Deeper Learning in Macroeconomics

Sarah Fine and Jal Mehta have a new book In Search of Deeper Learning. Their focus is on deeper learning in high schools. I want to explore the possibility of deeper learning in college macroeconomics.

What is Deep Learning?

In an interview with Liz Mineo for the Harvard Gazette, Jal Mehta defined “deeper learning” this way:

Deeper learning is the understanding of not just the surface features of a subject or discipline, but the underlying structures or ideas. If we were talking about a biological cell, shallow learning would be able to name the parts of the cell; deeper learning would be able to understand the functions of the cell and how they interrelate. 

When you listen to the show “Car Talk,” you are listening in on a conversation between someone who has a shallow understanding of their car and someone who has a deeper understanding. A person will call in and say, “My car tends to slow down when it rains.” And then one of the guys will say, “Well, does it happen more in hot weather or cold weather?” The caller can only see the symptoms; the person at the other end of the phone can see the system and has some underlying theory or diagnosis of what might be happening.

In the same interview, Jal also explains where and when deeper learning is most likely to happen:

… deeper learning tends to emerge at the intersection of mastery, identity, and creativity. Mastery is developing significant knowledge and skill; identity is seeing yourself as connected to doing the work; and creativity is not just taking in knowledge but doing something in the field. When those three elements come together, it often yields deep learning. …

When we visited schools, we asked students, teachers, and administrators to point us to the most powerful learning spaces in their schools. They frequently pointed to elective classes and extracurricular spaces.  

… we did a deep dive on theater and debate, and those were really different domains, but they shared a number of elements. It started with purpose — students knew why they were there, what they were trying to produce, and why it mattered. There was also a much stronger sense of community in extracurriculars; students described these places as like “family.” And there was lots of opportunity for student leadership as opposed to passively receiving knowledge. There was lots of intrinsic motivation and passion — that’s the identity and creativity parts of deep learning. But there was also a lot of careful feedback, practice, and refinement — that’s the mastery part. 

… the best core classes shared the same characteristics as the extracurriculars; there was a purpose created either by a project, an essential question, or by an authentic thing that was trying to be produced. There was a real attention to trying to build the right kind of community; there was a lot of peer learning by watching how other students were doing work or making comments.

Engaging with the Big Questions in Macroeconomics (or in Economics More Broadly)

At the University of Colorado Boulder,  I teach a class of about 100 students in Intermediate Macroeconomics. That stage of learning about macroeconomics and the sheer size of the class makes it difficult to assign a large term project that would force students to dig deeply into an issue in macroeconomics, but I give students the opportunity to dig deeply if they are willing to seize it. I assign weekly blog posts (on an internal class blog) that can be used to examine different angles of a given topic or to explore different topics. And even when a student explores ostensibly different topics in each blog post, I am a big believer that there is almost always a theme that answers the questions “Why am I interested in this set of things? What is the connection between them?”

In my view, the degree of personal initiative needed to seize the opportunity to make the writing assignments a deep learning experience is an appropriate level of personal responsibility for college as contrasted with high school. Those students who take that initiative will find the class much more rewarding.

Macroeconomics, in particular, offers many deep questions to wrestle with. Every day I see people wrestling with big questions in Economics Twitter. Here are just some of the big questions:

  1. What caused the take-off into modern economic growth?

  2. What policies and what political equilibria can get countries that are still poor onto the track toward getting richer as Japan, Southeast Asian countries, China and India have?

  3. Should fiscal policy or monetary policy take the lead in taming business cycles?

  4. How should monetary policy adjust to the increasingly frequent situations in which the short-term interest rate needed in order to provide enough stimulus is lower than the traditional zero interest rate on paper currency?

  5. What will it take to avoid another financial crisis like the Financial Crisis of 2008?

  6. What should we do about rising inequality? What are the side-effects of different ways of trying to address inequality?

  7. What is the best way of aligning the interests of corporations with the common good? Was Milton Friedman right in saying that telling them to maximize shareholder value will yield the best outcomes for the economy?

  8. What causes trade deficits? How could we reduce the trade deficit? Should we?

  9. Is immigration good for the economy or bad for the economy? If it is good for some people and bad for others, who is it good for and who is it bad for? How is the answer different when immigration policy is designed to shift the balance of immigrants to high-skill immigrants?

  10. How do labor market policies affect the economy as a whole?

  11. Have colleges lost their way? How effective are colleges at helping their students build human capital?

  12. How should we be evaluating the performance of governments? For example, should GDP be supplemented or supplanted by a National Well-Being Index? If so, on what principles should it be designed?

  13. In helping get people what they want, what is the right balance between the four main domains of the economy: the government, non-profits, for-profit activity, household production that is not exchanged in the market?

  14. Which economic regulations are bad and which are good? What are the essential economic regulations needed to effectively establish property rights?

  15. How can we slow global warming in a way that has the lowest cost to other economic objectives that we have? How can we build a political coalition to do that?   

Math and Deep Learning

In his examples of deep learning, Jal Mehta tends to give examples that are about thinking with words or honing words. And he talks about algorithms as if they were the antithesis of deep learning:  

The bad news was that in these schools, which had been recommended as places that did 21st-century learning or particularly rigorous forms of traditional learning, students still experienced a lot of unchallenging instruction; they were doing a lot of worksheets and tasks that were pretty low level, where they were expected to memorize content and apply algorithms rather than analyze, synthesize, and create.

