Effect of Animal Fat on Sleep?

Recently I listened to Robert Spector discuss his book The Mom & Pop Store: How the Unsung Heros of the American Economy are Surviving and Thriving. He had a personal connection to the subject: His father was a butcher. “As I watched him trim the meat . . . ” he said at one point. I thought: Oh-oh. To “trim” meat is to cut fat off of it.

Last spring, I bought $80 of organic grass-raised pork from a farmer near Berkeley. My order included a variety of cuts.  I cooked the ones I was familiar with, leaving one I’d never seen before: pork belly. Pork belly is used to make bacon. I’ve never seen it for sale in America. Ugh, I thought. Fat. It’s 80-90% fat. I too trim the fat off meat. It sat in my freezer for a long time. Finally I decided I shouldn’t waste it. I cut it into chunks which I put in miso soup and had for lunch.

That night I slept much longer than usual (8.3 hr) and woke up feeling unusually well-rested. Here is a graph that shows my sleep duration for that night and several preceding nights:

2009-10-25 sleep duration and animal fat

Sleeping 8.3 hours was less common than this graph may suggest. I’d moved back to Berkeley in January and from then until the miso soup had measured how long I slept on 130 nights. I’d slept more than 8.3 hours on 2 of them (2%). Even rarer was how energetic I felt the day after the miso soup. I couldn’t quantify it, but it was very rare — once in 10 years?

Was it a coincidence — that on the very day I ate far more animal fat than usual I also slept much longer than usual and had much more energy than usual the next day? Or was it cause and effect? Here’s why the second explanation — which implies that for best health I need much more animal fat than I usually get — is plausible:

1. As Spector said, butchers cut the fat off meat. The odds that our Stone-Age ancestors, living when food was sometimes scarce, did the same thing: Zero. Perhaps our meat is unnaturally low in fat. If for a long time in our evolutionary past we ate a lot of animal fat it makes sense that our bodies would be shaped to work best with that much fat.

2. Many video games, which boys enjoy, resemble hunting. I think this reflects an evolutionary past in which men hunted. If so, for a long time humans ate meat. That they ate a lot of meat is suggested by the fact that when big game went extinct (probably due to hunting) human health got worse.

3. American culture demonizes animal fat. The conclusion that animal fat is bad rests on epidemiology. Once something becomes heavily recommended or discouraged, a big problem for epidemiologists arises: the people who follow the advice are likely to be different (e.g., more disciplined, better off) than those that don’t (the healthy-user bias). As I blogged yesterday, an example is vaccine effectiveness: Those who get vaccinated are different than those who don’t.

4. Fat tastes good. Which implies we need it. We like whipped cream, butter on toast, milk in tea, and so on. Butter vastly improves toast even with my nose clipped. Long ago, when this fat-pleasure connection evolved, dietary fat was mostly animal fat and fish oil.

All this makes it plausible that animal fat is good for us. That’s not surprising. Based on Weston Price’s observations plus these four arguments, I already believed this. Many people believe this. The interesting idea suggested by my data is the possibility of measuring its benefits quickly, by measuring brain function. My experience suggested that animal fat improves brain function quickly. Brain function is easier to measure than the functioning of other parts of the body. By measuring my sleep, my energy, or something else controlled by the brain, maybe I can figure out the optimal amount of animal fat. This is what happened with omega-3. The idea that omega-3 is good wasn’t new; the novelty was the ability to measure its benefits quickly. (At first I measured my balance, later other things controlled by the brain.) With a fast measure I could determine the optimal amount. It’s likely that what’s optimal for the brain is optimal for the rest of the body, just as all the electric appliances in your house work best with the same house current. If you figure out the best current for one appliance, you are probably simultaneously optimizing all of them.

25 Replies to “Effect of Animal Fat on Sleep?”

  1. I’d like to report that pork belly’s are available in America or at least they are in the midwest. They’re also available in California at least in the asian markets; I can’t comment on general markets since I’ve never looked for them there. However, I found most of the store packaged variety contain too much salt at least according to my test, so I still have to ask the butcher for them.

  2. According to the chart you noticed this effect in July — have you gathered more data to support or reject this hypothesis in the interim?

  3. You mention “grass-fed” pork. So, when you are talking about animal fat being good for you, is your theory that only grass-fed (high in omega-3) and not corn-fed meat would have the positive effect?

    Also, what about the supposed links between meat consumption and cancer?

  4. Animals, including all their fat, are the species appropriate diet of humans. I eat mostly that and I have never felt and performed better.

  5. Max, I already get plenty of omega-3. It wasn’t the omega-3 in the fat that made the difference. As for the supposed links between meat consumption and cancer, I’ll trust my experiments over epidemiology any day of the week. I’m not saying what I’m posting here is the final word, of course not. I am saying that it suggests the subject of how much animal fat to eat may be subject to experimental investigation.

    MT, yes I have gathered more data. I will eventually post it.

  6. Regarding your first point about the historical levels of fat in our human diets, one of the theories I’ve read is that we would have evolved scavenging first, and had a particular advantage cracking open the skulls of carrion due to our ability to use tools — which other scavengers lack. This would give us access to the brains, which are 60-70% fat (mostly saturated), and may have contributed to our rapid evolution to hunters with our shorter digestive tracts and our own larger brains. It does seem likely to me that higher levels of animal fat in the diet is healthy.

  7. Hi Seth – I just heard about this thing called the “fitbit” which can track your sleep while you wear it. I guess it has some kind of algorithm for figuring this out from your movement so it lists how long you laid in bed before sleep plus actual sleeping. It also tracks movement like a pedometer but is supposedly more accurate. It might make some of this data collection easier for you and be a useful tool for self-experimentation if it actually works well.

