If our body’s “preferred fuel” is fat or ketones (at least for major organs like the brain and heart), and we use mostly fat for lower level activity (which historically has comprised the bulk of our physical movements), then why do we get crazed and hungry when we taste foods containing carbs? Wouldn’t it make more sense to seek fat based foods and have strong hunger and pleasure responses to those? I understand we have limited stores for glycogen but to me that would mean we would crave less of them since we have more capacity to store and use fat. Is it because carbs are fewer and farther between in nature? (At least pre industrial food production). It seems we could seek foods that reflect our body’s fuel systems. A little clarity would be helpful!
Why do we have such a primal response and increased hunger signals to sweet tastes?
That’s probably a big part of it. Since fruit would have been a relatively rare and comparatively sugar-rich food source, it makes some sense that when it’s available, we would eat it preferentially, and build up fat stores that would allow us to survive when less food is available.
The problem comes when such foods are ALWAYS available. Unless we avoid the sweets, those signals tend to lead to continuous intake of refined carbs.
In short, I think the “primal response” likely evolved as a survival mechanism, but one which is not needed in an environment in which food availability is no longer an issue.
Probably because the bulk of carby things (in most regions) was really only available at certain times of the year (summer/autumn) and not very much of it.
The insulin response from that period would signal to store fat, which is good if winters are harsh or amount to less available food through winter/spring.
So people who ate the most fruit, and put on the most fat were more likely to survive through to harsher seasons and have babies.
So basically its because fruit and such (sugar) helped us store more fat (preferred energy) for later when we needed it.
What about indigenous populations that live close to the equator and eat a very high carbohydrate diet of starchy roots and fruit? Do they experience the same increased hunger and scarcity response to those foods? I understand that processed carbs spike insulin and blood sugar more than less refined foods, but quite honestly I get just as much of a “gorge myself” response to fruit as I do to pop tarts. So if a population eats a diet high in “natural” sources of sugars do they also experience this desire to eat copious amounts of these foods? Or does the fact that their environment provides plenty of them prevent the gorging response? What about populations whose diets are very low in carbohydrate and where the abundant food source is fat? Do they experience stronger responses to carbohydrate when it is available? What about the high carb eaters? Do they forge themselves on fat when it is available? I am wondering about how the availability of different foods affects our hunger responses. I know that restriction will induce strong cravings for the foods that are off limits (either because they are not available in one’s environment or because we choose to restrict them). So I’m wondering how this plays out in cultures where their diets are either primarily fat or carbs, and therefore their bodies utilize different fuels.
There was a guy who went around looking at native populations looking at what they ate and rates of disease, and I believe he did show if they still ate what they were supposed to (e.g. available natively from the area) they were no more at risk of modern diseases than most people. So yes perhaps the “binge” urge is lessened due to a genetic component. Don’t quote me on that though…
Yes you’re thinking of Weston A Price. He mostly looked at dental health but I’m wondering more about hunger cues.
they don’t have winter. their bodies aren’t tuned to store fat. sugar excites the brain similarly to other stimulants like cocaine.
Interesting. So does this mean the ancestors of those populations also don’t store fat?
it means that by and large, people from equatorial areas are not genetically predisposed to store fat. sadly, these days, once these populations are introduced to a SAD they can defeat their genetics and start to baloon up in the typical type 2 diabetic response type (meaning trunk obesity).
however on a diet of whole, natural real food carbohydrate they generally do not put on a lot bodyfat, but that doesn’t mean they are immune from the other effects hyperinsulinemia
I haven’t eaten sweet stuff in quite some time (years?). I find the sweet smells of pastry shop and candy stores sickening. I generally feel like I should take a shower after leaving them (figuratively of course). However, when I was younger I loved the smell and the “food”. So IMHO I think some of the "primal response is more pavlovian than primal. But that’s just my 2 cents. That said, everyone seems to enjoy high blood sugar. Otherwise we’d have less diabetics.
Who knows though. My N=1 experiment could be just psychologically reassigning attraction for repulsion because I know sweet are bad for me.
It doesn’t make much sense that their genes would change so rapidly in response to dietary shifts. Funny how our bodies somehow go haywire when you would think they would respond to our benefit. Why would they suddenly start storing fat when eating processed versus natural forms of carbs? It would seem they would have the ability to have better utilization of all carbs no matter what form they start from.
I suspect it’s the caloric density, hyperpalatability, ease, low cost, convenience, and availability of such processed foods.
Compare this to a tuber you’d have spend energy to dig up, a coconut you’d have to climb and get, or an animal you had to hunt and kill. Even so-called native populations could out-eat their genetic predispositions in a generation or two.
In many (not all) ways, calories still matter.
I’d be interested to know how many countries actually eat seasonally now of indigenous foods.
Thanks, it’s just my theory and two cents on it. What do I know? 
Without getting too geeky on this, I wanted to mention the concept of “optimal foraging theory.” In essence, a species will take the least energy costly way of obtaining food. Those who find food easiest and with the least amount of energy expenditure will survive and thrive as a species. So, arguably, there’s a genetic preference for species who don’t spent time/risk/energy searching for food. So, deep down, even those peoples who traditionally have been very healthy may have an innate predisposition to epigentically “turn on” their optimal foraging gene once the 7-Eleven comes to town. “Hey, that was easy. Let’s store this stuff and do it again tomorrow!”
If you’re insomniatic tonight: http://bio.research.ucsc.edu/~barrylab/classes/CHAPTER_PDFS/Chap_6_Optimal.pdf
If that is the case, that those who expend the least amount of energy to find the most energy dense food, we should be thriving!
Right, but only if we ate the right things, at the right times. and in the right amounts. Many of us violate all three of those, sometimes all at once!
I was mostly making a joke, since we have apparently achieved the epitome of securing energy dense foods in the easiest manner possible
This makes a lot of sense. However, I have a nagging doubt about it all the same.
Did we not evolve from people living in the equatorial regions of Africa? People who (we suppose) had access to carbs most of the year round?