For me, designing an algorithm is one of the true challenges for deep learning. Using an algorithm may or may not be an occasion for deep learning. The deep learning in relation to using algorithms is often about learning which algorithm to use in different situations, how to identify the inputs into the algorithm and how to interpret the numbers an algorithm produces. The algorithm itself may seem simple, without much depth, but once all of these challenges in using an algorithm appropriately are thought of as part of learning the algorithm, an algorithm can be an occasion for deep learning.

I teach many algorithms in my “Intermediate Macro” class because I think the questions of “What happens?” and “How much?” are essential for macroeconomics. As just one example of where the question “How much?” matters, there are many, many people on Twitter and in politics think they can get enough resources to do vast government programs from printing money. Seignorage, the effective government revenue from printing money, just isn’t that big. People can get very excited about something like seignorage because it is an unusual type of thing, but then overestimate just how big a deal it is, if they don’t do the arithmetic. Sometimes deep learning can be figuring out the difference between an effect existing and an effect being substantial in size.

Less is More

There is a tradeoff between deep learning and “covering” a lot of material. “Covering” a lot of material often amounts to a lot of time spent in giving the instructor the delusion that the students have a large set of ideas firmly in hand. True engagement by students requires taking longer for each key idea. Jal Mehta says this in his interview by Liz Mineo:

We define them as compelling teachers when they give their students a challenging, higher-order thinking task, and where at least three-quarters of the students were highly engaged with that task. … These teachers created spaces where they brought together rigor and joy and which were intellectually demanding, but also open, playful, and warm. … They emphasized coverage less and seeing things from different angles more.

Students as Scientists

Any deep learning requires students exercising their own minds in many ways. Jal says this to Mineo: 

Our most compelling teachers viewed their students as essentially inquirers in the subjects they were pursuing; the students were the historians or the scientists. They were trying to help students to own the standards of their fields or disciplines and also inspire them to get interested in their subjects in the long run.

… It takes time to develop knowledge, skill, and mastery over a domain, and these teachers were trying to get students excited about this trajectory.

In economics, the answers to many questions are still disputed, so taking the role of a scientist is not only a good way to learn, it is necessary in order to make a decision for yourself among competing ideas. Even when I only lay out only one view in my lectures, that view often differs enough from the view in the textbook or the view in an earlier class that there are plenty of different views for students to wrestle with if they are willing. A key here is to realize that a state of being confused is a gateway to deep learning.

What is wrestling with different views? It is asking the question of how someone could believe each view and then asking yourself what you believe after you have the backup for each view kicking around in your head. Euclid, who formalized the geometry you learned in high school thousands of years ago, is reputed to have said “There is no royal road to geometry.” I am saying “There is no road to deep learning that does not pass through a period of feeling confused.” Feeling confused along the way is not a problem. Thinking that feeling confused means you should give up is a big problem. I can tell you that cutting-edge research almost always involves going through a period of feeling confused. There is great honor in feeling confused because you are trying to understand something deeply.

Motivating Students and Making Things Fun

To me, economics is fascinating. I tend to teach as if everyone found it as intrinsically fascinating as I do. But I realize that, in fact, students come into my class with a wide variety of different motivations, almost none of which I understand. I would love to have more students tell me what it is they hope to get out of their Intermediate Macro class. If I understood better what interests my students come into the class with, I could thicken the connection of what we are doing in class those interests. Sometimes the connection might be that those interests stem from what I see as a faulty view of macroeconomics, but there should always be some way to connect things.

I would also love to have more students tell me what kinds of spice they like to have added to lectures. My primary goal will always be learning that lasts. But if, within my abilities, I can see how to make lectures more fun without sacrificing learning that lasts, I’ll try to do it.

Finally, I’d love to get feedback from other professors about what they think motivates students and what keeps things fun for students in macroeconomics. They might be interested in turn in what I have to say about my approach in “On Teaching and Learning Macroeconomics.” One possible motivation for wanting to learn macroeconomics is to be able to understand the newspaper as it talks about the big important events of the day. That is the objective for learning macroeconomics that, so far, I have been most focused on in my teaching.

 

 

 

 

Live Your Life So You Don't Need Much Self-Control

It is common to romanticize having a lot of self-control. But the best way to beat temptations is to keep them from happening in the first place. And most of us have a lot of control over that.

Reducing the Need for Self-Control over Eating

In the area of diet, one of the best way to reduce temptations is to go off sugar so that your body adjusts to not having so much sugar and sugar isn’t so tempting any more. I give a variety of tips for going off sugar in “Letting Go of Sugar,” but one obvious tip is to arrange a period of time when you don’t have anything sugary in the house. Depriving other family members of sugar for that period may generate some complaints, but it isn’t the worst thing in the world!

Beyond going off sugar, eating a low-insulin-index diet avoids the insulin backlash that would make you extra hungry. See “Forget Calorie Counting; It's the Insulin Index, Stupid” and “Obesity Is Always and Everywhere an Insulin Phenomenon.” Eating things high on the insulin index is a sure road to temptation!

If you are bringing fasting (periods of time with no food) into your repertoire in accordance with posts like “Stop Counting Calories; It's the Clock that Counts,” “Lisa Drayer: Is Fasting the Fountain of Youth?” “Jason Fung's Single Best Weight Loss Tip: Don't Eat All the Time” and “Andreas Michalsen on Fasting,” it will help to simply stay out of the kitchen as much as possible until your eating window. If food preparation has to take place outside your eating window, try to get someone else in your family to do it. For example, you might want to try to get someone else to make breakfast—perhaps by promising that you will only make healthy things for breakfast, like eggs or unsweetened oatmeal.

