2

votes

Question about Fat burning?

Answered on August 19, 2014
Created May 11, 2012 at 4:50 PM

So let's say you are in " fat-burning mode ". If you were to eat carbs while you already fat-adapted what would happen. Basically what happens to carbs when you have been eating a VERY low-carb diet for months. Will you oxidize and you those carbs for energy or not because your preferred fuel will now be fat.

E5c7f14800c5992831f5c70fa746dc5c

(12857)

on May 13, 2012
at 12:49 PM

You can up regulate ketones with low carb/starvation diets but glucose is the preferential fuel for most cells. Certain organs like the heart prefer saturated fat as fuel.

1edb06ded9ccf098a4517ca4a7a34ebc

(14952)

on May 12, 2012
at 10:47 PM

You can still burn fat and be out of ketosis.

543a65b3004bf5a51974fbdd60d666bb

(4493)

on May 12, 2012
at 03:40 AM

And ketone bodies can replace up to about 70% of the brains glucose requirement; "After the diet has been changed to lower blood glucose for 3 days, the brain gets 25% of its energy from ketone bodies. After about 40 days, this goes up to 70%" http://en.wikipedia.org/wiki/Ketone_bodies

543a65b3004bf5a51974fbdd60d666bb

(4493)

on May 12, 2012
at 03:40 AM

From what i have been able to gleam, there are some things in the body whose sole energy source is glucose. From what i have read these include; the testes, erythrocytes, kidney medulla, lens and cornea which are dependent upon glucose as their sole energy source. Gluconeogenesis can meet these glucose requirements. Not sure about the nervous system/nerves (glucose sole or primary source?)

15e5f57b981183b21fff26ce815bf93f

(444)

on May 11, 2012
at 05:35 PM

Well corrected, apparently some tissues such as cardiac cells are in fact reported to preferentially burn ketone bodies.

E7e7e1c856d4494d4a1b700b6869df90

(982)

on May 11, 2012
at 05:20 PM

hmmm I would not say it "prefers" sugar to other fuel. Most tissues actually "prefer" and do better with ketones as the primary fuel. If you eat too many carbs over an extended period (like a carb binge over several days/weeks)you can knock out of fat burning mode and must begin again..otherwise those carbs are typically stored as fat. It depends very much on your particular metabolism and insulin state/health-how many carbs and for how long.That is why a hi carb hi fat diet really puts the pounds on..it is not from the fat(as lead to believe-by the"authorities") but from the excess carbs.

3aea514b680d01bfd7573d74517946a7

(11996)

on May 11, 2012
at 05:18 PM

"Prefer" is a loaded term, although you might have meant it without any loading, lol. The body will oxidize alcohol first, then sugars, then other macros. It could just as easily be said that the body gets rid of the most toxic inputs first.

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3 Answers

2
64433a05384cd9717c1aa6bf7e98b661

(15236)

on May 12, 2012
at 02:48 AM

Your blood sugar will stay elevated longer because your body will likely have gone into a state of physiological insulin resistance so that your brain can get a higher amount of glucose. You will oxidize those carbs for energy, it just may take slightly longer.

2
15e5f57b981183b21fff26ce815bf93f

(444)

on May 11, 2012
at 05:10 PM

Fat-adapted or not, the human body will always prefer sugars to other fuel.

3aea514b680d01bfd7573d74517946a7

(11996)

on May 11, 2012
at 05:18 PM

"Prefer" is a loaded term, although you might have meant it without any loading, lol. The body will oxidize alcohol first, then sugars, then other macros. It could just as easily be said that the body gets rid of the most toxic inputs first.

E7e7e1c856d4494d4a1b700b6869df90

(982)

on May 11, 2012
at 05:20 PM

hmmm I would not say it "prefers" sugar to other fuel. Most tissues actually "prefer" and do better with ketones as the primary fuel. If you eat too many carbs over an extended period (like a carb binge over several days/weeks)you can knock out of fat burning mode and must begin again..otherwise those carbs are typically stored as fat. It depends very much on your particular metabolism and insulin state/health-how many carbs and for how long.That is why a hi carb hi fat diet really puts the pounds on..it is not from the fat(as lead to believe-by the"authorities") but from the excess carbs.

15e5f57b981183b21fff26ce815bf93f

(444)

on May 11, 2012
at 05:35 PM

Well corrected, apparently some tissues such as cardiac cells are in fact reported to preferentially burn ketone bodies.

543a65b3004bf5a51974fbdd60d666bb

(4493)

on May 12, 2012
at 03:40 AM

From what i have been able to gleam, there are some things in the body whose sole energy source is glucose. From what i have read these include; the testes, erythrocytes, kidney medulla, lens and cornea which are dependent upon glucose as their sole energy source. Gluconeogenesis can meet these glucose requirements. Not sure about the nervous system/nerves (glucose sole or primary source?)

543a65b3004bf5a51974fbdd60d666bb

(4493)

on May 12, 2012
at 03:40 AM

And ketone bodies can replace up to about 70% of the brains glucose requirement; "After the diet has been changed to lower blood glucose for 3 days, the brain gets 25% of its energy from ketone bodies. After about 40 days, this goes up to 70%" http://en.wikipedia.org/wiki/Ketone_bodies

E5c7f14800c5992831f5c70fa746dc5c

(12857)

on May 13, 2012
at 12:49 PM

You can up regulate ketones with low carb/starvation diets but glucose is the preferential fuel for most cells. Certain organs like the heart prefer saturated fat as fuel.

0
B3173217a49b5b0116078775a17eb21d

(11488)

on May 11, 2012
at 09:49 PM

Depends who you ask. Steve Phinney reckons that a single carb binge will knock you out of a ketosis, and you'll have to spend another 3 weeks keto-adapting. Mark Sissons reckons it only takes a day or two. I don't think that there is any good scientific evidence either way.

Whichever way, you'll get a huge BG and insulin spike, because your body downregulates the enzymes you need to digest the carbs.

1edb06ded9ccf098a4517ca4a7a34ebc

(14952)

on May 12, 2012
at 10:47 PM

You can still burn fat and be out of ketosis.

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