I've put some brain time into this one since my last posts here. At this point, here's what I think is going on. Forgive me if some of this overlaps with Seth's book--I found what's now called SLD from the original NYT article and haven't read the book.
1) The ability to discern poisonous or rotten foods from beneficial ones was extraordinarily crucial to our ancestors from an evolutionary standpoint. How else to survive all those millennia without television commercials to tell them what tasted good? As a result, they developed loads and loads of taste buds to the job--10,000 or so. And a highly developed sense of smell which, as an adjunct to those taste buds, served (serves) the same purpose.
2) Thanks to those same ancestors, our bodies understand the properties of food--recognize That Which Is Food--and are devestatingly efficient at using it for whatever purpose they may need it today--activity, recovery, hibernation, recuperation, etc.
3) Those ancestors handed down digestive system that developed hundreds of thousands of years before Ray Kroc made crappy hamburgers and owned a perennially bad baseball team. Hundreds of thousands of years before, even, we first began planting and eating grains, which is its own interesting side story.
Take 1, 2, and 3 together, and here's what I think is happening: That which has calories and no taste--that is, a substance that subverts the massive flavor-detection complex operating in our mouths, short-circuits our inherent biological and physiological expectations, is, quite simply, That Which Is Not Food.
When our body ingests That Which Is Not Food, bells ring, sirens wail, and our internal Terrorist Alert System goes to red. Nothing good can be happening outside if we're eating That Which Is Not Food. It could A) be poison, or B) be that no real food is available. Both meant death to our predecessors who got it wrong.
So just in case That Which Is Not Food is poison or famine, we shut down, go to our reserves, and lie low. The last thing we want is to eat more of whatever that was.
We close the borders. Result: appetite suppression.
When we're ready to venture out again, we go very slowly. We look for those "safe" foods that signal most directly That Which Is Food. Fruits, vegetables, meats. Whole foods, nothing processed. (Processed food, to our caveman body, is essentially another dose of That Which Is Not Food.)
Here a distinction needs to be made between eating That Which Is Not Food intentionally--as in a famine--and by mistake, as in a poisonous flower.
In a famine, we'll continue to eat That Which Is Not Food. Our set point may kick in, if it's real, and we'll assume it's essentially winter. Hunker down and hibernate.
But--and this is important, to me--that doesn't happen with SLD. SLD is the other kind of TWINF--the one eaten by mistake. Poison. Later today (a meaningless span of time, in bodies perfected during less plentiful times), we will find and eat That Which Is Food. We may start slowly at first, but we'll eventually become convinced that there is That Which Is Food around, our appetite will begin to return, and as more real food enters our system, we will grow more and more comfortable that we may now eat as we please.
Until we take another dose of That Which Is Not Food and it all starts again.
On SLD, we stop eating because This Way Danger Lies. Sure, we go to Plan B, which is to use up our fat stores. But I don't think it's because we're flipping any kind of switch so soon. I think it's because we're sending our bodies under the bed with duct tape on the windows for so many hours a day that it simply can't take in enough calories to avoid gaining weight. Eat few enough calories, you will lose weight. Eat shag carpet and the results will be pretty much the same.
Now, having said all that, I think even that is perhaps 70 percent of the story, at best. I think--know--we eat like we do out of habit and convenience. Certainly it's not out of need, since our systems could care less about our Fast Food Nation. They developed with very different needs and available food sources and habits.
So I think that once we begin developing a new habit--not eating like fat dumdums--we greatly augment the hiding-under-the-bed effect with our own brainy additions. Like, "Now that I know I'm able to say no to potato chips, I think I'll pass." 70 percent Code Red, 30 percent behavior modification.
Add to that the cascading effect of enjoying your new body and well-being, and I think the percentage shifts over time--to perhaps, oh, 40 percent Intruder Alert, 60 percent "Hey, I'm looking pretty good, how do I keep THIS going?" So we add in an extra gym day, skip an extra glass of juice, etc, and suddenly we've taken over our own weight loss from the Department of Homeland Security.
That's my take. Set point uses the same mechanisms--fat storage and consumption--but does not account for all or even most of the physiological responses to eating That Which Is Not FoodTM by mistake.
Speaking of benefits: 12 pounds in nine weeks. No wonder they keep raising that damned terror alert down in Washington DC.