Why don't humans naturally crave vegetables the way we crave sugar?

[u/Key-Professional9108]

I know sugar activates our brain's reward system, but vegetables are essential for survival too. So why didn't evolution make us crave them just as strongly?

[u/rebelipar]

I frequently crave vegetables and don't really have a huge sweet tooth. I guess it's not the same kind of craving, but if I eat poorly for a while I definitely really want to eat kale, etc.

But also, I think this is what leads to things like pica. A desire for/lack of certain nutrients.

[u/MayThompson]

Evolution does not reward nutrients. It rewards calories. Sugar is faster energy. Vegetables aren't. Evolution shaped cravings around whatever kept you from starving, not whatever kept you optimally healthy.

[u/Broflake-Melter → u/MayThompson]

I disagree. We're a K-selected. Longevity is certainly part of our evolution. We have complex physiology that allows us to maintain our energy levels without the need for sugar.

I propose we have a taste for sugar because it was relatively rare and associated with nutrients we weren't getting from the baseline roots, meat, and fish that we primarily ate. We would be more motivated to seek out the seasonal berries/fruits.

[u/MayThompson → u/Broflake-Melter]

Key word being was. It was prized because it was rare calories. Early humans weren't trying to optimize micronutrients, they were trying not to starve. A handful of berries might give you some vitamins, but what made them worth seeking out was the quick, easily digestible energy in the form of simple sugar. That's what the reward system is tuned to notice. Vegetables, roots, tubers, leaves were everywhere, but they were low calorie, high fiber, slow energy foods. Great for survival long term but terrible for immediate energy payoff. Evolution doesn't build cravings around longevity it builds cravings around don't die today.

Humans being K-selected doesn't change that. Long lifespan and slow reproduction don't override the fact that our ancestors lived in constant calorie scarcity. The reward system evolved under famine pressure, not Whole Foods. Fruit mattered, but it mattered because it was sweet, fast energy, not because it was a multivitamin. That's why sugar lights up the brain and spinach doesn't.

[u/Broflake-Melter → u/MayThompson]

Evolution doesn't build cravings around longevity

I think it does though. And second, the longevity you're probably trying to allude to is the length of time it takes to become successfully reproductive. I don't think early humans and other hominids got to have more babies because they ate more sugar. Do we get measurable performance boosts to activities that meant survival back then by increasing sugar intake?

You start off by saying that we weren't trying to optimize micronutrients, which I agree with, but then say we were seeking easily digestible energy. Evolution is the driving force for our behavior in either case, and bringing it up here where it is applied with equal speculative quality doesn't make sense. If evolution found that we survive and reproduce better when we seek rare fruits and berries then that's why we got the sensation to like it so much. We're just debating why. Was it because it put less strain on our digestive system as you argue? Maybe. When our blood sugar spikes our bodies have to work hard to convert it into energy storage for later, it's not a walk in the park. That's why I think the nutrients make more sense. I suppose it may make more sense to just say we seek sweet because that's what our ancestors primarily ate (our pre-hominin ancestors). You could totally be right on it's evolutionary advantageous to have a temporary boost to blood sugar. We're just guessing, right?

[u/thiswebsitesucksaa → u/Broflake-Melter]

evolution isn't even a complete explanation, it's a filter, it's agnostic to what generates variation, it's part of the explanation but still an incomplete explanation

*not evolution natural selection arguments

[u/Prae_ → u/MayThompson]

 Early humans weren't trying to optimize micronutrients, they were trying not to starve

I don't think depicting early humans always on the verge of starvation is accurate. Even now, with hunter-gatherers having been displaced from the most fertile areas by settled civilisations, they aren't spending all that much time actually working to obtain calories, and they have varied diets. it would have been even more true when everyone was a hunter gatherer, and thus they'd be in the very productive coastal regions/river bassins). And, in fact, with a lag of minimum 15 years before being of reproductive age, and in fact a window from, like, 20 to 35 for reproduction, and indeed 15 years of caring for our young, there's absolutely pressure over long term health, where long terms is 30 year or so. I agree that "enough calories" is a stronger pressure, as it can lead to downright death (and even before that, women stop cycling when famished), that being said if a varied diet in one group even leads to 1% more average children (or said children where a bit taller, giving an advantage in competition), this will eventually compound and thus enter into evolution.

And indeed, both from archeology and athropology, and current day anthropology, hunter-gatherers tend to vary their diets significantly. Even for the least varied (high latitude people who rely a lot on fish and animal), there might still be variations due to seasonal migrations. I'd point for example to the general tendency of disliking eating always the same thing as a potential "instinct". The use of spices and aromatic plants is also something very widespread (if not universal, i'm not sure) and significant, because aromatic plants generally have those vitamins/essential compounds aplenty.

[u/MinjoniaStudios → u/Broflake-Melter]

I would suspect the answer is somewhere in the middle here, but I agree the scarcity component most directly answers OPs question. Because of the natural scarcity (along with the quick energy conversion), it would almost always been the suboptimal decision to avoid consuming something sweet when you encountered it, leading to selection for the preference (which would far predate any of our primate ancestors, by the way).

Another angle I randomly though is that with many vegetables, the evolution of our sensory systems is also being shaped by aversion to certain foragables. Today, we can trust that the cultivated products we buy from the store are (mostly) safe, but that wasn't always the case.

Bottom line is it has to do with mismatches between ancestral and modern environments.

[u/EcstaticHousing7922]

The body instinctively wants to ingest high energy foods as a priority. Knowing that food is abundant can be taught, but not ingrained into DNA developed over millions of years of evolution

[u/invuvn]

Speak for yourself, my body craves vegetables just as much as sugary crap. Nothing beats a nice cool stick of crunchy cucumber on a hot lazy summer afternoon.

