Friday, May 02, 2008

Does Ketosis Cause An Internal Rise In Body Temperature?

Low-carb burns fat, but can it lead to extra body heat?

Ooh, ooh, ooh,
I feel my temperature rising
Help me, I'm flaming
I must be a hundred and nine
Burning, burning, burning
And nothing can cool me
I just might turn into smoke
But I feel fine

--Elvis Presley singing "Burning Love"

Somebody's turned up the heat up in here and it's gotta be that low-carb diet I'm on, right? That's what everybody does with livin' la vida low-carb when something new happens to them after starting this way of eating--they blame it on low-carb! I mocked this notion in this blog post about an earache a couple of years ago, but what if there is merit to some rather strange side effects of following a controlled-carbohydrate nutritional approach? Hmmmmmm.

There are several things we KNOW will happen to most people when they begin the low-carb lifestyle: their HDL "good" cholesterol goes up, there is a marked improvement in mental health, for women it helps with reproductive health, blood sugar levels are stabilized, they end up having less acne, triglycerides plummet (a VERY good thing!), and so much more I could spend hours sharing with you about. But there are some things that can vary from person to person as one of my readers shared with me in a recent e-mail.

This 43-year old man starting cutting his carbohydrate intake beginning in January 2008 and has lost over 25 pounds so far. WOO HOO! He has really enjoyed this new low-carb lifestyle change, but was curious about an unexpected side effect that has been plaguing him with no apparent cause. Here's what he wrote:

Hey Jimmy,

After lots of searches, I'm having trouble finding out if anyone experiences a sensation of a rise in body temperature while in ketosis. There are some days I feel like I am literally burning up (but I don't have a fever or anything). Coincidentally, usually the next day after this happens, I am down another pound. It's like the hotter I feel, the faster I lose weight.

Is this a side effect of my body burning stored fat and an increase in my metabolism? I'm having a hard time finding an answer in any literature I've read. Thanks for your time!

What an awesome question! Before I started livin' la vida low-carb weighing in at over 400 pounds, I was ALWAYS hot. HOT HOT HOT with sweaty palms and underarms all the time. I felt like I was on fire all the time. But when I went on the Atkins diet on January 1, 2004, I noticed very quickly a cooling effect happening within the first few months. At first, it was kinda weird when I wouldn't sweat anymore. I REALLY liked that because it was so incessant for most of my life.

But then when I'd shake someone's hand, I could tell my hands were much colder than everyone else. It was as if someone turned the thermostat inside my body down to extreme cold when I started livin' la vida low-carb and it still happens to me to this day especially when I drink a lot of water. And the funny thing is the water doesn't even have to be cold for this to happen. Strange, I know, but that's my experience.

So when I read this e-mail asking about getting HOTTER because of the fat-burning effects of ketosis on a low-carb diet, I didn't know what he was talking about since that wasn't anything close to what I dealt with. I had my suspicions about what may be causing it and shared those with my reader:

GREAT QUESTION! I suspect the ketosis is causing the rise in your body temperature because of the fat-burning that ensues in this state.

But rather than guessing and assuming at what the reason for this is, I decided to throw this question to a handful of my low-carb expert friends to see if they had any insights or practical experiences to share with us about this phenomenon. We'll hear from Jackie Eberstein, Dr. Jonny Bowden, and Dr. Richard Feinman with their responses.



I'm at a loss. I've never heard of nor have I experienced this one. As far as I know, there is no mention in research either that I recall. Sorry I can't be more helpful.

That's okay, Jackie! Although having worked with Dr. Robert C. Atkins for three decades treating all kinds of patients with a low-carb dietary regimen, I'm surprised something like this hasn't come up at least a few times. Interesting. Let's see what Jonny Bowden has to say.


Hi Jimmy,

I have never actually heard of that happening, but it absolutely passes the "smell test" to me. In fact, when you stop and think about it, this makes total sense on both an intuitive and a biological level.

I suspect what's happening is that thermogenesis is raised in the body, meaning the furnace temperature is up, fat-burning is accelerated, and that is why your reader is experiencing a temporary rise in body temperature. My guess is you are absolutely right about why this is happening.

