Seth’s blog

The discovery of flavor-calorie learning (in rats) was no surprise. It was another example of flavor-consequence learning, which was well established. In the 1950s, John Garcia had found that if you make a rat sick after exposing it to a new flavor, it will avoid that flavor. Flavor-consequence learning belongs to the larger category of Pavlovian learning (also called classical conditioning), the sort of learning where an animal learns that an unimportant event (such as a bell) predicts an important event (such as food). Pavlovian learning belongs to the larger category of associative learning, which also includes action-event learning, such as a rat learning that bar presses produce food pellets. The action is pressing the bar; the event is getting a food pellet.

My Ph.D. was in the field of animal learning. Almost all animal learning research is about associative learning. When I taught introductory psychology, however, I found it hard to take advantage of my expertise because most of the research had little real-world relevance. The big exception was Shepard Siegel’s work on drug tolerance and craving. Tolerance and craving are due to Pavlovian learning, Siegel argued. Flavor-calorie learning, happening at every meal, might have been another exception had anything interesting been known about it — but nothing was.

The usual terminology is to say that in a Pavlovian-learning experiment, the animal learns to associate the CS (conditioned stimulus, such as a bell) with the US (unconditioned stimulus, such as food). In flavor-calorie learning experiments, the flavor source is the CS, the calorie source the US.

In a series of posts, each titled Calorie Learning: [something], I’m going to use a blog to communicate self-experimentation. To see the whole series, look in the category Calorie Learning (under Self-Experimentation).

This research will be about how we (or at least I) learn to associate flavors with calories — more precisely, smells with calories. This learning is at the heart of the Shangri-La Diet, which derives from a theory that says the flavors of your food increase your set point if they are associated with calories. The stronger the association, the bigger the increase.

Why study this? 1. Maybe I can improve the diet. 2. It matters. It happens with every bit of food you eat. It controls what you eat and your appearance (assuming my theory is right). 3. Little is known about it. As I wrote in the appendix to The Shangri-La Diet, Anthony Sclafani has studied this learning extensively in rats. No one has studied it extensively in people. 4. The experiments can be simple and easy — or at least that’s what I think now.

A few weeks ago, a friend told me how much she liked those cellophane-wrapped white-bread sandwiches sold in delis and bodegas. Egg salad sandwiches, for example. They were addictive, she said. That sounded about right: White bread (and bread in general) is digested very fast, witness its very high glycemic index. Fast digestion means the calorie signal it generates in the brain overlaps a great deal with the flavor signal it generates in the brain. The more overlap of the two signals, the stronger the association created. The stronger a flavor’s association with calories, the more you like it.

Her comment gave me an idea: I can create a random new flavor by randomly combining many spices, mixing them into butter, and spreading the butter on white bread. The spices supply the flavor, which I can reproduce as often as I want by making a big enough batch of spicy butter when I start. Spice mixtures are cheap. I can easily and cheaply make a huge number of flavors that should taste entirely new. This means I can start fresh — which is where you want to start when doing a learning experiment — as often as I want. White bread is cheap, easily available, has little flavor, and provides a strong signal per calorie. If I want to increase the time between the flavor and the calories, maybe I can spread the butter on crackers, which have few calories, and eat the bread later.

Will it work? Stay tuned.

At the heart of the Shangri-La Diet is the idea that we learn to associate flavors (smells) with calories. This learning was first shown in rat experiments. There’s some human evidence, but not much. If I could discover more about what controls this learning, I might be able to improve the diet. For example, maybe I could say more about what the flavor-free window should be.

My earlier self-experimentation on this subject - I used tea for flavor and sugar for calories — was helpful. To my surprise, I found that really small changes in flavor made a noticeable difference. If I switched from one canister of Peet’s Gunpowder Tea to a new canister, the ratings went down, although everything else stayed the same. From this came the notion of ditto food: Foods with exactly the same flavor each time are especially fattening. I hadn’t realized what a difference it would make if you kept the flavor exactly the same each time.

It’s been hard to learn more. After Christmas dinner, my mom gave me the leftover brandy (A. R. Murrow). I used it for a very simple experiment in which I learned to like it. I’ve never drunk brandy in any quantity and I started off not liking it. Every day for a few weeks, I drank one tablespoon. I drank it in a few sips over a few minutes. I didn’t eat anything else for at least 30 minutes. I rated how good it tasted on a 0-100 scale where 10 = very bad, 20= quite bad, 25 = bad, 30 = somewhat bad, 40 = slightly bad, 50 = neutral, 60 = slightly good, 70 = somewhat good, 75 = good, 80 = quite good, 90 = very good. The overall rating was the maximum of the ratings of the several sips. (The first sip usually tasted the best.)

Here are the results.

I’ve observed similar results five or six times. They are more support for the most basic conclusions: 1. The effect is very clear. One tablespoon of brandy has only 30 calories. 2. A really simple experiment is easy.

That’s a promising start but then it gets hard, or at least non-obvious. As a way to study flavor-calorie learning, this little example has several flaws: 1. Slow learning. 2. Expensive materials. 3. Little control of flavor. The best I can do is choose which liquor to buy. Soon I will run out of ones I haven’t used. 4. No way to separate flavor and calories in time. 5. No way to change the calorie source.

An earlier demonstration used a soft drink. It’s really Science in Inaction: I’ve made zero progress in a year.

The Shangri-La Diet is partly based on the idea that we learn to associate flavors and calories. A food’s flavors become associated with the calories in the food. This association makes the flavor more pleasant.

I would like to learn more about this associative process so I have been studying it. Here is a simple example. At intervals of a day or so between bottles, I drank 4 bottles of a lemongrass-flavored soda. I chose that flavor because it was unfamiliar. Each bottle had 50 calories of cane sugar. I rated how pleasant each bottle tasted on a scale where 40 = slightly unpleasant, 50 = neutral, 60 = slightly pleasant, and 70 = somewhat pleasant. I drank the bottles between meals — far away from other food.

Here are the ratings.

The flavor gradually became more pleasant.