While fasting, it also helps to make a big ritual out of making coffee or tea, which are fine to drink when you are fasting. (If caffeine is an issue, you can use caffeine-free varieties.) Of course, don’t put sugar in it. And if you need a nonsugar sweetener, you need to be careful. Check out “Which Nonsugar Sweeteners are OK? An Insulin-Index Perspective.”

Aside from staying far away from temptation, try to consciously notice the tug of temptation when you get even medium close. Often, on my way to work, I pass by many restaurants. It makes me feel a psychological kind of hunger to pass by those restaurants. The temptation isn’t all that great, but I do notice the moderate tug that is there. Being aware of the tug of temptation when it is at moderate intensity can serve as a warning to stay away from more intense temptations.

Brian Resnick’s Vox article “The Myth of Self-Control” has some useful perspectives on self-control from psychologists. Here is some of what they say, all quotations from “The Myth of Self-Control”:

Quotations from Psychologist Kentaro Fujita

  • Effortful restraint, where you are fighting yourself — the benefits of that are overhyped.

  • Our prototypical model of self-control is angel on one side and devil on the other, and they battle it out … We tend to think of people with strong willpower as people who are able to fight this battle effectively. Actually, the people who are really good at self-control never have these battles in the first place.

  • The really good dieter wouldn’t buy a cupcake … They wouldn’t have passed in front of a bakery; when they saw the cupcake, they would have figured out a way to say yuck instead of yum; they might have an automatic reaction of moving away instead of moving close.

  • [Effortful restraint is] a defense of last resort.

Quotations from Psychologist Brian Galla

  • We don’t seem to be all that good at [self-control].

  • People who are good at self-control … seem to be structuring their lives in a way to avoid having to make a self-control decision in the first place.

  • Self-control isn’t a special moral muscle … It’s like any decision. And to improve the decision, we need to improve the environment, and give people the skills needed to avoid cake in the first place.

Quotations from Psychologist Marina Milyavskaya

  • There’s a strong assumption still that exerting self-control is beneficial … And we’re showing in the long term, it’s not.

  • ‘Want-to’ goals are more likely to be obtained than ‘have-to’ goals … Want-to goals lead to experiences of fewer temptations. It’s easier to pursue those goals. It feels more effortless.

The Marshmallow Test

All of this is in accordance with a finding in the famous marshmallow test. Here is Brian Resnick’s summary of that, with my emphasis added. :

Walter Mischel’s “marshmallow test,” conducted in the 1960s and ’70s. In these tests, kids were told they could either eat one marshmallow sitting in front of them immediately or eat two later. The ability to resist was found to correlate with all sorts of positive life outcomes, like SAT scores and BMIs. But the kids who were best at the test weren’t necessarily intrinsically better at resisting temptation. They might have been employing a critical strategy.

“Mischel has consistently found that the crucial factor in delaying gratification is the ability to change your perception of the object or action you want to resist,” the New Yorker reported in 2014. That means kids who avoided eating the first marshmallow would find ways not to look at the [marshmallow], or imagine it as something else.

Conclusion

The bottom line is this: don’t rely on self-control unless you have no other option. Try to live your life so that you don’t need much self-control. For example, if you have set a goal to avoid alcohol, don’t get within 100 feet of a bar. If a particular type of food is very tempting for you, don’t have any in the house. Schedule some fun distractions when you have set a goal to fast. Being smart in arranging your life makes it so you may not have to be strong.

For annotated links to other posts on diet and health, see “Miles Kimball on Diet and Health: A Reader's Guide.”

John Locke on Peace through Surrender to Tyranny


Overthrowing tyrants is a public good with much greater social benefit than private benefit. Hence, when there is genuine tyranny, it is a serious problem that individuals, encouraged by their family and friends, will put the private benefit of being safe from reprisals by a tyrant over the public benefit of helping to overthrow the tyrant.

But what about the cost to everyone of a civil war to overthrow a tyrant? Typically, those who actively work to overthrow a tyrant bear a disproportionate share of the direct cost of a civil war relative to their share in the benefits from a better government. And in their altruistic concerns, emotionally mature opponents of tyranny will be likely to weight the costs on others of a civil war fairly against the benefits of a better government.

It may be that some individuals gain a huge private benefit of perceived glory or identity confirmation from opposing a tyrant, and so may not strike the right balance. But a more common criticism those opposing a tyrant may face is that their altruism toward strangers is unusually strong compared to their altruism towards friends and family members who may also suffer reprisals from the tyrant.

In any case, except for selfish reasons (when one is, oneself one of the family and friends of the opponent to tyranny), it seems like only rare situations would justify discouraging someone from fighting against tyranny, even though there is likely to be collateral damage. The reason is that most opponents to tyranny do care about collateral damage and try to weigh the costs of collateral damage against the benefits of a better government.

Where those who style themselves as opponents to tyranny don’t seem to care much about collateral damage—as when they send suicide bombers to kill civilians—then one should suspect they have other motives than simply opposing tyranny.

