Stuart King writes:
I was very hungry today at dinner and the thought of sweet food wasn’t appealing at all, but after filling up on some rice, chicken and coconut cream curry I immediately had ice cream and chocolate slice [= what Americans call a brownie], which had had no appeal 15 minutes or so before!
An everyday observation that anyone can make. Studies have shown what Stuart noticed: When you are hungry sweet foods are unappealing. This is why dessert is eaten after the rest of the meal.
The main way that psychologists explain an experimental effect — choose between explanations — is by finding out what makes the effect larger or smaller. For example, discovery of what makes learning more or less (what increases or decreases the effect of one learning trial) is the main way psychologists have chosen among different theories of learning. Different theories predict different interactions.
Why do we like sweet foods? The usual answers are that sweet foods are a “good source of energy” and they provide “quick energy”. But these explanations do nothing to explain what Stuart noticed. If sugar is a good (= better than average) source of energy, we should eat it before other foods (average sources of energy) when we are hungry (hunger signals lack of energy). The opposite is true. You may not want to call it a “contradiction” but there is no doubt the conventional view does not explain what Stuart noticed. Of course many nutrition experts, such as Weston Price, are/were entirely sure sugar is unhealthy.
As a tool for choosing among theories, Stuart’s observation is especially good because (a) it is very large (sweets go from unappealing to appealing) and (b) paradoxical (eating calories should make all calorie sources less appealing).
If you have been reading this blog, you know I explain Stuart’s observation by assuming that we need sugar in the evening to sleep well. Sugar (sucrose, fructose, glucose) eaten in the evening increases blood glucose, which increases glycogen. During sleep, glycogen becomes glucose, which the brain needs to work properly. Evolution shaped us to like sweet foods after a meal so that we will eat them closer to when we sleep. (The value of replenishing glycogen close to bedtime also explains why we eat sweet foods after dinner more than after breakfast or lunch.)
I can’t think of another case where what experts say is so out of line with what’s easily observed. For example, I’m sure cholesterol doesn’t cause heart disease, but there is no everyday observation that supports my belief.
I can’t think of another case where what experts say is so out of line with what’s easily observed. For example, I’m sure cholesterol doesn’t cause heart disease, but there is no everyday observation that supports my belief.
If sugar is helpful for sleep, why is it associated with diabetes? My guess is that sugar is almost always consumed in foods that taste exactly the same each time — what in The Shangri-La Diet I called ditto foods. For example, soft drinks. Ditto foods with sugar, because they have a strong precise CS (smell) and a strong fast US (calorie signal), produce an especially strong smell-calorie association. Such an association raises the body fat set point, thus causing obesity. Obesity causes diabetes. It’s also possible that eating sugar during the day — at the wrong time — hurts sleep. Maybe sugar during the day raises insulin and thus reduces the conversion of sugar to glycogen. Less glycogen causes bad sleep, bad sleep causes diabetes. My blood sugar levels clearly improved when I started eating sweets in the evening — opposite to what the sugar-diabetes link would predict.
1. i think we crave sweets after meals because we didn’t get sugar during the meal, not because we naturally prefer it after a meal. In other words, if you have steak and potatoes, you may crave dessert. If you have a Morrocan meal with meat, rice, figs and honey, you may not crave sweets after a meal. (This would be easy to test).
2. No one craves just sugar. They want dessert, which is fat, starch and sugar together, so i see sugar as part of a balanced diet.
3. Almost all starches and meats are more palatable when eaten with sugar. Breakfast cereals are loaded with added suga;, meats like barbaque are covered in sugary sauces. I mean is there anyone when hungry who likes plain oatmeal??? No, we love it with brown sugar and fruit or honey.
4. There is a lot of discussions of what Paleo ancestors ate. First, I’ve been following the Paleo diet for over 10 yrs and it changes every few years. It was high protein and veggies, then they added more saturated fats, then they added more tubers like sweet potatoes. For a diet that hasn’t changed in a million years, it changes about every 2 yrs with a new recommendation of how we misunderstood something.
5. Which brings me to #5, Paleo people say we would not have had access to sugar but traditional peoples have collected honey throughout history. Honey can be stored indefinitely, so i kind of roll my eyes when a Paleo advocate says that we should only eat honey if you’ve gone through the trouble to climb a rope ladder, beat off beats, recover the honey and sprint away from the bees. Those same people never say you can only eat meat if you have run for miles, tracked an animal, killed it, skinned it, and carried it back to your tribe. My point is just that i think we have to be careful creating narratives for why we should or should not do something.
