Wow!† A lot of great questions and suggestions.† †Let me try to respond:
1.† Regarding tests of my theory, I too have thought how nice it would be to have a blood insulin meter I could use to check my levels before and after various dietary experiments.† Alas, to my knowledge, these are not yet available to consumers, as are the ubiquitous blood glucose meters that diabetics routinely use.† †I have read some articles on some devices that are now in development, but probably still years away from being in drugstores.† †Unfortunately, one cannot use blood glucose measurements to calculate or make any reliable inferences about insulin levels -- the two are independent measurements at any given moment in time, since blood sugar depends not only on insulin level, but also whether one has recently eaten, fasted, or excercised.
On the other hand, there are plenty of "tests" of my theory in the medical and scientific literature, where insulin levels of humans and animals have been extensively measured in response to various feeding protocols, including foods with different macronutrient compositions, flavors, frequencies, etc.† †The article I cited by Karen Teff in Reply #27 is but one example.† I'd like to encourage anyone reading this to see what they can find to confirm or refute my proposals here.
2.† Hedi555 asks how a small amount of oil taken one day could suppress appetite into the following day.† I don't really know for sure.† But I suspect it is due primarily to the fact that it is not just the small amount of oil, but also the time window before and after the oil that strongly suppresses insulin levels.† It takes time for insulin levels to come down after they are high.† It is well known that a high fat meal (which would include pure oil) suppresses insulin and allows free fatty acid levels to remain high in the bloodstream, signaling satiety.† But the fats must be consumed in the absence of glucose, which is why you have to wait a few hours before taking the oil.† †And the oil further reduces circulating insulin to a trace level.† Furthermore, low insulin will allow additional fatty acids to be released from the adipose tissue, and continuously burned as a fuel -- so satiety will be maintained for hours and hours...maybe days!† † At that point, eating further meals will be done in the context of there already being a lot of fuel in the bloodstream, so the satiety signal will come soon, particularly if the meal is not too large or rich in carbohydrates (or to a lesser extent, high in protein, which also induces insulin).† †Continued high fat meals or flavorless oils will continue to suppress appetite.† In fact, besides the SLD, the most effective weight loss method I've found is a high fat diet, with low carbs, but also relatively low protein.† †This really leads to great appetite suppression and easy weight loss.† And, after reading the first half of Taubes, I'm more and more convinced it is safe and healthy, even using some saturated fats.† (Salads with a few nuts and goat cheese are great!).
3.† Regarding how sugar water suppresses appetite, I'm inclined to agree with BJane that, a small amount of sucrose without a flavor signal will avoid any preprandial secretion of insulin, and the insulin secreted will be a relatively small amount, such that glucose will remain in the bloodstream and signal satiety.† Again, this will only work if the insulin levels beforehand were low, which is a reason for waiting 2 hours before and after.† †So you are targeting a narrow window of sugar concentration -- high enough to provide satiety, but not so high as to raise insulin and cause the glucose to be shunted out of the bloodstream and into the liver to produce triglycerides.† My prediction is that increasing the amount of sugar to a much higher level will defeat this mechanism and you will actually get hungry once the insulin response kicks in and draws glucose out of the bloodstream.† Whereas, I believe that taking excess oil will only suppress appetite further.† †I'm not a sugar user and it didn't work for me -- so is there anyone out there who uses sugar who is willing try taking an excess of sugar to see if this prevents appetite suppression?† Or try very high oil levels and see how full you become.† (Try for example my oil milk recipe in the tips section, or if you are brave try a real treat --† a "cream soda" -- pour some heavy whipping cream over a few ice cubes and fill the glass to the top with bubbly mineral water.† No sugar, please!).
By the way, other than the explanation of "insulin quieting", is there any other explanation for Seth's window of 1-2 hours before and after taking the flavorless calories?† Seth explains the SLD as being based a learned dissociation between flavor and calories, but it seems to me rather odd that we can only learn to dissociate flavors from calories if they are separated in time by 1-2 hours, yet not 10-15 minutes.† †I don't know other cases of associational learning that have such strict limits on the time between presentations of the two items being associated.† Whereas the insulin hypothesis is based on very well established evidence of the rate at which insulin levels decline in most individuals.† (And may explain why in diabetics or obese individuals, one may have to adjust the timing of the SLD doses).
4.† Fructose should have less tendency to induce insulin than sucrose, at least initially.† But I've read research suggesting that ultimately it induces other physiological changes that lead to higher insulin levels, and even more rapid conversion to triglycerides than sucrose or other sugars.† I'm less sure about how fructose works.
5.† Several of you (m.c., Indiangirl) commented on a blood sugar crash or weakness shortly after taking the oil or the sugar.† † I can understand the effect with sugar for folks who have a high starting insulin level, because the sugar will further spike insulin and cause a blood sugar crash.† †In that case, I would suggest waiting longer before taking the sugar and cutting down the dose of sugar.† If that still causes a problem, it suggests you are very sensitive to insulin.† (A Glucose Tolerance Test by your doctor would confirm that).† †The blood sugar crash from the oil is harder to explain.† All I can think of is that, again, you need to wait longer after a meal, especially a high carbohydrate or sugary meal, so that you are not still digesting carbohydrates and so your insulin level is low.† How about trying it first thing in the morning, and maybe taking a large dose of oil, to be sure you get fuel into your bloodstream, while keeping insulin levels low?
6.† Regarding unusual spices or flavors, I tend to agree with BJane that these do not activate the vagal nerve or Pavlovian response to flavors, and hence preprandial insulin is avoided or minimized in the same manner as flavorless calories, thereby allowing stealth calories in a fashion that keeps insulin levels low.
7.† Kirk, that was a very intriguing thread you pointed me to on "How Does the Body Know Its Weight?"† In that thread, Seth Roberts proposes leptin as the biochemical agent that underlies the body weight setpoint, and answers the question as follows:†
It uses the concentration of leptin in the blood. Fat cells produce leptin--the more fat, the more leptin. The blood gathers the leptin from all the fat cells and carries it to the brain. The brain detects the concentration of leptin in the blood and uses it to judge how much fat is on the body. What is really regulated is not body fat but leptin concentration. Which is very closely correlated with body fat.
The diet works by reducing the signal against which the leptin concentration is compared. So it takes a lower leptin concentration to feel full.
But if you read closely, notice that Seth does not propose that leptin concentration is itself the setpoint.† Rather, he proposes that leptin is the signal which is compared to the setpoint, just like the temperature is the signal which is measured against a thermostat setpoint.† But this begs the question -- where and how is this setpoint level stored, and by what mechanism does the SLD diet change it? How do we get from oil or sugar to changing a physical setting within the hypothalmus or other part of the brain?† So Seth has not really has not answered the question of the physical reality of the setpoint.
Furthermore, I do not think that leptin has proven to be an adequate explanation for how hunger and satiety work.† A lot of the initial excitement over leptin came from the fact that very low leptin levels (and elevated ghrelin levels) are associated with hunger and appetite.† But the converse has not proven true -- elevated levels do not always indicate satiety.† In fact in obese individuals, the leptin signal seems not to work very well, due to leptin resistance, which is far more prevalent than even insulin resistance.† †I think that Taubes gives a far simpler and more satisfying account of hunger and satiety, directly in terms of the availability of fuel (glucose, fatty acids or ketone bodies) in the bloodstream, which most typically results when insulin levels are elevated and have depleted the bloodstream of these fuels by driving them into the tissues.† Leptin and other hormones are induced secondarily in response to insulin, which is really the driving hormone for fuel storage and mobilization.