The Last Conversation You’ll Ever Need to Have About Eating Right

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It’s beyond strange that so many humans are clueless about how they should feed themselves. Every wild species on the planet knows how to do it; presumably ours did, too, before our oversized brains found new ways to complicate things. Now, we’re the only species that can be baffled about the “right” way to eat.

Really, we know how we should eat, but that understanding is continually undermined by hyperbolic headlines, internet echo chambers, and predatory profiteers all too happy to peddle purposefully addictive junk food and nutrition-limiting fad diets. Eating well remains difficult not because it’s complicated but because the choices are hard even when they’re clear.

With that in mind, we offered friends, readers, and anyone else we encountered one simple request: Ask us anything at all about diet and nutrition and we will give you an answer that is grounded in real scientific consensus, with no “healthy-ish” chit-chat, nary a mention of “wellness,” and no goal other than to cut through all the noise and help everyone see how simple it is to eat well.

Here, then, are the exhaustively assembled, thoroughly researched, meticulously detailed answers to any and all of your dietary questions.

Just tell me. Ethical concerns aside, which diet is the best: vegan, vegetarian, or omnivorous?
We don’t know, because the study to prove that any one diet is “best” for human health hasn’t been done, and probably can’t be. So, for our health, the “best” diet is a theme: an emphasis on vegetables, fruits, whole grains, beans, lentils, nuts, seeds, and plain water for thirst. That can be with or without seafood; with or without dairy; with or without eggs; with or without some meat; high or low in total fat.

Okay, well what about the “diets” I keep trying? I just started the paleo diet. Will it change my life?
A genuine paleo diet is almost certainly good for human health, since it’s a diet to which we are adapted. But what is a true paleo diet?

It’s, you know, eating paleo. Like meat. And fruit. And eggs? And bacon!
It is certainly not a blanket license to eat bacon. And it’s not a good reason to give up whole grains, either. Nor do you need to eat eggs, or even meat.

What about burgers or pepperoni? They’re paleo, right?
There were no Paleolithic burgers, or pepperoni. There was also no paleolithic bacon.

So what can I eat?
This is a good place to start because the real experts in Stone Age nutrition think our ancestors — who, by the way, were foragers — consumed a wide variety of ever-changing plant foods that gave them up to 100 grams of fiber daily. We, on the other hand, eat an average of 15 grams of daily fiber. Our forebears are thought to have eaten lots of insects, too. (Few people espousing the virtues of “Paleo” seem inclined to try that out.) They probably ate grains, with some evidence they did so 100,000 years or more ago. And, of course, they ate the meat of only wild animals, since there were no domesticated animals in the Stone Age, with the possible exception of the wolf-to-dog transition.

In any event, the diet to which we are adapted is almost certainly much better for health, and reversing illness, than the prevailing modern diet. There is abundant evidence of disease-reversal with diets of whole, minimally processed food; plant-predominant diets; and even plant-exclusive diets.

So plants are good. Maybe I’ll just do a juice cleanse instead. Wait — are juice cleanses dangerous?
Generally not, depending on your health at the start, but neither are they useful.

Don’t they cleanse your body?
The general claim is that they actually do “cleanse” you — but of what?

Um, toxins?
The body detoxifies itself daily; that’s a primary job of the liver and the kidneys, and they are really good at it. (The intestines, spleen, and immune system are in on it, too.) So, you want to take good care of your liver and kidneys, gut, and immune system. That’s a far better “cleanse” than any juice. How do you take good care of all your detoxifying organ systems? By taking good care of yourself, of course. That means eating well, not smoking, exercising, sleeping enough, managing your stress, and so on.

My friend is always talking about “inducing ketosis.” What is he babbling on about?
A ketogenic diet is one diet that starves the body of glucose sources so that it’s forced to burn ketone bodies — products of fat metabolism — as fuel.

Is that … healthy?
There is no evidence that such diets are conducive to good health in the long run, and no evidence they are better than other, more sustainable diets at health transformation or weight loss in the short run.