John Locke does not discuss these tradeoffs in quite so much depth, but in Sections 228 and 229 of Chapter XIX, “Of the Dissolution of Government” of his 2d Treatise on Government: Of Civil Government, he does speak to the basic justice of fighting against tyranny even if there will be some collateral damage—but speaks of collateral damage in ways that are not very vivid: “destructive to the peace of the world,” “If any mischief come in such cases,” “inconveniences.” In this way, I think John Locke tries to make the issue of collateral damage look smaller than it really is. By contrast, John Locke appropriately speaks very powerfully of the benefits of overthrowing a tyrant:

§. 228. But if they, who say it lays a foundation for rebellion, mean that it may occasion civil wars, or intestine broils, to tell the people they are absolved from obedience when illegal attempts are made upon their liberties or properties, and may oppose the unlawful violence of those who were their magistrates, when they invade their properties contrary to the trust put in them; and that therefore this doctrine is not to be allowed, being so destructive to the peace of the world: they may as well say, upon the same ground, that honest men may not oppose robbers or pirates, because this may occasion disorder or bloodshed. If any mischief come in such cases, it is not to be charged upon him who defends his own right, but on him that invades his neighbours. If the innocent honest man must quietly quit all he has, for peace sake, to him who will lay violent hands upon it, I desire it may be considered, what a kind of peace there will be in the world, which consists only in violence and rapine; and which is to be maintained only for the benefit of robbers and oppressors. Who would not think it an admirable peace betwixt the mighty and the mean, when the lamb, without resistance, yielded his throat to be torn by the imperious wolf? Polyphemus’s den gives us a perfect pattern of such a peace, and such a government, wherein Ulysses and his companions had nothing to do, but quietly to suffer themselves to be devoured. And no doubt Ulysses, who was a prudent man, preached up passive obedience, and exhorted them to a quiet submission, by representing to them of what concernment peace was to mankind; and by shewing the inconveniences might happen, if they should offer to resist Polyphemus, who had now the power over them.

§. 229. The end of government is the good of mankind; and which is best for mankind, that the people should be always exposed to the boundless will of tyranny, or that the rulers should be sometimes liable to be opposed, when they grow exorbitant in the use of their power, and employ it for the destruction, and not the preservation of the properties of their people?

One of the interesting things John Locke is doing is to try to enlist a sense of honor and anger as motivations to oppose tyranny:

  • … they may as well say, upon the same ground, that honest men may not oppose robbers or pirates, because this may occasion disorder or bloodshed.

  • If any mischief come in such cases, it is not to be charged upon him who defends his own right, but on him that invades his neighbours.

  • If the innocent honest man must quietly quit all he has, for peace sake, to him who will lay violent hands upon it, I desire it may be considered, what a kind of peace there will be in the world, which consists only in violence and rapine; and which is to be maintained only for the benefit of robbers and oppressors.

  • Who would not think it an admirable peace betwixt the mighty and the mean, when the lamb, without resistance, yielded his throat to be torn by the imperious wolf?

  • … which is best for mankind, that the people should be always exposed to the boundless will of tyranny, or that the rulers should be sometimes liable to be opposed …

The thing I worry about most is people who don’t really know what the situation is in a nation and think they are nobly opposing tyranny, when given the facts on the ground they are doing something else. This is a manageable problem, but gets worse when there are people actively trying to deceive others into imagining a tyranny that is not there. (Of course, tyrants try to do the opposite: to get people to think there is not tyranny when there is.)

For links to other John Locke posts, see these John Locke aggregator posts: 

Paige Harden Defends `Genetic Endowments and Wealth Inequality' →

Here is the abstract for `Genetic Endowments and Wealth Inequality’ by Daniel Barth, Nicholas Papageorge, and Kevin Thom:

We show that genetic endowments linked to educational attainment strongly and robustly predict wealth at retirement. The estimated relationship is not fully explained by flexibly controlling for education and labor income. We therefore investigate a host of additional mechanisms that could account for the gene-wealth gradient, including inheritances, mortality, risk preferences, portfolio decisions, beliefs about the probabilities of macroeconomic events, and planning horizons. We provide evidence that genetic endowments related to human capital accumulation are associated with wealth not only through educational attainment and labor income, but also through a facility with complex financial decision-making.

Is the Bitcoin Algorithm a 'Robot Central Bank' or is Bitcoin Free-Market Money?


Kevin Thom Defends `Genetic Endowments and Wealth Inequality' →

Here is the abstract for `Genetic Endowments and Wealth Inequality’ by Daniel Barth, Nicholas Papageorge, and Kevin Thom:

We show that genetic endowments linked to educational attainment strongly and robustly predict wealth at retirement. The estimated relationship is not fully explained by flexibly controlling for education and labor income. We therefore investigate a host of additional mechanisms that could account for the gene-wealth gradient, including inheritances, mortality, risk preferences, portfolio decisions, beliefs about the probabilities of macroeconomic events, and planning horizons. We provide evidence that genetic endowments related to human capital accumulation are associated with wealth not only through educational attainment and labor income, but also through a facility with complex financial decision-making.

On 'Flipping the Metabolic Switch: Understanding and Applying Health Benefits of Fasting' by Stephen D. Anton et al.

Introduction

In “Andreas Michalsen on Fasting” I wrote

I’ll bet that in the environment of evolutionary adaptation our ancestors lived in before the advent of agriculture, involuntary fasting—that is, periods of time with little or no food—were quite common. As a result, many of our bodies’ systems were designed in a way that took as given that there would be frequent periods of little or no food. When people eat all the time, these systems don’t work very well.

In their review article “Flipping the Metabolic Switch: Understanding and Applying Health Benefits of Fasting,” Stephen Anton, Keelin Moehl, William Donahoo, Krisztina Marosi, Stephanie Lee, Arch Mainous, Christiaan Leeuwenburgh and Mark P. Mattson also argue from this perspective. (The remainder of the quotations in this blog post come from their article.)

Many animals in the wild regularly experience extended time-periods with little or no food. For example, packs of wolves living in the Northern Rocky Mountains of the United States typically kill prey, such as deer, elk or bison only once every one or two weeks. Their success depends upon their brains and bodies functioning at a high level so they can work with their pack mates to ‘formulate’ and execute a strategy to capture and kill the prey animal.(28) … Accordingly, those individuals whose brains and bodies performed optimally in a food deprived/fasted state would have a survival advantage.

