One of the most common, least questioned pieces of dietary advice is the Variety Hypothesis: that a more widely varied diet is better than a less varied diet. I think that this is false; most people’s diets are on the margin too varied.
There’s a low amount of variety necessary to ensure all nutrients are represented, after which adding more dietary variety is mostly negative. Institutional sources consistently overstate the importance of a varied diet, because this prevents failures of dietary advice from being too legible; if you tell someone to eat a varied diet, they can’t blame you if they’re diagnosed with a deficiency.
There are two reasons to be wary of variety. The first is that the more different foods you have, the less optimization you can put into each one. A top-50 list of best foods is going to be less good, on average, than a top-20 list. The second reason is that food cravings are learned, and excessive variety interferes with learning.
People have something in their minds, sometimes consciously accessible and sometimes not, which learns to distinguish subtly different variations of hunger, and learns to match those variations to specific foods which alleviate those specific hungers. This is how people are able to crave protein when they need protein, salt when they need salt, and so on.
If every meal you eat tastes different, you can’t instinctively learn the mapping between foods and nutrition, and can’t predict which foods will hit the spot. If you need and crave protein, and wind up eating something that doesn’t have protein in it, that’s bad.
If the dominant flavor of a food is spice, then as far as your sense of taste is concerned, its nutritional content is a mystery. If it’s a spice that imitates a nutrient, like MSG or aspartame, then instead of a mystery it’s a lie. Learning how to crave correctly is much harder now than it was in the past. This is further exacerbated by eating quickly, so that you don’t get the experience of feeling a food’s effects and seeing that food on your plate at the same time.
I’m not sure how to empirically measure what the optimum amount of variety is, but I notice I have builtin instincts which seem to seek it when I have fewer than 10 or so different meal-types in my habits, and to forget/discard meal-types when I have more than that; if this parameter is evolved, this seems like a reasonable guess for how varied diets should be.
The advice I’ve heard is to eat a variety of fruits and vegetables of different colors to get a variety of antioxidants in your diet.
Until recently, the thinking had been that the more antioxidants, the less oxidative stress, because all of those lonely electrons would quickly get paired up before they had the chance to start mucking things up in our cells. But that thinking has changed.
Drs. Cleva Villanueva and Robert Kross published a 2012 review titled “Antioxidant-Induced Stress” in the International Journal of Molecular Sciences. We spoke via Skype about the shifting understanding of antioxidants.
“Free radicals are not really the bad ones or antioxidants the good ones.” Villanueva told me. Their paper explains the process by which antioxidants themselves become reactive, after donating an electron to a free radical. But, in cases when a variety of antioxidants are present, like the way they come naturally in our food, they can act as a cascading buffer for each other as they in turn give up electrons to newly reactive molecules.
On a meta level, I don’t think we understand nutrition well enough to reason about it from first principles, so if the lore among dietitians is that people who eat a variety of foods are healthier, I think we should put stock in that.
Similarly: “Institutional sources consistently overstate the importance of a varied diet, because this prevents failures of dietary advice from being too legible; if you tell someone to eat a varied diet, they can’t blame you if they’re diagnosed with a deficiency.” But there’s a real point here, e.g. suppose that you have just a few standard meals, but all of the high-magnesium food items are being paired with phytates, and you end up magnesium deficient.
I agree that “varied diet” is a non-answer, because you didn’t tell me the exact distribution of food, but you are likely to blame me if I choose a wrong one.
Like, if I consume 1000 different kinds of sweets, is that a sufficiently varied diet? Obviously no, I am also supposed to eat some fruit and vegetables. Okay, then what about 998 different kinds of sweets, plus one apple, and one tomato? Obviously, wrong again, I am supposed to eat less sweets, more fruit and vegetables, plus some protein source, and a few more things.
So the point is that the person telling me to eat a “varied diet” actually had something more specific in mind, just didn’t tell me exactly, but still got angry at me for “misinterpreting” the advice, because I am supposed to know that this is not what they meant. Well, if I know exactly what you mean, then I don’t need to ask for an advice, do I?