It certainly makes sense despite my own personal experience. If you are burning fat, then that could cause an increase in heat which leads to an elevated temperature. Finally, let's talk to a biochemist who really knows his stuff--Dr. Richard Feinman from SUNY Downstate Medical Center in Brooklyn, NY and the co-editor of the Nutrition & Metabolism journal.


There are reports in the literature of this kind of observation by subjects in trials of high-fat diets. Little is known, however, of what controls perception of heat and the relation to food consumption.

The phenomenon of diet-induced thermogenesis or thermic effect of feeding (the old name for this was "specific dynamic action"), however, is well known and it is generally agreed that, at least under experimental conditions, consumption of 20% of protein calories, 5% of carbohydrate calories, and 3% of fat calories is "wasted" in increased heat production.

See, for example this 1984 study:

Karst H, Steiniger J, Noack R, Steglich HD: Diet-induced thermogenesis in man: thermic effects of single proteins, carbohydrates and fats depending on their energy amount. Ann Nutr Metab 1984, 28(4):245-252.

Abstract: The diet-induced thermogenesis of 12 healthy males of normal body weight was measured by means of indirect calorimetry over 6 h after test meals of 1, 2 or 4 MJ protein (white egg, gelatin, casein), carbohydrate (starch, hydrolyzed starch) or fat (sunflower oil, butter). The effect of 1 MJ protein was at least three times as large as that of an isocaloric carbohydrate supply.

In mixed meals there is little agreement because of the small number of studies and the fact that it is so complicated with other factors. For example, drinking cold water will increase heat expenditure. We certainly have the idea, supported by both experimental studies and anecdotal observations, that low-carb diets are less efficient at fat storage and that the missing energy may appear as heat. There is also the idea that the underlying mechanism can be related to ketone bodies but it would be impossible to say whether or not this is the cause in the case described by your reader.

So, the jury is still out on the question of whether ketosis brought on by a low-carb diet leads to an increase in body temperature. Has anyone else experienced this on your low-carb lifestyle? Or were you like me and started freezing when you decided to go low-carb? Share your comments about what you've experienced. Are you hot or are you not? :)

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Blogger Sarah said...

I found this winter the more fat I eat, the less the cold affects me. Actually, I have better tolerance for both cold and hot weather now.

5/02/2008 6:34 PM  
Anonymous Teresa said...

I have the cold. I feel colder then everyone else around me. Like you I used to be hot all the time until I started living lowcarb. It's nice to feel cooler these days..LOL

5/02/2008 7:09 PM  
Anonymous Anonymous said...

Jimmy, your readers' experience is very similar to mine. During my 50+lb low carb weight loss, I was hot all the time.

5/02/2008 7:44 PM  
Blogger Tom Bunnell (TB)--TB said...

A lady Journalist and Leader from India was a guest on one of the TV talk shows sometime back. -- She was asked if they really worshipped cows and thought of them as sacred. -- She said only in the sense that they made fertilizer to grow there food and that they were vital in that regard. She said that the cows themselves were to hot a food for them to eat.

She said that digesting meat in her country, which was mostly a desert type of hot climate with temperatures in the 100 degree range, would make them to hot in digesting it.

5/02/2008 11:31 PM  
Blogger swatkins said...

When I am truly in induction, then I have found I will get a bit warmer. I have watched for years, as I am always unusually cold, especially after eating. On the other hand my DH gets warm after he eats. I think it's my body trying to hold onto every calorie possible. I've always thought it was a very messed up metabolism.

5/02/2008 11:43 PM  
Blogger Amy Dungan (aka Sparky's Girl) said...

I'm always cold... no matter what. It's 75 degrees in my house right now and I'm cold. I'd LOVE to warm up during ketosis and wish that would happen to me. LOL

5/03/2008 2:48 PM  
Blogger HunBun said...

I've always been the freeze baby, colder than anyone else and my hands and feet are like ice 80% of the time or more. I have noticed that when I really need to eat I just can't get warm at all, so I take that as a signal that the furnace needs more fuel.