Knowledge of early human evolution and data from recent studies of hunter-gatherer societies suggest humans evolved in environments where they intermittently experienced extended time-periods with little or no food.(30, 31) 

Anton et al. also lay out some of the biological details to back up this idea. In particular, they argue that the body is designed to work well when it will have periods of relying on the burning of body fat for energy. Since the liver’s stores of glycogen have to be run down before body fat is metabolized, making sure there are periods when the body relies on fat-burning requires a minimum number of hours of fasting or something close to fasting. Without those fat-burning periods, many things go wrong. Things go better with periodic fat-burning periods. Here is the explanation given in “Flipping the Metabolic Switch”:

… what is this metabolic switch and how is it flipped? Here, we define the metabolic switch as the body’s preferential shift from utilization of glucose from glycogenolysis to fatty acids and fatty acid-derived ketones. … Of relevance to weight management, this switch represents a shift from lipid synthesis and fat storage to mobilization of fat in the form of free fatty acids (FFAs) and fatty-acid derived ketones. …

The metabolic switch typically occurs in the third phase of fasting when glycogen stores in hepatocytes are depleted and accelerated adipose tissue lipolysis produces increased fatty acids and glycerol.(21) The metabolic switch typically occurs between 12 to 36 hours after cessation of food consumption depending on the liver glycogen content at the beginning of the fast, and on the amount of the individual’s energy expenditure/exercise during the fast. …

There is a lot of evidence that our bodies run better on average when we have substantial periods of fasting. Some of the evidence is on “Time Restricted Feeding” (TRF), which involves an eating window of no more than 12 hours a day and hence daily periods of about 12 hours with no food. Some of the evidence is on alternate-day fasting (ADF), which probably involves fasting periods of 32 hours or more. Other evidence is about modified alternate day fasting (MADF), which restricts calories to something like 500 calories on the “modified fasting” day. Anton et al. argue that the benefits of fasting are greater than the benefits of continuous calorie restriction (CR) which means eating three meals a day on a typical schedule, just less in each meal. Here are some of the benefits as Anton et al. describe them (emphasis added):

Placing time restrictions on feeding has been shown to have broad systemic effects and trigger similar biological pathways as caloric restriction.(5) For example, IF [intermittent fasting] regimens have been shown to improve cardio-metabolic risk factors (such as insulin resistance, dyslipidemia and inflammation cytokines),(13) decrease visceral fat mass,(6) and produce similar levels of weight loss as CR [continuous caloric restriction] regimens.(8) In addition to the weight loss effects and metabolic improvements, several other beneficial effects of therapeutic fasting have been described including improvements in lipid profiles,(14) osteoarthritis,(15) healing of thrombophlebitis,(15) healing of refractory dermal ulcers, (16) and tolerance of elective surgery.(17)

Some people worry that fasting will reduce lean muscle mass. But the evidence suggests that it is continuous caloric restriction that reduces lean muscle mass, not fasting:

… retention of lean mass is increased following IF regimens for weight loss as compared to continuous CR regimens in humans.(8) Additionally, in mice, the decline in muscle mass that occurs during normal aging is prevented by time restricted feeding (TRF) involving 40% caloric restriction.(23)

…

With caloric restriction, approximately one-fourth to one-third of the weight loss is known to be of lean tissue. In a study of 34 healthy men randomly assigned to either a normal control diet or daily TRF (16 hours of daily fasting) and followed for two months during which they maintained a standard resistance training program, the men in the TRF group showed a reduction in fat mass with retention of lean mass and maximal strength.(125)

Rodent Evidence

References to the emerging human evidence on fasting are sprinkled throughout this post. But some of the important evidence on the benefits of fasting is rodent evidence. In “The Case Against Sugar: Stephan Guyenet vs. Gary Taubes,” I express my doubts about the relevance of rodent evidence when arguing about lowcarb vs. lowfat diets, because rodents are probably much better adapted to a highcarb lowfat diet than humans are. (If nothing else, those rodents than hung around humans had many times as many generations to adapt to the agricultural revolution than humans did because rodent generations are a lot shorter than human generations.) However, when it comes to fasting, it seems more likely that key mechanisms are the same between human beings and rodents. The particular diet rodents are adapted to is different from humans, but the historical need to endure periods of little or no food is similar between humans and rodents. Here is a description of some of the rodent evidence (emphasis added):

Interestingly, the decline in muscle mass that occurs during normal aging in mice is prevented by 40% CR/TRF … (23) …

The decline in cognitive function with age is forestalled in mice maintained on 40% CR/TRF.(97, 98) … (99) … (97)

Recent studies of laboratory animals provide further support that cognitive function and physical performance are enhanced by IF. … (106) … (107) … (108) Thus, findings from pre-clinical trials suggest IF can improve cognitive and locomotor performance even when initiated late in life.

Numerous studies have shown ADF can protect neurons in the brain against dysfunction and degeneration in animal models of a range of different neurological disorders including epilepsy,(109) Alzheimer’s disease,(110) and Parkinson’s disease (111) and stroke (112).

Is Fasting Dangerous?

