of metabolism and something called sarcopenia (a natural loss in muscle mass as we age).

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  2. You can have my carbs when you pry them from my cold, dead hands. :-P

    That said, this was an interesting read. I've seen epigenetics discussed a bit on the forums, but hadn't read any more about it until now. It really makes me wonder which type of muscle fiber I have and whether I can adapt it. Definitely something to look into, so thank you for the info!

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    1. In general, you can tell what type of muscle fiber tissue you have by how you respond to the various activities. If you respond really well to endurance training, likely more Type I. If you see better results from resistance training or engaging in HITT, likely more Type II. If you see good responses from both: you are a good combination. You can have a muscle biopsy if you are really interested....but you get a cut on the leg and a clip of your muscle tissue removed. Not recommended unless you are really, really interested: http://vetneuromuscular.ucsd.edu/cases/2002/images/jul02image003.jpg

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    2. Yeek, not THAT interested! No more cuts this year, the last one is still healing up. ;-)

      Considering the data I have, I think I'm a combination leaning slightly toward Type II. I respond really well to strength training and am making decent progress on the endurance stuff (cycling). After reading this, I'm going to start keeping a closer eye on my progress to see which is optimal. Thank you!

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  3. My instinctive response to this debate is to say "Eat what you like best, just not more of it than you need." Then I pay attention to what a lot of people actually LIKE, and throw up my hands. Thanks to my allergies, I eat very few processed foods (too many micro ingredients I'm allergic to: soy is in Everything!) and I just don't like the taste. Let's take Cheetos as an example. I've eaten a few at parties, and thought "Blechhh!" Yet they're one of the snack foods a lot of people say they find irresistible.
    " Way too much sugar and processed carbohydrates and way too few vegetables, fruits and whole grains. That however, is an entirely different post." It's one I want to read!

    Mary Anne in Kentucky

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    1. I'm sorry you have to deal with allergies, Mary Anne. You're right about the micro ingredients. We've been working in less processed stuff to get more accurate calorie counts, so I'm more focused on labels now, and the amount of weird ingredients stuffed into some food is just incredible.

      Our tastes have changed as we've eaten this way, too. I used to be a complete fiend for Starburst candies and now they taste like Play-Doh dipped in fruit juice. It's a bit of a bummer, but now that's one less thing to waste my limited willpower on. I still love a good Cheeto, though. :-P

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    2. "Play-Doh dipped in fruit juice" just nails it!
      I don't have to waste my will power on anything but not eating All the Ice Cream in the World.

      Mary Anne in Kentucky

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    3. Ice cream, oh yes. That is a valid use of willpower. High five!

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    4. Yeah, It's a good thing that Cheetos are that radioactive orange color. It makes it easier to convince myself they are actually poison yummies.
      By some miracle I have no Ice cream addiction! I don't know how I missed that one!

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    5. Perhaps Crabby will let me write that "entirely different post"!

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    6. I suspect you'd be preachin' to the choir re: "way too much sugar and processed carbohydrates" Tiffany, but we love your researchy posts. And perhaps you could break through that "I know what I should do but I ain't doing it" resistance some of us have by scaring the crap out of us? :)

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    7. Oh, Mary Anne - I will eat all your Cheetos - they are one of my biggest weaknesses!!!

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    8. Death Ride GrandmaJuly 31, 2014 at 12:41 AM

      And I will keep you from eating all the ice cream in the world - by eating an excessive share of it myself!

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    9. Ice Cream Mavens of the World, unite!

      Mary Anne in Kentucky

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  4. I have been trying to eat more whole, unprocessed foods, many fewer simple carbs, many more complex ones. I'm also trying to up the protein intake and not worry too much about fat intake (though again, focusing on "good fats"). I tell you what, it seems to be a very good prescription for me! The weight is not falling off, but it is steady more or less, AND I feel better. I've noticed my taste buds and cravings adjusting accordingly, too.

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  5. This is interesting because I always wondered why I didn't seem to get much bang for my buck in weight loss when I would take up regular heavy cardio, but weight lifting would seem to do the trick. I figured it was stress. That I found cardio stressful and that was sabotaging my efforts. Probably was a factor along with what type of muscle fiber I have.

