# Butter and Arithmetic: How Much Butter?

I measure my arithmetic speed  (how fast I do simple arithmetic problems, such as 3+ 4) daily. I assume it reflects overall brain function. I assume something that improves brain function will make me faster at arithmetic.

Two years ago I discovered that butter — more precisely, substitution of butter for pork fat — made me faster. This raised the question: how much is best? For a long time I ate 60 g of butter (= 4 tablespoons = half a stick) per day. Was that optimal? I couldn’t easily eat more but I could easily eat less.

To find out, I did an experiment. At first I continued my usual intake (60 g /day). Then I ate 30 g/day for several days. Finally I returned to 60 g/day. Here are the main results:

The graph shows that when I switched to 30 g/day, I became slower. When I resumed 60 g/day, I became faster. Comparing the 30 g/day results with the combination of earlier and later 60 g/day results, t = 6, p = 0.000001.

The amount of butter also affected my error rate. Less butter, less errors:

Comparing the 30 g/day results with the combination of earlier and later 60 g/day results, t = 3, p = 0.006.

The change in error rates raised the possibility that the speed changes were due to movement along a speed-accuracy tradeoff function (rather than to genuine improvement, which would correspond to a shift in the function). To assess this idea, I plotted speed versus accuracy (each point a different day).

If differences between conditions were due to differences in speed-accuracy tradeoff, then the points for different days should lie along a single downward-sloping line. They don’t. They don’t lie along a single line. Within conditions, there was no sign of a speed-accuracy tradeoff (the fitted lines do not slope downward).  If this is confusing, look at the points with accuracy values in the middle. Even when equated for accuracy, there are differences between the 30 g/day phase and the 60 g/day phases.

What did I learn?

1. How much butter is best. Before these results, I had no reason to think 60 g/day was better than 30 g/day. Now I do.

2. Speed of change. Environmental changes may take months or years to have their full effect. Something that makes your bones stronger may take months or years to be fully effective. Here, however, changes in butter intake seemed to have their full effect within a day. I noticed the same speed of change with pork fat and sleep: How much pork fat I ate during a single day affected my sleep that night (and only that night).  With omega-3, the changes were somewhat slower. A day without it made little difference. You can go weeks without Vitamin C before you get scurvy. Because of the speed of the butter change, in the future I can do better balanced experiments that change conditions more often.

3. Better experimental design. An experiment that compares 60 g/day and 0 g/day probably varies many things besides butter consumption (e.g., preparing the butter to eat it). An experiment that compares 60 g/day and 30 g/day is less confounded. When I ate less butter, I ate more of other food. Compared to a 60 g/0 g experiment, this experiment (60 g/30 g) has less variation in other food. Another sort of experiment, neither better nor worse, would vary type of fat rather than amount. For example, replace 30 g of butter with 30 g of olive oil. Because the effect of eliminating 30 g/day of butter was clear, replacement experiments become more interesting — 30 g/day olive oil is more plausible as a sustainable and healthy amount than 60 g/day.

4. Generality. This experiment used cheaper butter and took place in a different context than the original discovery. I discovered the effect of butter using Straus Family Creamery butter. “One of the top premium butters in America, ” says its website, quoting Food & Wine magazine  This experiment used a cheaper less-lauded butter (Land O’Lakes). Likewise, I discovered the effect in Berkeley. I did this experiment in Beijing. My Beijing life differs in a thousand ways from my Berkeley life.

The results suggest the value of self-experimentation, of course. Self-experimentation made this study much easier. But other things also mattered.

First, reaction-time methodology. In the 1960s my friend and co-author Saul Sternberg, a professor of psychology at the University of Pennsylvania, introduced better-designed reaction-time experiments to study cognition. They turned out to be far more sensitive than the usual methods, which involved measuring percent correct. (Saul’s methodological advice about these experiments.)

Second, personal science (science done to help yourself). I benefited from the results. Normal science is part of a job. The self-experimentation described in books was mostly (or entirely) done as part of a job. Before I collected this data, I put considerable work into these measurements. I discovered the effect of butter in an unusual way (measuring myself day after day), I tried a variety of tasks (I started by measuring balance), I refined the data analysis, and so on. Because I benefited personally, this was easy.

Third, technological advances.  Twenty years ago this experiment would have been more difficult. I collected this data outside of a lab using cheap equipment (a Thinkpad laptop running Windows XP).  I collected and analyzed the data with R (free). A smart high school student could do what I did.

There is more to learn. The outlier in the speed data (one day was unusually fast) means there can be considerable improvement for a reason I don’t understand.

## 26 Replies to “Butter and Arithmetic: How Much Butter?”

1. Have you tried 90g/day?

1. Have you tried 90g/day?

Not for very long. It’s hard to eat much more than 60 g/day.

2. Chris says:

Seth,
Very interesting as usual. My interpretation is as follows:
Based on the Speed-Accuracy Tradeoff chart I estimate
Average time increased from 555 to 570 (60g vs 30g), a 2.7% decrease in performance.
Average accuracy increased from 30% to 21%, a 30% increase in performance.
Such a large improvement in accuracy with a minor decrease in speed would lead me to favor the 30g dose over the 60g dose.
Am I missing something?
Thanks for sharing and inspiring,
Chris

1. Such a large improvement in accuracy with a minor decrease in speed would lead me to favor the 30g dose over the 60g dose. Am I missing something?

