Ask The Macro Manager: Super-Low Carb Or Intermittent Fasting?

While the low-carb diets get shouted from the rooftops, intermittent fasting has been slowly gaining popularity. Find out how these two vanguard dietary schemes stack up!
Q

Low-carb diets seem to be king of the hill at the moment, but I've been hearing a lot about intermittent fasting lately. Which is a better fat-loss diet?

This is a great question. The two approaches are more similar on a biochemical level than most people would think. Both are low-insulin diets, meaning they provoke a minimal insulin response from your body. Both also qualify as demanding diets, because they're in dead contrast with the way most people eat and can require a drastic change in eating habits and priorities.

Let's break down the difference.

Low-carb, Not Low-fuel

When someone talks about a low-carbohydrate diet it could mean a lot of different things. It could simple be a low-starch diet, or it could meet more specific parameters, such as less than 100 grams of carbs per day, or less than 50 grams of carbs per day.

For clarity and comparison, I'm going to talk about very low-carb diets (VLCD), which could also be called a ketogenic diet. This type of low-carb diet contains less than 50 grams of carbohydrates per day.

The macronutrient breakdown of a ketogenic diet generally looks about like this:

  • Carbohydrates: 10 percent or less of calories
  • Protein: 25 percent of calories
  • Fat: 65 percent of calories

In a VLCD like this, fats provide energy, because they don't have the same hormonal impact as carbs. If anything, dietary fat can help accelerate the body switching from using carbs as a primary fuel source to using fat.

As you can see from the macronutrient breakdown, protein is slightly reduced from the traditional 30-40 percent often used by bodybuilders and dieters. This is because protein is insulinogenic and can interfere with the onset of ketosis, a state in which your body is cranking on fat as the primary fuel source.

However, even at this reduced level, the standard VLCD model provides adequate protein to preserve muscle tissue during weight training, while also stimulating protein synthesis throughout the day. This is one advantage that VLCD has over fasting.

When looking at total protein synthesis over the course of the day, you get a greater effect by spacing out your protein intake, as with a VLCD, as compared to eating a majority of your protein in one sitting, as is the norm with many intermittent fasting protocols.

"Very low-carb diets, also called ketogenic diets, typically contain less than 50 grams of carbohydtrades per day."

Cleaning house by fasting

Fasting has one potential over VLCD: It is connected with cellular autophagy. This is when your cells have to scavenge for fuel, and as a result they empty the cellular cupboards, consuming aging or damaged cellular parts and waste products. This "spring cleaning" process converts old cellular trash into amino acids, the building blocks of protein.

Autophagy is an important and necessary biological process which is accelerated by fasting. Even short-term fasts can spark cellular autophagy, though it's not sure how many hours it takes for the process to begin for any given person. That said, the role and impact of fasting-induced autophagy on general health and fat loss has yet to be determined, so I honestly can't point to any acute benefits it could provide.

Autophagy

Cellular "housekeeping." The process of self-digestion by a cell through the action of enzymes originating within the same cell. Ensures the syntheses, breakdown, and recycling of cellular components.

I recommend my clients using a VLCD rather than fasting. My interpretation of the science is that due to the consistent, repeated stimulation of protein synthesis that you get with VLCD, it is a superior approach when looking at overall improvements in body composition. However, if executed properly, both these systems should result in similar fat loss. The key when choosing a VLCD or fasting is to decide which will enable you to execute most consistently and efficiently in your lifestyle.


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About The Author

Author, speaker, and nutritional consultant Mike Roussell, PhD is known for transforming complex nutritional concepts into practical habits...

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fdmays

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fdmays

Bit confused. I look at IF as a lifestyle change, not a particular diet since I can incorporate any kind of diet, whether that be VLCD, carb cycling, etc, into a form of intermittent fasting. I don't see how IF can be compared to VLCD in any shape, form or fashion. In-fact, some may argue that IF can be used in conjunction with VLCD if your workout falls within your feeding window--25-30 grams of carbs before your workout and the remaining 25-30 after. Just my two cents.

Jan 15, 2013 6:51pm | report
 
Chopp3dOut

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Chopp3dOut

If you use Intermittent Fasting as a lifestyle change, your gonna have a bad time...

Jan 15, 2013 8:22pm | report
Superwaxer

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Superwaxer

I agree with this.It's nearly a year since I started IF and it's a part of my lifestyle now. It is one of the easiest eating regimes I have followed in my years of training and not nearly as difficult as people make it out to be. I feel super healthy too.

Jan 16, 2013 2:43pm | report
Holly444

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Holly444

agree with fdmays - I've only been doing Martin's Leangains intermittent fasting for about 3 weeks now, and I am aaaaamazed at the changes happening in my body. It's not a difficult lifestyle change either. Cutting carbs can make many people cranky by causing them to feel deprived. That's not necessary when IFing. You can still have some of your favorite foods and still see amazing results. My strength has also skyrocketed in every lift - I was shocked after a week at the improvement! I eat my largest meal after training - often around 1000 calories worth. I go to bed with a full tummy every night and wake up leaner and leaner. That's something you can't say about a low carb diet! It may not be for everyone - but hey, you won't know until you try it!

Jan 18, 2013 11:28am | report
1nTheProcess

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1nTheProcess

For me, I mostly used intermittent fasting as a convenient way to cut out convenient snacking, and get all my clean quality food in one feast of a meal after my night workouts. I experimented around a little and eating some egg whites or a peice of meat in the morning worked really well for me, especially since I'm prescribed adderall a diet suppressant anyways.