6. Finally, we don’t live a Paleo life. We struggle under a 10 hour cognitively demanding job with more chronic stress which has been shown to damage the brain, given sugars role in providing energy for the brain (mostly through the liver), its makes sense that we might crave (and therefore need) more sugar than we had during Paleo times.
Strauss, i agree with your points, and its a reason why i think there is confusion on the issue. Fructose is incorrectly seen as bad, but its really the refined sugars and their lack of nutrients that cause problems. Honey and fruit have a ton of nutrients that accompany the sugars and help them metabolize. Second, the glucose and fructose are free and not bound together like in sucrose.
Third, i agree that the primariy benefit of sugar is supporting the brain. With only ~2% of body mass and yet consuming 20% of the calories, keeping the brain healthy with a steady supply of fuel seems paramount.
“Seth: The research showed people liked sweets much less when they were hungry. I was trying to convey it was a big effect. I see I misled you.”
Fair enough, Seth. I still think you’re ignoring lots of readily available evidence. You’ve ignored the point about breakfast, which as the name implies is breaking a long fast, being the most commonly eaten sweet meal. That alone poses a serious challenge to your theory. That the ONE meal eaten after a long fast every day in all cultures around the world tends to be sweet, or is often sweet, and that this isn’t the case with lunch or dinner, massively does not support your theory.
There there is the well known fact that heavy dieters almost always binge on sweet foods – they don’t binge on steak and bacon and eggs, but donuts and ice cream and chocolate. Again, massive un-evidence.
Sorry, it’s a nice theory but it just doesn’t add up. Do the right thing and move on. Truth is more important than our pet theories.
Seth: You might want to read the research I mentioned, by Elizabeth Capaldi.
David, I’m quoting this because I like it:
“4. There is a lot of discussions of what Paleo ancestors ate. First, I’ve been following the Paleo diet for over 10 yrs and it changes every few years. It was high protein and veggies, then they added more saturated fats, then they added more tubers like sweet potatoes. For a diet that hasn’t changed in a million years, it changes about every 2 yrs with a new recommendation of how we misunderstood something.”
As for the rest, honey is easy to store, but I don’t have a feeling for when people invented a way (ceramics?) to store it. Could they have used animal bladders? If so, I don’t think there’d be a fossil record.
It’s true that people don’t want straight sugar for dessert. Hard candy is for snacks, not dessert. Still, dessert varies a lot in it’ fat/starch/protein/sugar ratio. Your basic cake is sugar/refined flour/a little egg and dairy. Cheese cake is mostly cheese and sugar. Let to themselves (no theory about nutrition), people don’t use whole grains in dessert so far as I know.
I believe we need more investigation of dessert.
I have been experiementing with a ketogenic diet. Recently my blood sugars upon rising have increased to well over 100. Within a couple of hours upon rising my blood sugars drop to 90. That was not the case before I started the diet,
continuing…
as my blood sugars were normally around 90 upon rising. I have been reading about the Somogyi Effect and Dawn Phenomenon for diabetics as a possible clue to why my bs have shifted. I am beginning to think the SE and DE are not mutually exculusive to active diabetics. From this post, and the one about honey before bed, I am wondering if being in a state of nutritional ketosis might just only be beneficial during the day. This thought comes about because last night I just went crazy with eating sugar before bed, and I awoke in very good spirits after having a wonderful dream. For the last several months this has not been the case. I usually had very uncomfortable dreams. I think for me my hours of rest have increased to 8 hours due to the time change. During the winter I usually will awake at 3am and stay awake for a couple of hours.
Today I am going to experiment with eating a ketosis diet through out the day and tonight I am going to have honey.
“I am beginning to think the SE and DE are not mutually exclusive to active diabetics.”
I agree. I found this in Wikipedia:
“Clinical studies indicate that a high fasting glucose in the morning is more likely because the insulin given on the previous evening fails to last long enough.”
I had/have a high fasting glucose in the morning but don’t take insulin (and am not diabetic).
So the explanation of the high glucose in the morning, at least in my case, cannot be my insulin didn’t last long enough.
I tried the honey last night, and it did not work. I actually awoke at 12am in a panic. This also happens when I have fruit. I am thinking the fructose in both is the culprit.
If bedtime honey causes you to wake up too early, try a smaller dose.
Humans are born loving sweet, fatty and salty foods. Scientists think it is evolutionary because we didn’t get much of this stuff when we first evolved so people who ate this whenever they found it lived longer and passed on liking this in their genes to their offspring. The human brain takes a lot of energy to keep it going, as well as our body, and snacking on a few plants just won’t do. Humans who ate sweet things (fruits, etc.) and fats (meats, nuts) got more nutrition and lived longer.
This does not explain why we eat sweet foods separately (dessert) and after the main food.