Thursday, May 9, 2013

Magical Research Shows Fat Makes you Sleepy

The Daily Mail has a story(1) about research(2) showing that a high-fat diet makes you sleepy. (See abstract 0977 in the research link.) This flies in the face of my experience and a whole lot of anecdotal experience, too (see the comments to the article). Since starting a low-carb, high fat diet, I haven't needed four-hour naps on the weekend. (See this, this, this, and this.)  I'm not exhausted come 7 p.m. on a Friday night. I have the energy at 44 that I should have had in my twenties. Are we low-carbers violating some law of physics or biology? No--the research and Mail article are magic tricks.

The article is called "Why the Atkins Diet will make you sleepy but a packet of crisps will wake you up." Atkins is a specific diet: 20 grams of carbohydrate per day during induction with adequate protein and fat; most of Dr. Atkins' patients couldn't go over 40 grams of carbohydrate per day without gaining weight. Yet the research article that it refers to doesn't mention the Atkins diet. It also doesn't mention what the participants were fed or how much carbohydrate their meals contained.

One magic trick that low-carb scare studies use is calling a medium-carb diet a low-carb diet. The journal article calls the meals "high fat"; it doesn't say whether the meals were also high-carb or high protein or something in between.

Another magic trick is studying a low-carb diet for less than two weeks, about the amount of time it takes to adapt to such a diet. The study in the journal was conducted over four days. It's not unusual to be a little tired for the first couple of weeks on a low-carb diet.

1. "Why the Atkins Diet will make you sleepy but a packet of crisps will wake you up"  by Emma Innes. Daily Mail, May 8, 2013.
2. "High Fat Intake is Associated with Physiological Sleepiness in Healthy Non-Obese Adults" by Kritikou I, Pejovic S, Vgontzas AN, Fernandez-Mendoza J, Bata M, and Bixler EO. Journal of Sleep and Sleep Disorders Research, Volume 36, 2013, Abstract Supplement, article 0977.


horfilmania said...

When I came across that article I snorted out loud and didn't even read it because my experience is the direct opposite.

But, hold on a sec, don't crisps also contain a lot of fat?

Lori Miller said...

According to, 100g of potato chips has 49g carb (net) and 38g fat.

If you're on a 2k cal per day diet, and your macronutrient ratio is 10% carb, 35% protein & 55% fat, that's around 50g carb & 122g fat. From that point of view, it's a high-carb snack.

If you're on a low-fat diet (10% fat on 2k cal per day), you're allowed 22g of fat. At 55% carb, you'd be allowed 275g of carb. The fat would blow your diet for the day.

Personally, I think of potato chips as a high-carb food, but it's relative to what your plan is.

Lowcarb team member said...

Speaking personally, my carb intake over the past few years is reduced and my fat in-take higher than it used to be and NO I am not falling asleep all over the place. Interestingly friends I sometimes go out with who have no regard to what they eat, or the blow out type meal they've just consumed, will often be asleep in their chairs for a couple of hours, and alcohol not necessarily the reason for this!
Lots more still needs to be done to cast out the LCHF myths, and re-enforce the good news.

All the best Jan.

Lori Miller said...

My mom used to go into "carb comas" that we couldn't rouse her from. We didn't know what was wrong with her. On a LC diet, she doesn't have those anymore.

Anonymous said...

If your brain is running on ketones (due to starvation or keto diet) it makes you mentally sharper.
If in the past our ancestors had run out of food, then their brains would be running on ketones (which provide more ATP to the brain per unit of oxygen used according to my monster book of metabolism). It is the ones whose brains worked well on ketones and could function well enough to hunt that would have survived.
It makes no evolutionary sense at all that a keto (ie high fat) diet makes you sleepy! Anyone who had that problem would have died out eons ago.
A high carb, high fat diet however is another thing entirely. Researchers don't usually know the difference between a high fat diet and a keto diet.

Carole AKA CarbsaneR

Lori Miller said...

That makes sense. It reminds me of a chapter in the book The Richest Man in Babylon: A man had ended up in slavery due to debt, ran away, and was crossing the desert back to Babylon. On the third day after his food ran out, he said he woke up with sudden mental clarity, hollered at his stolen camels to get up, and made it back home to tell the tale. Ketones FTW!

Galina L. said...

I am just seek and tired to encounter all that crap in the media. It doesn't harm me, of course, but makes it harder to try to give a saving advise to a struggling health-wise friend.

Lori Miller said...

If the comments are any indication, it looks like a lot of people know that LC scare studies are a load of crap.