The simple answer to the question “Is fasting dangerous?” is that complications can arise with fasts of several weeks or more. Anton et al. write “The adverse events described above have only occurred during or following extended fasts of several weeks or more” (emphasis added) about the following list:

… nausea and vomiting,(47) edema,(48) alopecia and motor neuropathy,(14) hyperuricemia and urate nephropathy,(49) irregular menses,(49) abnormal liver function tests and decreased bone density,(17) thiamine deficiency and Wernicke’s encephalopathy,(50, 51) and mild metabolic acidosis.(52) Additionally, several deaths have been reported during or immediately following therapeutic fasting with the etiologies including lactic acidosis, small bowel obstruction, renal failure, and cardiac arrhythmias.(53)

In human history, there is a lot of experience with fasting. It is not a new idea:

Historically, fasting has been used as both a religious and a medical practice for thousands of years. Fasting for medical purposes has been suggested since the time of ancient Chinese, Greek and Roman physicians.(33) Throughout the millennia, many have recommended fasting for medical reasons. For example, Benjamin Franklin has been quoted as saying “The best of all medicines is resting and fasting.”(34) Similarly, Mark Twain wrote “A little starvation can really do more for the average sick man than can the best medicines and the best doctors. I do not mean a restricted diet; I mean total abstention from food for one or two days.”(35)

Experimental evidence for the benefits of fasting are bolstered by observational evidence of religiously-motivated fasting:

An emerging literature indicates IF can also ameliorate many of the key features of the metabolic syndrome in humans by decreasing fasting glucose, fasting insulin, and insulin resistance.(8, 138) …

… IF regimens ranging in duration from 8 to 24 weeks have consistently been found to decrease insulin resistance.(12, 115, 118, 119, 122, 123, 131, 132, 134, 140) In line with this, many, but not all,(7) large-scale observational studies have also shown a reduced risk of diabetes in participants following an IF eating pattern. For example, in a study conducted by Horne and colleagues,(120) a series of patients in Utah undergoing coronary artery cauterization were surveyed for the practice of periodic fasting (a common religious practice in the Mormon Church) and for the presence of diabetes based on diagnosis and medication use. Participants who reported periodically fasting had a significantly lower odds ratio for having diabetes compared to those who did not report fasting regularly.

(I used to be a Mormon, so this is relevant to my personal experience. See “"A Barycentric Autobiography.”)

What Does This Mean for You?

First, you should think of fasting as being in the same angelic category as exercise. Anton et al. write:

Accumulating evidence suggests some organ systems exhibit similar cellular and molecular responses to aerobic exercise and IF (e.g., suppression of mTOR, stimulation of autophagy, and mitochondrial biogenesis).(83, 84)

…

The effects of ADF on heart rate, blood pressure and heart rate variability are very similar to the effects of endurance training, suggesting similar underlying mechanisms.(94)

Second, don’t fall into the pattern customary for our culture of three meals a day, every day:

Individuals with a typical Western eating pattern of three or more meals per day never flip the metabolic switch and thus their ketone levels remain continuously low. Additionally, as their insulin resistance increases with excess weight and diabetes, the time it takes to flip the switch is prolonged (Figure 2). … IF [intermitten fasting] eating patterns may result in a wide range of beneficial effects on health including improved glucose metabolism,(7, 10, 114–116) reduced inflammation,(117, 118) reduced blood pressure,(12, 75, 115, 119) improved cardiovascular health,(120–123) and increased resistance of cells to stress and disease in humans (Figure 3).(118, 124)

I have a lot of posts about fasting listed in my bibliographic post “Miles Kimball on Diet and Health: A Reader's Guide.”

What Further Research is Needed?

Anton et al. call for the following additional research:

Human trials of IF that include cognitive and physical performance outcomes are unfortunately limited. Studies of cognition and mood during extended fasts, however, suggest few or no adverse effects, and improvements in performance in some cognitive domains including executive function have been reported.(142–144) In regards to physical performance, a recent randomized controlled trial of IF (20 hours of fasting 4 days/week) during one month of resistance training in men demonstrated superior improvements in upper and lower body endurance in the IF group compared to the control group.(130)

…

While our review suggests IF results in both weight and fat loss (even when caloric intake is not limited), as well as increased insulin sensitivity in overweight subjects, there remains an important need for randomized controlled trials (RCTs) of IF in normal weight subjects. Emerging findings indicate that IF when combined with resistance training can produce beneficial changes in body composition and strength in young, healthy males. Additional studies are needed to better understand the effects of combining IF with resistance training on body composition and strength outcomes in other populations.

There remains an important need for interventions that can improve unhealthy changes in body composition that occur during aging. Given the known loss of lean mass that occurs during both aging and continuous CR, IF regimens may be an effective approach to help older adults lose unhealthy weight while retaining larger amounts of lean mass.

I notice one other huge hole in the research that has been done so far. I am gradually learning more about research on diet and health. So far, it is my sense that research on what to eat (especially the lowcarb vs. lowfat debate) and research on when to eat have proceeded mostly in isolation from one another. This is too bad. If I have had one big them on this blog is that lowcarb (or really, low-insulin-index) eating (see “Forget Calorie Counting; It's the Insulin Index, Stupid”) is the key to making fasting easier.

I read the evidence so far as indicating that both lowcarb eating and frequent fasting are separately beneficial. But I’ll bet that together they are even better. We need evidence to test this idea. The concept of a metabolic switch helps explain why lowcarb eating and fasting might go together well. If you are eating highfat lowcarb, it is more similar metabolically to the body metabolizing its own fat, so there is less of a wrenching changeover during fasting. (I hasten to add that when I say highfat, lowcarb, that carbs like nonstarchy vegetables are totally exempted. By lowcarb, I only mean low in easily digestible carbs like processed food, starchy vegetables and excessive fruit.)