Yes. As I say, when equated for accuracy, I was faster with 60 g/day. Accuracy is malleable. If I were slower I could easily be 100% accurate.

3. Chris says:

Maybe I should have expressed the accuracy improvement as an increase in correct answers 9/70 = 13%. 30g still wins IMO.

4. Tom says:

Seth, do you think that the effects of the Land o’Lakes butter are just as strong as with the premium (pastured) butter?

Do you have any interest in A/B/A testing a premium, grass-fed butter vs. Land o’Lakes? (Which I’m assuming is not butter from pasture-raised cows.)

1. do you think that the effects of the Land o’Lakes butter are just as strong as with the premium (pastured) butter?

Yes. I have switched between expensive and cheaper butters several times and never noticed a difference. Doing yet another test isn’t very attractive because there are too many things that are more likely to have an effect, such as sodium butyrate.

5. Andy says:

Hi Seth,

Stephen over at whole health source seems to be suggesting that butters healthful properties come from its buytrate content – http://wholehealthsource.blogspot.com/2009/12/butyric-acid-ancient-controller-of.html

I wonder if it is also responsible for its mind enhancing properties as well. Buytrate supplements are fairly readily available, maybe its time for Butter Mind 3!

Let me know what you think.

Cheers,

Andy

1. I wonder if it is also responsible for its mind enhancing properties as well. Buytrate supplements are fairly readily available,

Yeah, I’ve heard this idea. I plan to test it.

6. jon k says:

I’m interested in running similar experiments on myself with diet and other inputs (exercise for example). Question: Where do you find a program that records your trials, and are you manually inputting each data point to graph or can that be done automatically?

1. Question: Where do you find a program that records your trials, and are you manually inputting each data point to graph or can that be done automatically?

I wrote the program myself in R. R runs the experiment and plots the data. You can find much of the R code I use in this blog — look under R — but you will need to know some R to use it.

7. The easiest theory is that speed + accuracy is related to underlying arousal. (baseline arousal, potential arousal change). In which case it is hard to know which one is better slower or faster. If you had a composite measure for general health or general brain funcioning it would be better?

Note the ideas of “how to become smarter” book, he did lots of self experimentation on brain pformance, and found different foods for attention, concentration, socialization etc.

1. The easiest theory is that speed + accuracy is related to underlying arousal. (baseline arousal, potential arousal change). In which case it is hard to know which one is better slower or faster.

Increasing arousal does not make one faster at the same level of accuracy. It pushes you down (toward lower accuracy and greater speed) on a speed-accuracy tradeoff function. I observed that more butter made me faster at the same level of accuracy. Contradicting your theory.

8. Ps. I am convinced that butter quality matters. I feel it in my stomach immediately.

9. Joseph Buchignani says:

For your encore, you should try Ghee. It’s easy to make.

Using ghee should greatly narrow down what components of butter are producing the effect.

http://paleodietlifestyle.com/paleo-fats/

10. Nansen says:

In addition to butter, do you regularly consume oils (that is, when you’re not experimenting).

1. In addition to butter, do you regularly consume oils (that is, when you’re not experimenting).

I regularly consume flax seeds, due to their high omega-3 content. The omega-3 is entirely in the oil. Whether flax seeds are a better source of omega-3 than flaxseed oil I don’t know.

11. wcb says:

Seth, I have begun to employ your idea of consuming 1/4 or more stick of butter and have concluded there is great merit to doing this, if for no other reason than that it supplies the body with some healthy saturated fat. It’s also a great quick snack when melted in a cup in a microwave oven and topped with some grated parmeson cheese. You can eat it like soup. 🙂

1. You can eat it like soup

You can also put it in tea. In place of milk or cream.

12. Christian says:

Hello Seth, great discoveries. But, what about the cream? Is it not supposed to be the same type of fat as the butter? As I use to cook with butter and have cream on sauces and coffee this is an important question to know as to define how much milk fat I take during the day and its effects. Thanks¡

13. Greg Harrington says:

Seth, I have had a casual interest in trying this for a while, but I hadn’t figured out how to consume that much butter.

*You can eat it like soup.*

…did the trick!

I just “souped” half a stick of regular grocery store butter. I found it to taste *extremely* salty–much more so than eating it as a solid.

Do you use salted or unsalted butter?

14. Lisa Wainer says:

Hi Seth, Just a note from the other side of the pond. I wondered how you ate ‘half a stick’ of butter a day as I eat loads of butter but would struggle to eat half a ‘stick’. Now that I see the 60g measure it all becomes clear! In the UK a ‘stick’ of butter is 250g. I often make scrambled eggs with 30-50g butter as a way to get a good dosing per day. I am going to try the melted butter in tea (and hot chocolate) idea and see how it tastes – thanks.

15. Patti says:

Hi Professor Roberts,

I understand you are conducting the butter experiment for cognitive results.
I was wondering if you are self reporting any physical changes or noting any trends in blood work completed. Also, in conjunction with the butter what is the quantity of other fats you consume daily? (I am assuming you are still take a couple of tablespoons of ELOO)