Effect of Animal Fat on Sleep (more)

After the striking correlation I described earlier — I ate lot more animal fat than usual and slept longer and had more energy the next day — I started eating much more of what had produced the correlation: pork belly (which is used to make bacon). I couldn’t get uncured pork belly, so I ate bacon. I usually ate it raw. I tried several brands; the only one I liked was from Fatted Calf ($10/pound).

In Beijing I discovered pork belly for sale in every meat department. It is used to make a dish said to be Chairman Mao’s favorite. I bought a soup cooker, an appliance I haven’t seen in America, which made it easy to cook the pork belly. I seemed to sleep better when I had it for lunch.

Finally I did an experiment. I ate pork belly for lunch some days but not others. I ate the pork belly in miso soup, with vegetables. I always ate a whole package of pork belly, which was about 0.7 lb and perhaps 80% fat, 20% meat. On baseline days I ate my usual diet, which was already high-fat by people’s standards. (For example, I ate a lot of whole milk yogurt, a fair amount of nuts, and ordinary amounts of meat.) I tried to alternate baseline and pork-belly days but this wasn’t always possible.
Here are the results on ratings of how rested I felt when I awoke (100% = completely rested = the most rested I have ever felt, 0% = not rested at all).

The lines were fit separately to each set of points (red line to the red points, etc.). The difference is is very consistent (t = 5). Differences in how long I slept were much less clear. I will discuss them in a separate post.

The fascinating thing about this effect isn’t just how clear it is; it’s also how fast it goes on and off (within a day). With most nutrients you’d never see an effect like this. For example, scurvy takes months to develop and a few weeks to recover from. The omega-3 effects I’ve studied have a fast onset but take days to go away.

Sleep is controlled by the brain, of course. The brain is more than half fat, but determinations of how much fat the brain has have measured structural fat. This effect is so fast, both on and especially off, that it must involve circulating fat. Apparently my brain works better when there is a certain amount of animal fat in my blood. This supports Chairman Mao’s idea that pork belly is “brain food” but is a new idea for American intelligentsia. I think the chance that a nutrient that is good for one part of the body is bad for another part is zero — the same as the chance that the electrical appliances you own work best with widely-different currents. The obvious conclusion suggested by this data is that we need plenty of animal fat to be healthy. The only novel element of these lunches was the animal fat. Miso soup with ordinary meat has no effect on my sleep, as far as I know.

I think the science of nutrition proceeds in four steps, repeated over and over for each necessary nutrient: 1. Figure out that we need it. 2. Determine a way to measure how much of it we need. 3. Figure out the optimal amount. 4. Check your answer. With animal fat, conventional nutrition science hasn’t quite reached Step 1. Before this data, I’d say the clearest evidence that we need animal fat is that fat tastes good and long ago we had very little plant fat so it must have been the benefits of animal fat that produced the fat-tastes-good linkage. But conventional nutrition scientists never think this way — never take what we want to eat as meaning anything. And the mere fact that fat tastes good is no help figuring out how much is best.

This data pushes our knowledge toward Step 2. It doesn’t just suggest we need plenty of animal fat for best health, it also makes two methodological points: 1. Animal fat improves brain function. There may be better measures of the improvement than sleep quality. 2. The timing of the improvement — which as far as I know is unprecedented in the study of nutrition — makes it easy to measure.

Yesterday at a Carrefour I watched a pig being cut up. The butcher cut off the skin (with a thick layer of fat) and tossed it into a section of the display of pork for sale. I could buy the part of the pig I valued most for an incredibly low price (about 25 cents/pound). All other pork cost more. That’s how much Chinese shoppers wanted it. No one rushed to buy the newly-cut piece of skin. It reminded me of New York where I tried to buy food past its expiration date, ordinarily considered worthless.

29 Replies to “Effect of Animal Fat on Sleep (more)”

  1. It probably makes a big difference what the pig ate.

    We don’t call them “soup cookers”, we call them “crock pots” in the US.

  2. A soup cooker cooks food at a higher temperature (mine heats its contents to 204 degrees F.) than a crock pot — even a crock pot set on “high”. Crockpots cook food at 190 degrees or less, in my experience.

  3. Interesting. I have two concerns. First, I’d be a little leery of eating *too* much big fat in China. You’ve probably seen the bicycle/carts carrying slops from restaurants out to the suburbs (leftover food and oil) to be fed to pigs. Wonderful from an ecological point of view, but I worry that it might tend to concentrate noxious fat-soluble stuff in the pigs after you go through a few rounds of this.

    I also would be loathe to use Chairman Mao’s predilection for Hunan food as a recommendation for this, unless you want to also recommend some of his other habits (never brushing his teeth, sleep with a lot of young girls in his declining years) — probably all things that our Paleolithic ancestors would have done, or wanted to do, but maybe not things we’d endorse (alternatively: New fields for self-experimentation!).

    Sounds like you need to check out some Hunan restaurants. I can’t remember the name of the one we used to go to downtown, just off north Wangfujing (somebody’s family restaurant). I did find this pretty strong recommendation, although it’s bound to be very upscale, given the location:

    “2. KaraiyaS10-30, The Sanlitun Village,19 Sanlitun Beilu, Chaoyang District Tel 6415 3535
    辣屋 朝阳区三里屯北路19号三里屯Village, S10-30
    Karaiya, which means spice house in Japanese, delivers the superb flavors of Hunan by using quality ingredients with a modern twist. Spicy Pepper Diced Rib-eye, a must order dish studded with red peppers, is stimulating while at the same time not dominating the flavor of the meat. Also try deep-fried stinky bean curd. The concise bilingual menu is easy to navigate without having to plow through confusing page after page of dishes. The cheerful and pleasant environment makes Karaiya one of the best dining destinations in the capital.”