Conclusion

There are many areas where the lack of research angers me. Fortunately, research on fasting is coming thick and fast. The evidence is coming in so strongly, that pro-fasting attitudes are likely to begin to appear more and more in popular culture. But everyone who wants to try fasting should also try combining it with a low-insulin-index diet to see if my prediction that fasting will then be easier is borne out for them.

For annotated links to other posts on diet and health, see “Miles Kimball on Diet and Health: A Reader's Guide.”


Claudia Sahm's Offer to Give Feedback on Economics Job Market Papers →

Kudos to Claudia Sahm for offering to give feedback to economics job market candidates on their job market paper. The title of this post is a link to Claudia’s Twitter thread on this.

Note also Jericho Hill’s offer:

On Being a Copy of Someone's Mind

Robin Hanson’s book The Age of Em is a fascinating and important book applying economic theory to analyzing a dramatic technological possibility in the future: the possibility that before we truly understand the human mind and before artificial intelligence built up from first principles can match human intelligence, we might be able to make functional, faithful, software emulations of the workings of particular human brains. Robin gives these emulations the affectionate nickname “ems.”

There is much too much in The Age of Em to talk about to fit into a single blog post. Today I will address only one issue: if a copy of your own mind is made into an em, what is the experience like once that em is started up?

At one level the answer is easy. The em that is a copy of you will act just like you and say and do the same kinds of things you would say and do if you suddenly found yourself a bit of software in a virtual world but otherwise were yourself.

As I say in “On the Effability of the Ineffable,” the mysteries we talk about are not really ineffable, because we are talking about them! (Ineffable: Beyond expression; indescribable or unspeakable.) An em that is a copy of your mind will talk about things in exactly the way you do. And what the em says and does, or readings of its brain emulating activity will be the only access anyone else has to what it is like to be that em, just as what you say and so and readings of your brain activity are the only access anyone else has to what it is like to be you.

There are two obviously important cases. (I’d be glad to hear about others.) One is if dualism is true. If there is a spirit or soul inside of you that does the experiencing, then what the experience of an em is like depends on whether ems get to have a spirit or soul or not. That then depends on facts about what the gods or natural processes that grant or produce spirits or souls do.

The other obviously important case is if our experience comes from the interactions of particles and fields that are either now or someday will be known to physics, none of which individually has any more of spirit or soul than any other particle or field. In that case, it is hard to see why ems would not experience things. Since—if they are truly faithful emulations—they would speak and act as if they are experience things at exactly the same depth as human beings, it is also hard to see why they wouldn’t be experiencing things in the same way as human beings.

But is an em that is an emulation of your brain more like another human being who is eerily like you, or more like a you? On the assumption that experience comes from particles and fields known to physics (or of the same sort as those known to physics now), and that the emulation is truly faithful, there is nothing hidden. An em that is a copy of you will feel that it is a you. Of course, if you consented to the copying process, an em that is a copy of you will have that memory, which is likely to make it aware that there is now more than one of you. But that does NOT make it not-you.

You might object that the lack of physical continuity makes the em copy of you not-you. But our sense of physical continuity with our past selves is largely an illusion. There is substantial turnover in the particular particles in us. Similarity of memory—memory now being a superset of memory earlier, minus some forgetting—is the main thing that makes me think I am the same person as a particular human being earlier in time.

Noah Smith’s religion guest post “You Are Already in the Afterlife” makes this point nicely: we continue to become different than we were before, yet consider ourselves the same person. ]

Why should I consider myself the same person as the Miles Kimball twenty years ago, who in many ways was very different in characteristics, but think an em copied from me right now and started up a minute from now, who is much more similar to me, is a different person?

Just as important, if I seem to have a continuity of conscious experience despite the fact that the particles making me up keep changing, there is no reason to deny that there is a continuity of conscious experience from me to the em that is a copy of me. The weird thing is that with such copying, there would be several different continuities of conscious experience. One line of conscious experience that ended up outside any computer and another line of conscious experience that ended up inside a computer. (Note that distance in time is not a big issue: we are used to what counts as a “continuity of consciousness” having a sleep state intervening. Being in “suspended animation” as a recorded computer state is less of an interruption than a sleep period, because a sleep period changes the state more.)

In the technological environment Robin and I are considering, after the copying event these two lines of conscious experience are isolated from one another as any two human beings are mentally isolated from one another. But these two consciousnesses that don’t have the same experience after the split are both me, with a full experience of continuity of consciousness from the past me. If one of these consciousnesses ends permanently, then one me ends but the other me continues. It is possible to both die and not die.

The fact that there can be many lines of subjectively continuous consciousness that are all me may seem strange, but it may be happening all the time anyway given the implication of quantum equations taken at face value that all kinds of quantum possibilities all happen. (This is the “Many-Worlds Interpretation of Quantum Mechanics.”) Indeed, although one type of splitting originates in macroscopic events and the other type of splitting originates in picoscopic events or smaller, they have the same qualitative description as things that have all the same observable consequences of real splitting with all paths continuing, even if one wants to deny that it is real splitting with all paths continuing. There is complete observational equivalence.

Note that, along the lines of what I said in “On the Effability of the Ineffable,” if there is any way I can even think to myself something ineffable, that is enough brain activity that it could, in principle, be revealed to someone else. So—short of hardcore dualism with a spirit or soul—it is hard to see what distinctive magic there could be to the “true me” to distinguish it as me and the copy of me as not-me. Is being composed largely of water really the magic that makes it the real me?

And my problem with hardcore dualism is this:

  1. If a spirit or soul influences any of my decisions, then it has enough effect on particles in the brain that it should be detectable by physics with the sensitivity of instruments we have now.