But he’s losing weight.
Not everything that causes weight loss or apparent metabolic improvement in the short term is a good idea. Cholera, for instance, causes weight, blood sugar, and blood lipids to come down — that doesn’t mean you want it! The only use of a ketogenic diet that is clearly medically justified is to treat refractory seizures in select cases, mostly in children.

Which is better: a plant-based diet with carbs, or a low-carb diet with meat?
The evidence of every variety overwhelmingly highlights the benefits of plant-predominant diets for the health outcomes that matter most: years in life, and life in years; longevity, and vitality. Forget about “carbs,” and think instead in terms of the foods that are best for you.

Mark Bittman’s Buffalo Shrimp With Blue Cheese

If there’s one thing I know for sure, it’s that carbs are evil.
This is probably the silliest of all the silly, pop-culture propaganda about diet and health. All plant foods are carbohydrate sources.

Yeah, but: Carbs are evil.
Everything from lentils to lollipops, pinto beans to jelly beans, tree nuts to doughnuts, is a carbohydrate source. Most plant foods are mostly carbohydrate. So if “all carbs” are evil, then so are vegetables, fruits, whole grains, beans, lentils, nuts, and seeds.

Sure, but, I should still avoid carbs, right?
Exactly the opposite is true. You cannot have a complete or healthful diet without carbohydrate sources.

Why have I been led to believe that carbs are evil?
Highly processed grains and added sugar are bad, not because they are carbohydrate, but because they’ve been robbed of nutrients, they raise insulin levels, and they’re often high in added fats, sodium, and weird ingredients. Carbs are not evil; junk food is evil.

What about gluten? It seems like everyone is kind of gluten-intolerant now.
On the contrary: Statistically, a small percentage of the population is gluten intolerant. About one percent of people have celiac disease, and perhaps 10 percent have lesser forms of sensitivity, which may be related to other factors, like a disrupted microbiome. But still, 90 percent of people have no problem digesting gluten.

So if you’re not gluten intolerant, and if you don’t have celiac disease, is bread really that bad for you?
No.

Should I eat whole-grain bread?
There’s a big difference between white bread and whole-grain bread, and you certainly don’t need to eat bread to have an optimal diet. But an optimal diet leaves room for good bread — whole grain especially — and we think good bread is one of life’s great pleasures. Eat it for that reason.

I want to lose weight. Is diet really more important than exercise?
Yes. It is much easier to outeat running than to outrun all of the tempting calories that modern marketing encourages us to cram in. Both diet and exercise are important to health, and exercise is important in weight maintenance. But to lose weight, the preferential focus needs to be on controlling calories in, more than calories out.

I keep hearing that lectins are toxic and make weight loss harder. What’s the deal?
The deal with lectins is that making them into a bogeyman was a great way to sell yet another fad diet book. Lectins are distributed across almost the entire expanse of foods consumed by humans, and concentrated in some of the foods most decisively linked to health benefits, such as beans and lentils, along with many fruits and vegetables.

Oh yeah, and what’s up with beans? I’ve heard they’re low in fat, high in protein, and high in fiber. However, I also read that they are digestive irritants and slightly toxic due to the lectin content.
The single most salient commonality among all the Blue Zone diets — the diets around the world associated with longevity and vitality — is beans. Beans are really, really, really good for us. Identifying compounds in beans that are potentially “toxic” is like noting that air contains oxygen, which can be toxic.

But also: Beans make me fart.
Some people have a hard time digesting beans, and might benefit from enzyme support, such as Beano. All beans should be cooked; they are nearly impossible for any of us to digest when raw. Despite all the nonsense, the bottom line is that beans are among the most beneficial foods for human health, and offer enormous environmental benefits as well.

Given the prevalence of heart disease associated with poor diets in the U.S., we say bring on the beans! (And, as far as farting is concerned, anecdotally at least, the more frequently you eat beans the better your gut tolerates them.)

Since we’re already talking about farts: I’m all for eating foods like whole grains, nuts, legumes, fruits, and vegetables, but they sometimes — okay, often — make me gassy and bloated. That doesn’t happen when I eat “less healthy” foods.
This could be a food allergy or sensitivity, irritable bowel syndrome, or a problem with your microbiome. All of these can be addressed, but you need a clear diagnosis first. So this is an issue you should take to a doctor who can evaluate you, specifically. You should be able to have a healthful diet, and alleviate these symptoms, too.