    We went hiking in Zhangjiajie once and had lunch on top of a mountain. There was one dish that had slices of what I thought was some kind of melon, but actually were pieces of fried pig fat. Having hiked uphill all day, it was quite delicious.

  4. Pork fat is also sold as ‘lard.’ Makes a great pie crust for apple pie. I remember my dad saying that back during the Great Depression, many laborers ate lard sandwiches for lunch…including both my grandfathers who were blacksmiths. Both died from heart attacks in their early 70’s. When you can no longer work off your daily intake, it might just start clogging your arteries. Best to monitor cholesterol etc.

    Lard went out of favor for baking with the advent of Crisco-like shortenings (partially hydrogenated soybean/vegetable oil). But partial hydrogenation creates a lot of transfat, which is now known to be a problem. The new Crisco has had much (but not all) of its transfat removed…but piecrusts made with it just aren’t the same (IMHO). Maybe lard will be making a comeback of sorts.

    I’ve found that when I’m wired and can’t sleep, a big bowl of potato chips works like a charm.

  5. Thehova: A whole pork belly and a couple fish oil caps are on completely different levels. You’re talking about adding 2-5 grams of animal fat to your diet; Seth is adding 255 grams (if the 0.7lb/ 80% fat figure is accurate), and significantly altering his macronutrient ratios.

    Seth: I’ve had the exact same experience. The more animal fat in my diet, the better I sleep, without exception.

  6. Carol, that’s an interesting point. Animal fat behaves more like a drug than a micronutrient, certainly. Macronutrients such as glucose can have fast on and fast off effects. But we don’t need glucose every day for anything to work properly.

  7. Seth or David: I can’t imagine the answer to this would be “yes,” since you are human beings with lives — but have you tried controlling for overall fat intake? i.e. is it clear that *animal* fat is critical? CTB’s anecdote suggests that any kind of fat might work.

  8. Please don’t eat any more raw pork.

    Trichinosis is a nasty little parasite. Rare in the US because of the sanitary way we raise our pork but common elsewhere. From the Mayo clinic

    “Mebendazole or albendazole can be used to treat infections in the intestines. There is no specific treatment for trichinosis once the larvae have invaded the muscles. The cysts remain viable for years. Pain killers can help relieve muscle soreness” The larvae can also invade the brain and internal organs. In case you are unconvinced about how nasty the parasite is you might want to find the YouTube video of a trichinosis worm that was removed from a woman’s brain. The woman lived in the USA. Note ” There is no specific treatment once the larve have invaded the muscles.”

  9. Seth: Seriously, hasn’t it occurred to you that maybe it’s not the pork fat itself that’s helping you sleep, but some minor component of it? Maybe you’re getting a measured-out dose of melatonin or some other hormone.

  10. Nathan, I agree, pork fat has many components, you are right that I don’t know which of them makes the difference. That’s a long way away — right now I’d like to figure out the best dose.

    David, yeah, me too. It’s great to be actually able to get data about this.

  11. Re: parasites, from wikipedia,

    “Bacon is a cured meat prepared from a pig. It is first cured in a brine or in a dry packing, both consisting largely of salt; the result is fresh bacon (also green bacon). Fresh bacon may then be further dried for weeks or months (usually in cold air), boiled, or smoked. Fresh and dried bacon must be cooked before eating. Boiled and smoked bacon are ready to eat, but may be cooked further before eating.”

    If the bacon’s ingredients include ‘smoke’ then it’s perfectly safe to eat – it’s already been cooked.

  12. Seth, Nathan Myers and Alrenou- All ready to eat pork products in the US are heated to at least 150 degrees, considered the safe temperature to kill all trichinosis parasites. 137 degress is the actual temperature at which the parasite dies but because of the possibility of uneven heating pork is heated to 150 degrees to provide a margin of safety. It is doubtful that a butcher in china has the same sort of rigorious QA that, for example, Hormel does. I think we all can envision a homemade smokehouse where the temperature does not get above 150 degrees. Drying or salting does not kill trichinosis. Once trichinosis gets into the muscle THERE IS NO CURE AND IT IS VERY PAINFUL !! Besides, there is no downside to cooking pork. Cooking does not hurt the flavor. Please, all of you, don’t eat pork that has not been cooked even if it has been “cured”

  13. I use an electric pressure cooker for soup. I imagine that the soup cooker appliance is motivated by the typical Chinese stove having fewer burners than a U.S. stove–is that right? Most U.S. stoves have 4, but in Japan we have 2, so an electric pressure cooker in effect adds a burner for me.

    Trichinosis only affects a dozen people a year in the U.S., which shows it’s not that easy to get, considering how many inept cooks there are. If you don’t worry about anthrax or black plague, you shouldn’t worry about trichinosis. I suspect Nile is a PETA guy, or an unsuspecting stooge of their scare tactics. Canada has higher rates from wild game consumption like bear meat.

  14. @Seth

    A recent discussion on PaleoHacks also broaches this subject. One of the PaleoHackers writes:

    “I’m convinced that many forms of mental illness, particularly things like depression, anxiety and insomnia, are caused in large part by not getting enough animal products in your diet — particularly saturated fat, which is a precursor for a number of hormones that affect mood and energy.”


    I happen to think the same.

  15. Cholesterol which comes from fat. Is a precursor to every hormone in your body. You need proteins, carbs and fats in every meal. More people are afraid of fat and are not eating fat and were getting fatter.

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