5/03/2008 2:51 PM  
Blogger PJ said...

Actually, I never asked anybody about this because it was so apparent in my experience that I assumed it was a given. My core body temperature definitely rises in relation to my degree of ketosis. Since I both have a lot more energy and am sweating more and hotter, I just always figured that was how it worked.

I admit, though, that this is sometimes complicated by a second factor--that often my deepest ketosis is when I am basically living on meat and my favorite veggie, peppers, and a lot of capsacin can have some heat effects as well (such as hot palms, which I actually thought was a ketosis symptom until I realized it was the peppers).

My normal body temperature is a full degree lower than the so-called norm, though. So I'm not sure if maybe the rise in temp is simply to normal or barely above -- something not easily measured except compared to myself. I've never actually taken my temp -- I've simply had the symptoms and assumed on it. Maybe I'll do that and see what the results are. If I can find a thermometer around here!

5/05/2008 12:17 AM  
Anonymous Anonymous said...

Thanks so much, Jimmy, for researching my question! And a special thank you to those who have commented thus far. It's nice to learn that I am not alone. What I have learned, I think, is that it might be a combination of factors which could be contributing to my experience. The best thing, besides losing weight and getting healthy, though, is that now when people say, "There goes one hot dude," as I walk by, they mean it.
Lee in Nashville

5/05/2008 10:47 AM  
Blogger JeffG said...

I have had the experience of feeling colder, especially to other people. As in, I don't feel cold, but when I touch myself or others touch me, I am less hot than the room I am in. I figured this was due to my blood pressure lowering or something like that due to the low-carb diet, especially since the sensation is similar (though less extreme) to the clammy feeling I have when I feel as though I'm going to pass out for some reason, just without the 'cold sweat'.

5/05/2008 11:34 AM  
Blogger Dawnella said...

Finally someone else is experiencing the body heat thing.
I have noticed this on several occasions while doing low carb. For the past two years I have been doing low carb. I hit a plateau about a year ago, and then the holidays came and I gained a shocking 30 lbs!!
I immediately went into low carb mode and like the first time I tried low carb, I experienced a very noticeable inner core burning sensation. Since jumping back into low carb I have lost 10 of the thirty I gained so far and pretty fast. In a little over a week. Im sooo glad someone else has had this. If you are cutting out carbs, ofcourse why wouldnt the body start using the stored fat? That is what low carb is all about..burning our stored fuel (fat) for energy.
I say this is a very very real side effect. Im shocked there isnt more info about it on the internet.
Thank you for finally bringing it out!!

5/21/2008 8:41 AM  
Anonymous Anonymous said...

Dawn, you described it very well, it fells like I am hot from the inside out. I too am glad I am not alone in this. It is encouraging to think that this heat is actually leading to weight loss (7lbs in two weeks so far). Since I am cold natured this is serving me well in an office full of hot natured people.

6/07/2008 4:04 PM  
Blogger Patsey65 said...

I am experiencing the same heating sensation. Like I am burning from the inside out even when sitting in an air conditioned room, at first I thought it was just hot flashes, but it wont go away, its been almost 14 hours straight. I hope this is the way my body is reacting to full blown ketosis, it feels like I've been working out the last 14 hours straight, which is fine with me. Wonder how hot I will be when I get done with my walk today?

6/11/2008 8:41 AM  
Blogger rebecca said...

i am one of the cold ones now!!! i used to be hot ALL the time but now, along with watching my caloric intake, i switched from beer to wine and almost immediatly noticed how cold i am-especially my hands. coincidence?? i think not.

2/17/2010 7:34 PM  
Anonymous Anonymous said...

Thanks for this info. I am experiencing a massive increase in body temperature. Yes, initially I thought it may be hot flushes but in the back of my mind I also questioned the process of burning fat resulting in this termperature rise. Other than that, I am feeling great so I am not concerned in any way, except that I live in Australia and it is really warming up. I am not looking forward to our full blown summer.

11/10/2011 5:43 PM  

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