  2. If a spirit or soul is affected by the body but does not itself have any effect on the body (Epiphenomenalism), then it is not through any causality from that spirit or soul the spirit or soul that we talk about because it has no causal pathway to move our mouths. God might make our bodies so they talk about our epiphenominal spirits or souls. But our spirits or souls in this case are not talking about themselves on their own behalf.

Conclusion. The bottom line is that I think an emulation of my brain would have a genuine continuity of consciousness with me as me. There would be a weirdness of there being more than one of me, or one me that ends and another me that continues, but that would be “just the way it is.”

Don’t miss these related posts:

Reza Moghadam Flags 'Enabling Deep Negative Rates to Fight Recessions' in the Financial Times

I announced Ruchir Agarwal’s and my new IMF Working Paper in “Ruchir Agarwal and Miles Kimball—Enabling Deep Negative Rates to Fight Recessions: A Guide.” We are both delighted to see Reza Moghadam flag it in a Financial Times op-ed: “The ECB must make negative interest rate policy effective.”

Below, I quote the key passage from Reza’s op-ed, with my own section headings interspersed—headings that reflect what Ruchir and I call the various issues. After that, I repeat some Twitter exchanges I have had, prompted by Reza’s op-ed; these Twitter exchanges illustrate what Ruchir and I call “the political problem” and some of the ways Ruchir and I see for partially addressing the political problem. Here is Reza:


The Bank Profits Problem and the Paper Currency Problem

… with the ECB deposit rate already minus 0.4 per cent, the scope for meaningful cuts in interest rates seems limited. This credibility problem with interest rate policy requires the ECB to overcome two obstacles.

First, as it is, banks are not fully passing on the negative rate they pay on reserves at the ECB. Of course, banks can still make profits so long as their lending rates are above their borrowing costs. But while they have passed on negative rates to corporate depositors, they have not done so to households. No bank wants to undermine its funding base or be the first mover. Other things being equal, the result is lower bank profitability or higher lending rates, which weakens policy effectiveness.

Second, even if the above issue were resolved, there remains the risk of a flight to cash: as currency guarantees a zero rate of return, significantly negative deposit rates risk a large shift from deposits to cash — thus destabilising banking and economic activity.

If the ECB is to make negative rate policy truly effective, it will need to come to grips with both the transmission problem and the flight-to-cash problem. Fortunately, there are solutions, as recently discussed in an IMF paper by the economists Ruchir Agarwal and Miles Kimball.

Addressing the Bank Profits Problem

On the transmission problem, the ECB could shield small depositors from negative rates. For example, the ECB could ensure that, say, the first €5,000 of each depositor’s account is guaranteed a minimum deposit rate of zero.

The cost of such a subsidy, which ECB data suggest would fully compensate the bottom two-thirds of households by income, would be around €15bn for each percentage point of negative rates.

This seems manageable relative to the ECB’s profits and, more importantly, the goal of transmitting monetary policy to the broader economy. Such a policy can make negative rates more politically acceptable by protecting regular households, while limiting the negative impact on bank profitability. This would also be preferable to recent proposals for “tiered” ECB rates, which benefit a narrow group of banks.

Addressing the Paper Currency Problem

On the flight-to-cash risk, cash holding can be made costly. Specifically, the ECB could impose a transaction fee — equivalent to a negative interest rate — whenever a bank approaches it to obtain currency. Banks routinely turn to the ECB for currency when customers make unexpectedly large cash withdrawals at a branch or an ATM. Citing the fee, banks should be able to pass the cost on to the public. By varying the fee at its cash window, the ECB can operate the system at any negative rate it chooses.

The Political Problem

None of this is to play down the logistical and communications challenge in moving to deeply negative interest rates …

Andreas Michalsen on Fasting

Andreas Michalsen has a new book: The Nature Cure: A Doctor’s Guide to the Science of Natural Medicine.

Link to the Amazon page for The Nature Cure

Link to the Amazon page for The Nature Cure

His August 1, 2019 Wall Street Journal op-ed “The Fasting Cure Is No Fad” is, I assume, a teaser for his book. And that teaser for his book is all about fasting.

In addition to weight-loss, as a doctor, Andreas uses fasting to help his patients with “diabetes, high blood pressure, rheumatism and bowel diseases, as well as pain syndromes such as migraines and osteoarthritis.” He typically tells his patients to restrict themselves to no more than a ten-hour eating window each day. (In “Miles Kimball on Diet and Health: A Reader's Guide” I have links to many blog posts about fasting. I also recommend Jason Fung and Jimmy Moore’s book “The Complete Guide to Fasting.”)

Andreas lists many positive effects of fasting. Let me give a theory about how they all hang together. I’ll bet that in the environment of evolutionary adaptation our ancestors lived in before the advent of agriculture, involuntary fasting—that is, periods of time with little or no food—were quite common. As a result, many of our bodies’ systems were designed in a way that took as given that there would be frequent periods of little or no food. When people eat all the time, these systems don’t work very well.

As an analogy, think of how much the design of typical kitchen tools depends on the assumption that there will be gravity. A regular cutting board or a typical mixer wouldn’t work so well on the International Space Station! For most of our activities we take gravity for granted. And, for the most part, evolution could and often did take the existence of frequent periods of little or no food for granted—for us as well as for many other animals.

Here are some body systems that seem to work better with fasting. In the indented passages that follow, my labels are in bold; reference to relevant blog posts are in italics; the remainder of the words are Andreas’s.

For annotated links to other posts on diet and health, see “Miles Kimball on Diet and Health: A Reader's Guide.”