  8. I didn’t realize pigs ate grass. They’re not ruminants like cows, goats, and sheep. They’re domesticated from forest-dwelling omnivores (just like humans) with a diet much closer to humans.

  9. I don’t remember you mentioning whether your sleeping habits are such that you don’t usually accumulate sleep debt. I’m assuming this is the case, based on your descriptions of your general sleeping habits. I’m saying this because sleep debt, if it’s anywhere near significant, has far greater effect on alertness than anything else.

    Also, how well-rested one feels right after waking up is not necessarily a good measure of the quality of the sleep. Say when one has significant amount of sleep debt and starts to sleep it back, one starts to feel more drowsy in the morning for a while, but the day-time alertness still increases.

    In general, all of these effects on the feeling on “well-restedness” in the morning probably require one to be close free of sleep debt. I’d guess someone with significant sleep debt wouldn’t notice any effect from, say, standing on one foot just because the effects of the sleep debt would mask any other effect.

  10. Note that its grass fed organic pork. I ate a grass-fed beef meal a month ago and it was immediately casually apparent to my wife and I that the subjective well-being afterwards was much greater than it would have been after a typical beef meal.
    Also, I’d note that pre-domestication, wild animals had much less fat than today’s domestic animals have. It’s probably pretty close to nutritionally optimal to eat bison in the natural ratios of all of the meats they are composed of.

  11. Seth:

    You can indeed get pork belly pretty easily at lots of places here in the south Bay Area (Lunardy’s is a favorite here in San Jose). At any rate, a friend & I cooked some up a few weeks and it was excellent. We’ve since done it again. Pics:


    I can definitely attest to the benefits of high animal fat (I average 70% energy from natural fats). While I have not logged my sleeping hours, I do know that I sleep far, far longer on average than ever before in my life. I used to average 6 hours per night and now it’s about 7-8 almost every night. And very restful sleep.

    Another very welcome change over the last couple of years I’ve gradually upped the fat in response to feeling better and better as I have done so is that I can now enjoy laying in bed in a kind of “drift in & out” thing. I could never do that before. I would get antsy and have to get up. It’s quite enjoyable now to be resting but not asleep in the early morning.


  12. Aaron, thanks for the correction. Michael, the pig was raised at a boutique small farm but it wasn’t actually grass-fed. What you say is very interesting, though. In Beijing I can compare high- and low-priced pork, which corresponds to the distinction you’re making.

    Jarno, that’s right, I don’t have any sleep debt. I always sleep as long as I want.

    Richard, that’s great to know about the connection between your sleep and your change in diet.

  13. Seth – did you cook the pork belly pieces before putting them into your miso soup? If not, do you imagine I would experience a similar benefit by dropping raw fatty bacon into my soup, or perhaps rendered bacon fat?

  14. Ashish, yes, I cooked the pork belly pieces for a long time before adding the uncooked miso. The miso is added last and not cooked at all.

    I suspect raw bacon has the same benefit. In America, where I couldn’t get pork belly, I often ate raw bacon, although only certain brands were acceptable. I think the bacon is fine because the large surface/volume ratio makes it easy to digest.

    Yeah bacon fat should have the same effect. Except you’d need a lot of it. I think it is hard to eat pure fat but a bacon-like ratio of fat to meat is acceptable.

  15. Is it animal fat itself that is good for us? Or is animal fat a carrier for nutrients that are hard for our bodies to source elsewhere?

    The way I see it, humans probably ate a good bit of animal fat for most of their pre-history (until agriculture became widespread). Natural selection, therefore, had time to optimize humans for an environment in which animal fat was consistently part of the diet, and humans may have become dependent on some of the things that animal fat provides in abundance but other food sources do not.

    In the last few millennia, if humans stopped eating animal fat, or if the nutrient composition of that fat changed (say because the animals in the human diet became farm raised and grain fed), natural selection would not have had enough time to optimize humans for the changes, and, as a result, humans on a modern diet wouldn’t get enough of the nutrients they used to get from eating the fat of wild animals.

    So, adding some animal fat to your diet, especially if that fat approximates the fat of wild animals of yesteryear, is very likely to provide your body with some nutrients you’re not getting enough of in modern times.

  16. Seth, I found this relevant discussion on Ryan Koch’s Matters to Me blog (http://ryan-koch.blogspot.com/) post in which he discusses a Farley Mowet book “The People of the Deer” describing Mowet’s life among a group of Inuit.

    “It doesn’t take Mowat long to identify the key ingredient of the Ilhalmiut diet: fat. From his own experience on lean meat for an extended period of time, he describes the vast importance of fat in an all-meat diet through his battle with an affliction which he names, for want of a better term, mal de caribou, also known by a great many arctic explorers, prisoners of war, and human carnivores as rabbit starvation:

    … persistent diarrhea was only part of the effect of mal de caribou. I was [also] filled with a sick lassitude, an increasing loss of will to work that made me quite useless …

    Mowat’s guide — a half-Eskimo, half-white man named Franz — prepared and administered a peculiar remedy:

    … he took out a half-pound of precious lard, melted it in a frying pan, and, when it was lukewarm and not yet congealed, he ordered me to drink it. Strangely, I was greedy for it … I drank a lot of it, then went to bed; and by morning I was completely recovered … I was suffering from a deficiency of fat and did not realize it. (p. 88)”

  17. Crazy coincidence…I posted on your boards this morning about starting a carnivorous diet (zero-carb, mostly meat), and one of the more surprising side effects was improved sleep. After a few days of 60-70% animal fat/ 30% protein and negligible carbs, I sleep like a little baby.

    There’s a small community of people (http://zerocarbforlife.com/) out there that believe that all your body needs is meat and water. I’m not sure if I agree with their fanaticism 100%, but testing their theory makes for an interesting experiment.

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