Sep 16, 2013 5:19pm | report
elzachary

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elzachary

Mike, can you post up a sample days 25/10/65 worth of nutrition? Thanks

Jan 15, 2013 8:19pm | report
 
jger13

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jger13

http://www.ketogenic-diet-resource.com/ketogenic-diet-menu.html

It's not quite those macros, but it's close

Jan 31, 2013 4:09pm | report
RoKeCo

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RoKeCo

Greg Plitt practices intermittent fasting, doesn't look like it has hurt his muscularity does it? Bad time I think not! That is according to his own addition.

Jan 15, 2013 8:36pm | report
 
Darknightbegins

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Darknightbegins

Mirin God Like Rep Power

Jan 16, 2013 1:49am | report
ExPwner

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ExPwner

Yeah, but I wouldn't say it helps it.

Reps for you, red brah

Jan 16, 2013 5:33pm | report
cldillmann1

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cldillmann1

staying in a caloric surplus or caloric defecit will dictate gaining or losing weight. Meal timing is irrelevant to body composition. Eat when you want and count calories while hitting minimum fat and protein intakes then fill in the rest of your calories with any of the 3 macros.

Dieting is this easy people

Jan 16, 2013 5:41am | report
 
HBDYWI

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HBDYWI

i agree. as long as you hit your macro numbers it doesnt matter

Jan 16, 2013 8:59am | report
Mudvayne24

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Mudvayne24

I agree and disagree... obviously the calorie count will dictate weight gain or loss, but ingested proteins (say whey protein) will only last about 3 hours in the muscle tissue. The rest that the body doesn't need to utilize at that time will be discarded. If you are looking to optimally put on lean muscle tissue, it would be ideal to have aminos in your bloodstream/muscle tissue at all times. If you eat once every 6-7 hours there will be periods where the muscle tissue will be without the aminos it may want to build and repair itself with. Just my 2 cents anyway!

Jan 16, 2013 2:57pm | report
Mudvayne24

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Mudvayne24

Also I believe that if you went from say 200g of protein per day to 400g of protein, and inversely took the carbs from 400g to 200g you would notice a decent difference in composition.

Jan 16, 2013 3:01pm | report
JFort93

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JFort93

I agree its all about calories along with cardio for extra leaning out.

Jan 16, 2013 9:19pm | report
kanelouis

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kanelouis

I know from experience you are wrong . I've tried many different diet plans and I.T. Was the only one I can maintain muscle while losing fat

Feb 13, 2015 7:48pm | report
BobTryingToDoIt

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BobTryingToDoIt

so basically if you are in a deficit even 65 % carbs 25 % proteins and10 % fats you'll lose weight, now give me my broscience Ph D

Jan 16, 2013 10:13am | report
 
JayCarter2300

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JayCarter2300

That's how I see it.

I like to go with:
Protein - 1gram/lb of bodyweight
Fats - 0.2grams/lb of bodyweight
Carbs - The rest.

Jan 17, 2013 3:02am | report
dragonnoa1

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dragonnoa1

IF can include taking BCAA's or EAA's throughout the day so that your muscles stay fed.

Jan 16, 2013 10:15am | report
 
kenethleclair

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kenethleclair

low carb works fast and is easy to do once you get the hang of it and comprehend that no carb is the goal and keep your calories 1800- 2000 per day.....always a few carbs slip in soaim for zero carb to keep it low carb....

Jan 16, 2013 10:49am | report
 
Askie

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Askie

Seems as though most people dont understand IF. Its basically an eating schedule and not a diet. As per some of the other posts have mentioned, its calories in v calories out, deficit to lose weight and surplus to gain. Personally its the best method for me, and thats the key, do what suit's you best. I lose 3 to 4 lbs a week without any problem. More energy, clear head, no fogginess like when I tried low carb. And basically you need to eat clean, and watch the calories. Oh and not to forget, big shout out to the Hodge Twin, making those gaaaaiiinnnnzzzz yyyeeeeaaaahhhhhhh

Jan 16, 2013 11:23am | report
 
Superwaxer

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Superwaxer

Yyyeeeeeaaahhhhh aalll kaaands o' gaaaiiiiiinz!!!

Jan 16, 2013 2:45pm | report
Beow

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Beow

I have noticed an interesting element to a lot of these nutrition articles lately claiming particular information. Unless I am completely blind, these articles have absolutely zero research behind them. I wanted to learn more about this particular topic and scrolled up and down the page way too many times and found zero referencess/sources--related articles are not references/sources. The numbers broken down in this article make no sense to me. I have read articles to where the carb allowance and fat intakes are completely different.
Just food for thought for the writers. Start listing your references and not related items. Some of us like to follow up on presented "research"

Jan 16, 2013 12:48pm | report
 
Malloryandrews

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Malloryandrews

Agreed, I really wish they would post their references. Gives their articles more credibility then someone just giving their "broscience" opinion.

Jan 18, 2013 3:44am | report
Holly444

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Holly444

Beow- I agree. I can't say much about low carb dieting, but if you'd like to read some excellent research on intermittent fasting, check out Martin Berkhan's blog at leangains.com. Read read read - good stuff there. :o)

Jan 18, 2013 11:37am | report
Showing 1 - 25 of 48 Comments

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