Isegoria

Seth Roberts’ What Makes Food Fattening? is fascinating:

The theory takes a familiar idea — body fat is regulated by a system with a set point — and adds two rules about how the set point changes. One rule is that calorie-associated flavors raise the set point — the stronger the association, the greater the increase. The other rule is that these increases are superimposed on a steady decline — the greater the set point, the faster the decline. A steady state is reached when the rate of flavor-generated increases equals the rate of decline. A food is fattening (raises the set point) to the extent its flavor is associated with calories. The strongest flavor-calorie associations will occur, learning research implies, when four things are true: (a) the flavor is strong and complex flavor; (b) the food is digested quickly; (c) the food is eaten repeatedly; and (d) the flavor is exactly the same from one instance to the next. These four traits combine in a multiplicative way in the sense that if one is entirely absent, the food will not raise the set point at all.

His advice:

The theory supports the common recommendation to avoid foods with a high glycemic index (e.g., Atkins, 1992; Montignac, 1999; Steward, Bethea, Andrews & Balart,1995) but also provides some unusual advice:

1. Eat new foods. No food with a new flavor is fattening, the theory implies.
2. Vary the flavor of foods eaten repeatedly. If products came with optional flavoring packets and consumers added varying amounts of the flavorings, this would produce variation in flavor. The results of Hirsch and Gallant-Sheen (2004) suggest the power of this advice.
3. Consume calories with no flavor associations. Ingestion of calories with no flavor should lower the set point, the theory implies. The fructose-water results suggest that ingestion of a small fraction of one’s daily calorie intake this way may substantially reduce the set point.

Flavorless vegetable oils (vegetable oils, such as olive oil, from which all flavor molecules have been removed) are a possible source of calories without taste.

The latest Freakonomics column, Does the Truth Lie Within?, looks at Seth Roberts and his self-experimentation:

Over the years, he had tried a sushi diet, a tubular-pasta diet, a five-liters-of-water-a-day diet and various others. They all proved ineffective or too hard or too boring to sustain. He had by now come to embrace the theory that our bodies are regulated by a “set point,” a sort of Stone Age thermostat that sets an optimal weight for each person. This thermostat, however, works the opposite of the one in your home. When your home gets cold, the thermostat turns on the furnace. But according to Roberts’s interpretation of the set-point theory, when food is scarcer, you become less hungry; and you get hungrier when there’s a lot of food around.

This may sound backward, like telling your home’s furnace to run only in the summer. But there is a key difference between home heat and calories: while there is no good way to store the warm air in your home for the next winter, there is a way to store today’s calories for future use. It’s called fat. In this regard, fat is like money: you can earn it today, put it in the bank and withdraw it later when needed.

During an era of scarcity — an era when the next meal depended on a successful hunt, not a successful phone call to Hunan Garden — this set-point system was vital. It allowed you to spend down your fat savings when food was scarce and make deposits when food was plentiful. Roberts was convinced that this system was accompanied by a powerful signaling mechanism: whenever you ate a food that was flavorful (which correlated with a time of abundance) and familiar (which indicated that you had eaten this food before and benefited from it), your body demanded that you bank as many of those calories as possible.

How did he act on this theory?

So Roberts tried to game this Stone Age system. What if he could keep his thermostat low by sending fewer flavor signals? One obvious solution was a bland diet, but that didn’t interest Roberts. (He is, in fact, a serious foodie.) After a great deal of experimenting, he discovered two agents capable of tricking the set-point system. A few tablespoons of unflavored oil (he used canola or extra light olive oil), swallowed a few times a day between mealtimes, gave his body some calories but didn’t trip the signal to stock up on more. Several ounces of sugar water (he used granulated fructose, which has a lower glycemic index than table sugar) produced the same effect. (Sweetness does not seem to act as a “flavor” in the body’s caloric-signaling system.)

The results were astounding. Roberts lost 40 pounds and never gained it back. He could eat pretty much whenever and whatever he wanted, but he was far less hungry than he had ever been. Friends and colleagues tried his diet, usually with similar results. His regimen seems to satisfy a set of requirements that many commercial diets do not: it was easy, built on a scientific theory and, most important, it did not leave Roberts hungry.