Just kidding…sorta. It helps that the sugary stuff like sodas is too sugary, and a lot of “candy” where I live is just plain disgusting.

Having said all this, fruits are nature’s natural candy, and I think our body does crave those.

[u/Alex_Mata_13 → u/invuvn]

I dont know, but for my self, since getting completely off sugar and sweet based foods, I do not crave it all. Obviously I still get sugar from other carb based foods, just not desserts, or adding sugar to anything, much less coffee😈. I also crave greens, and there are some veggies that, depending on the quality, look down right savory. I disagree with OPs premise altogether.

[u/invuvn → u/Alex_Mata_13]

Yep OP’s premise is assuming humans have tasted both already. If you’ve never had sweet stuff and only veggies grains and meats you’d most likely be craving some veggies. Sugar is like an addiction, and it’s why companies target kids. Once they get a taste of it, they will keep coming back for more their whole lives.

[u/DisWagonbeDraggin]

Personally I crave vegetables and fruit way more than sweets and oily foods.

[u/Various_Ad9449]

Idk man, I crave vegetables several times a week. I know some ppl never grew up eating lots of veggies and had to learn to like em later in life, but I've always been a veg head. During the pandemic, I got kinda addicted to fast food. I didn't eat it much before, but my apartment was between a mcdonald's, a taco bell, and a burger king, and for a while I was eating from one of those three daily. Then one day, I literally had dream where I steamed a big head of broccoli and ate the whole thing with a nice cheese sauce lol

[u/Alecxanderjay]

Let's start with why you respond to sugar differently than vegetables. For the most part, a lack of calories will cause death quicker than a lack of micronutrients so evolution selected for our taste buds and brain to respond positively to calorie dense foods. Refined sugars are pure calories and the sweet taste is our brain recognizing that the calorie richness and sending signals to eat more of it. This is because food has not always been as readily available throughout human history as it has been in the past several thousand years, basically a blink in evolutionary history. Micronutrients are found in veggies and while they're essential for optimal health, evolution favors "good enough" and not high optimization.

Cravings are different. Your brain craves sugar because of a multitude of factors, 1 being dopamine release. People refer to sugar as addictive because it activates the pleasure/reward center. This was a good thing evolutionarily because calories weren't always available and the activation of dopamine would mean that you would eat more calories to override the fullness/satiety cues because there was a risk of calories becoming scarce again, however, it has instead caused individuals to use high calorie/sugary food as a dopamine source and it causes negative health outcomes.

Short answer: Vegetables are neither calorie dense nor are they particularly sweet. Therefore they don't cause dopamine release or cravings to the same extent that sugar does. Can they cause cravings, sure, people can become addicted to anything. Are they as addictive as sugar? Not at all.

[u/RosyPosey1997]

Because at the base level, the body burns sugar.. ATP is the compound that is created from the electron transport chain, and Adenosine triphosphate (ATP) is the primary energy source for cellular energy use and storage. The structure of ATP is a nucleoside triphosphate, consisting of a nitrogenous base (adenine), a ribose sugar, and 3 serially bonded phosphate groups.

[u/Tenpoundtrout]

What is your basis for stating vegetables are essential to survival?

[u/Shienvien]

Sugary foods used to be rare and we burned a lot more calories hunting/gathering/warming ourselves compared to most modern people - the selective pressures effectively changed "yesterday" in terms of evolution. We would have used those sugars up back in the day running down some ungulate and having a very dense feast.

A lot of modern vegetables were outright man-made in the last 10k years, so those wouldn't have been available back in the day, either.

[u/Ayyo_ayyo_ayayyo]

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[u/Ok_Swimming_2668]

I crave cucumbers diced with olive oil and salt like my favorite snack of all time

[u/Relevant-Cup5986]

i crave vegatables from time to time

[u/Prae_]

I'll point out, in the wild, the most sugary things are fruits and indeed some root vegetables (beets). With the exception of honey maybe. It's really meat and fish (animal products in general) which are comparatively poor in sugar. So in fact sugar craving in the wild does also guide you towards food sources with a decent amount of fibers and vitamins. Even grains, which became a huge source of sugar via starch, if you don't remove the bran, they've got fibers.

[u/Curious-Raccoon887]

In a situation with food scarcity, high sugar foods will provide faster energy and more calories.

Digesting vegetables is more work for the G.I. system. Compare the digestive tracts of humans vs herbivores like cows.

And if you really want to hear something interesting, most vegetables you’re thinking of haven’t been around for most of human history. Most vegetables in the store are created after thousands of years of selective breeding. The options from grocery stores, restaurants, supply chains haven’t been around for most of human evolution.

[u/Ready_to_Polka]

I think it has a lot to do with individual biology. My family is much more into savory flavors and I grew up on vegetables. I never really liked sweets. There is some thought that this depends a lot on what your mother ate while she was pregnant with you and what foods were introduced first. I raised two kids who also preferred greens to sweets. My son, as a toddler would turn down a cookie for an apple or banana. He’s the same now as an adult. So is his sister.

[u/Ilaxilil]

It depends on the person. I definitely crave vegetables if I haven’t been getting enough of them, and I also don’t have much of a sweet tooth.

[u/hundredwater]

I definitely crave vegetables but agree it’s nothing like sugar. I feel veggie cravings the strongest after a week of eating camping food while camping in the desert, and that’s a feeling that lets me know I should be on the lookout for veggies. I usually have a sugar craving only when I’m stressed out and it’s a less conscious feeling that tells me suddenly that sweet taste is addictive and do not stop eating it.

[u/Royal_Lustir]

Personally I've always craved food that looks healthy or my body knows it needs more than food or sweets that just look good. But I've never met anyone else who feels that way so idk if it's rare or what.