(On the other hand, there is a thing that Soylent-like meals ignore, as far as I know, that there are some things that human metabolism cannot process at the same time. I don’t remember what exactly it is, but it’s something like human body needs X and also needs Y, but if you eat X and Y at the same time, only X will be processed, so you end up Y-deficient despite eating a hypothetically sufficient amount of Y. Which could probably be fixed by finding combinations like this, and then making variants like Soylent-A and Soylent-B which you are supposed to alternate eating. But as far as I know, no one cares about this, which kinda reduces my trust in the research behind Soylent-like meals, although I like the idea in abstract very much.)
I remember reading that some hunter-gatherers have diet breadth entirely set by the calorie per hour return rate: take the calories and time expended to acquire the food (eg effort to chase prey) against the calorie density of the food to get the caloric return rate, and compare that to the average expected calories per hour of continuing to look for some other food. Humans will include every food in their diet for which making an effort to go after that food has a higher expected return than continuing to search for something else, ie they’ll maximise variety in order to get calories faster. I can’t find the citation for it right now though. (Also I apologise if that explanation was garbled, it’s 2am)
Possibly because I consume sucralose regularly as a sweetener and have some negative impacts from sugar, it is definitely discerned and distinct from ‘sugar—will cause sugar effects’ to my tastes. I enjoy it for coffee and ice cream. I need more of it to balance out a bitter flavor, but don’t crave it for itself; accidentally making saccharine coffee doesn’t result in deciding to put splenda in tea later rather than go without or use honey.
For more pure sugar (candy, honey, syrup, possibly milk even), there’s definitely a saccharine-averse and a sugar-consume fighting at different kinds of craving for me. Past a certain amount, I don’t want more at the level of feeling like, oh, I could really use more sugar effects now; quite the opposite. But taste alone continues to be oddly desperate for it.
Fresh or frozen sweet fruit either lacks this aversion, or takes notably longer to reach it. I don’t taste a fruit and immediately anticipate having a bad time at a gut level. Remains delicious, though, and craved at the taste level.
Yeah, I came to a similar conclusion after looking at this question from Metaculus. I might have steered to far in the opposite direction, though. I have currently two meals in my rotation. At the very least one of them is “complete food” (So I worry less about nutrition and more about unlearning how to plan meals/cook).
One of the most common, least questioned pieces of dietary advice is the Variety Hypothesis: that a more widely varied diet is better than a less varied diet. I think that this is false; most people’s diets are on the margin too varied.
There’s a low amount of variety necessary to ensure all nutrients are represented, after which adding more dietary variety is mostly negative. Institutional sources consistently overstate the importance of a varied diet, because this prevents failures of dietary advice from being too legible; if you tell someone to eat a varied diet, they can’t blame you if they’re diagnosed with a deficiency.
There are two reasons to be wary of variety. The first is that the more different foods you have, the less optimization you can put into each one. A top-50 list of best foods is going to be less good, on average, than a top-20 list. The second reason is that food cravings are learned, and excessive variety interferes with learning.
People have something in their minds, sometimes consciously accessible and sometimes not, which learns to distinguish subtly different variations of hunger, and learns to match those variations to specific foods which alleviate those specific hungers. This is how people are able to crave protein when they need protein, salt when they need salt, and so on.
If every meal you eat tastes different, you can’t instinctively learn the mapping between foods and nutrition, and can’t predict which foods will hit the spot. If you need and crave protein, and wind up eating something that doesn’t have protein in it, that’s bad.
If the dominant flavor of a food is spice, then as far as your sense of taste is concerned, its nutritional content is a mystery. If it’s a spice that imitates a nutrient, like MSG or aspartame, then instead of a mystery it’s a lie. Learning how to crave correctly is much harder now than it was in the past. This is further exacerbated by eating quickly, so that you don’t get the experience of feeling a food’s effects and seeing that food on your plate at the same time.
I’m not sure how to empirically measure what the optimum amount of variety is, but I notice I have builtin instincts which seem to seek it when I have fewer than 10 or so different meal-types in my habits, and to forget/discard meal-types when I have more than that; if this parameter is evolved, this seems like a reasonable guess for how varied diets should be.