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    1. Yep. From what I've learned and experienced, it's the strength training that is really beneficial. I don't know the exact science behind it, but articles like this help! ;)

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  6. Very interesting read. I myself enjoy my carbs, but I eat smarter carbs and not processed stuff to get them. We recently met with a nutritionist who restricted us to less than 20% of our day to be carbs and I've been miserable. We're having tons of protein, which is (I think) the only thing getting me through my workouts, but I don't feel like I have much oomph to give. I think the guy is a hack anyway because when we asked him what to do after our initial 2 weeks (in which he had us literally following the same foods each day for two weeks) he tried to get us to buy some of the supplements he sells. He didn't seem like helping us after I told him I wanted to just eat real foods so he suggested restricting our calories even MORE (we're already in the 1400 range) since we didn't want to take the supplements. Not a great experience from someone we thought was a "professional". Now we're back to square one, not knowing if one thing or another we read online is accurate.

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    1. Courtney, you might look into his credentials to see if he's a Registered Dietitian. The educational requirements and accreditation process for Registered Dietitians are pretty strictly monitored, so you're more likely to get solid advice from them. From what I've read, almost anyone can hang a shingle as a "nutritionist," which opens people up to all forms of odious quackery. If your guy isn't an RD, I'd say ditch him and get a referral to one.

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    2. You're absolutely right, Heather. The only reason I even went to see him is based off a recommendation from the gym I go to, plus I got a discount through said gym. He is most definitely not an RD and I really wished my health insurance covered that type of thing. Thanks for the advice!

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  7. Dang it, will Cranky Fitness commenters please stop being so damn awesome while I'm trying to keep my nose out of the blog and attend to other things? It's my favorite thing in the world to read comments, especially when y'all do the back and forth reply thing.

    (And I hope I don't have to say just kidding?)

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    1. Nope. We're awful that way. :-P

      Now back to work, Crabby! *whipcrack*

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  8. Seems like a pretty well written article to me! Nice choice, Crabby!

    I do not eat breakfast because I do not want to break-the-fast, and so I think I stay in a high fat burning mode for a while every day. I have a very low body fat%.

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    1. I rarely eat breakfast either - sadly I don't have a very low body fat%! (maybe it's the Cheetos!!)

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  9. Great post & carbs get a bad wrap in IMHO... your ending is perfect & what I tell others.. it is not the carbs but the types of carbs people eat PLUS each of us if different so we have to find what works for us. Also - how active we are & what we do for that activity. :)

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  10. Carla's first thought was mine as well! Every human body is a little different, and each of us must experiment and figure out what works in each specific situation.

    For me, i like the way i eat now, almost 100% raw vegan (i will not give up my coffee, i'm from south Louisiana, it's part of my religion).

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  11. Low carb rules, low carb rules, low carb rules! For me! Wheeeee! Nothing gets me more excited than low carb, but of course, it is not for everyone.

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  12. Wow! This naked dude is getting absolutely no attention in the comments! Wrong crowd buddy you might as well just pull up your pants!

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    1. Next time, naked ice cream cones and cheetos, Cindy. What was I thinkin'?

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  13. I know and feel what makes my body hum ...protein ( meat eggs) and low carbs ( under 40 /day), veg, fruit and water. No processed foods no snacks never ice cream...wasn't raised with all that crap so never wanted it.

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  14. Great post! Love to hear the science behind it all!

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  15. Thank you for this informative and interesting post. I learned so much about my body and totally weight management.

    I think I'm a person of type I, as I'm enjoying everyday yoga for now. But I've to try other types of exercises as well to ensure what type of muscle fiber I have.

    My organism requires high protein and low carb nutrition from me, especially fresh fruits and vegetables. So I think every individual should listen to his body when including this or that food into their daily diet regimen.

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  16. I felt really ill when I cut my carbs back to Atkins levels. Even given time to get over 'carb flu,' I never felt right. I feel best on 100ish grams of carbs per day, but it has to come from things like fresh produce and not a bunch of sugar and grains.

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  17. I really love reading about how everyone knows what is good for their own bodies! I think this is invaluable!

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  18. I found this to be an interesting read and it makes a lot of sense to me: Humans are adaptable, we have different genetic make ups, different strengths and talents...Completely makes sense that there is no one-size-fits-all answer (I've been convinced of that for a long time).

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