(Crossposted with Facebook)
The advice I’ve heard is to eat a variety of fruits and vegetables of different colors to get a variety of antioxidants in your diet.
https://blogs.scientificamerican.com/food-matters/antioxidant-supplements-too-much-of-a-kinda-good-thing/
On a meta level, I don’t think we understand nutrition well enough to reason about it from first principles, so if the lore among dietitians is that people who eat a variety of foods are healthier, I think we should put stock in that.
Similarly: “Institutional sources consistently overstate the importance of a varied diet, because this prevents failures of dietary advice from being too legible; if you tell someone to eat a varied diet, they can’t blame you if they’re diagnosed with a deficiency.” But there’s a real point here, e.g. suppose that you have just a few standard meals, but all of the high-magnesium food items are being paired with phytates, and you end up magnesium deficient.
I agree that “varied diet” is a non-answer, because you didn’t tell me the exact distribution of food, but you are likely to blame me if I choose a wrong one.
Like, if I consume 1000 different kinds of sweets, is that a sufficiently varied diet? Obviously no, I am also supposed to eat some fruit and vegetables. Okay, then what about 998 different kinds of sweets, plus one apple, and one tomato? Obviously, wrong again, I am supposed to eat less sweets, more fruit and vegetables, plus some protein source, and a few more things.
So the point is that the person telling me to eat a “varied diet” actually had something more specific in mind, just didn’t tell me exactly, but still got angry at me for “misinterpreting” the advice, because I am supposed to know that this is not what they meant. Well, if I know exactly what you mean, then I don’t need to ask for an advice, do I?
(On the other hand, there is a thing that Soylent-like meals ignore, as far as I know, that there are some things that human metabolism cannot process at the same time. I don’t remember what exactly it is, but it’s something like human body needs X and also needs Y, but if you eat X and Y at the same time, only X will be processed, so you end up Y-deficient despite eating a hypothetically sufficient amount of Y. Which could probably be fixed by finding combinations like this, and then making variants like Soylent-A and Soylent-B which you are supposed to alternate eating. But as far as I know, no one cares about this, which kinda reduces my trust in the research behind Soylent-like meals, although I like the idea in abstract very much.)
You may find this source interesting: https://onlinelibrary.wiley.com/doi/full/10.1002/ajpa.23148
I remember reading that some hunter-gatherers have diet breadth entirely set by the calorie per hour return rate: take the calories and time expended to acquire the food (eg effort to chase prey) against the calorie density of the food to get the caloric return rate, and compare that to the average expected calories per hour of continuing to look for some other food. Humans will include every food in their diet for which making an effort to go after that food has a higher expected return than continuing to search for something else, ie they’ll maximise variety in order to get calories faster. I can’t find the citation for it right now though. (Also I apologise if that explanation was garbled, it’s 2am)
Possibly because I consume sucralose regularly as a sweetener and have some negative impacts from sugar, it is definitely discerned and distinct from ‘sugar—will cause sugar effects’ to my tastes. I enjoy it for coffee and ice cream. I need more of it to balance out a bitter flavor, but don’t crave it for itself; accidentally making saccharine coffee doesn’t result in deciding to put splenda in tea later rather than go without or use honey.
For more pure sugar (candy, honey, syrup, possibly milk even), there’s definitely a saccharine-averse and a sugar-consume fighting at different kinds of craving for me. Past a certain amount, I don’t want more at the level of feeling like, oh, I could really use more sugar effects now; quite the opposite. But taste alone continues to be oddly desperate for it.
Fresh or frozen sweet fruit either lacks this aversion, or takes notably longer to reach it. I don’t taste a fruit and immediately anticipate having a bad time at a gut level. Remains delicious, though, and craved at the taste level.
Seems very plausible to me. Thanks for sharing.
Yeah, I came to a similar conclusion after looking at this question from Metaculus. I might have steered to far in the opposite direction, though. I have currently two meals in my rotation. At the very least one of them is “complete food” (So I worry less about nutrition and more about unlearning how to plan meals/cook).