Do I have to eat grains if I want to be healthy?
No, but optimizing your diet, and thus your health, is harder if you exclude whole grains, which are highly nutritious. Among their virtues: they are rich in fiber, which tends to be very deficient in the typical American diet — that 15 grams we all tend to eat is half the daily recommended intake. So, if cutting out whole grains lowers your already-low fiber intake further, that’s no good!

My friend never eats fruits and vegetables and is quite proud of that. Is it possible to be healthy without eating fruits and vegetables?
A qualified “no.” Although nuts and seeds are really fruits, and beans and legumes and grains are really vegetables of a sort, we will go the other way and say they are separate. So, you could, in principle, have a diet rich in beans, lentils, chickpeas, whole grains, nuts, seeds, and perhaps fish and seafood, and it would almost certainly be better than the prevailing modern diets of fast food, processed meat, and junk. But as good as the same diet with vegetables and fruits? No way.

If I want to lose weight, should I eat less? And if I eat less, will my metabolism really slow down?
If you starve yourself, yes. And if you lose weight, yes, because a smaller body burns fewer calories than a larger one. The effects tend to be modest, however, unless the weight loss is extreme. You can compensate with exercise, and building some muscle, both of which increase your metabolic rate.

What kinds of foods do you think will help support weight loss?
Wholesome, whole, unprocessed plant foods in particular. And, any food you eat while riding in the Tour de France.

What should I care about on nutrition labels? Calories, fat grams, or sugar grams?
The best foods don’t even have labels, because they are just one ingredient: avocado, lentils, blueberries, broccoli, almonds, etc.

Okay, sure. But what about the ones with labels?
When foods do have labels, look for a short ingredient list of things you recognize as actual food. If the ingredients are wholesome, the nutrient profile will be fine. If the ingredient list is dubious — chemicals, various kinds of added sugar, questionable oils, sodium, and so on — the nutrient profile will be, too. It is really the overall nutritional quality of the food, rather than any one nutrient, that matters. For help getting it right, that even an 8-year-old can use, see here.

Cut through the hype: Cold-pressed coconut oil is neither “good” nor “bad,” but olive oil is a better choice; carbs are not evil, and an optimal diet allows for whole-grain bread. Photo: Bobby Doherty/New York Magazine

What about intermittent fasting? Is that actually effective for better gut health and energy levels?
It’s “effective” relative to doing nothing.

I can eat how I want and then just occasionally fast to “reset” my diet?
No. Fasting is not more effective than limiting calorie intake every day. Fasting is a way to control average, daily food intake — but not the only way. If it works for you, it’s a reasonable option, but it does not involve any magic.

Can I just eat the same thing every day?
Yes, that’s quite reasonable. Variety over time is important to the quality of a diet, but that can be concentrated at dinner if you prefer. So, for instance, how about whole grains (hot or cold), mixed fruits, and nuts for breakfast — every day? Then, how about a salad, soup, or stew of mixed vegetables and beans or lentils for lunch? And then for dinner, a wholesome variety of choices.

Is there really such a thing as a superfood?
If the idea is that a superfood will do super things, then no.

Yeah, except for quinoa, right? Which is magical or something.
No single food, separate from the overall quality and pattern of diet, exerts a major health effect. If your diet is excellent, no single food will be responsible for the benefits. If your diet is terrible, no single food will compensate.

If “super” means the nutrient profile rather than the effects of a food, then … okay: A food that has an especially high ratio of many valuable nutrients relative to calories, and a very low amount of any detrimental nutrients like sugar or saturated fat could be called “super.” But this would not just pertain to exotic berries from neighboring solar systems. This would apply to foods like spinach, broccoli, blueberries, chickpeas, pinto beans, lentils, kale, peaches, or walnuts.

What about avocados? Are they bad for you or good for you? Everyone says they’re full of fat, but that it’s “good” fat.
Think of avocados as you do nuts: They’re “good for you” but with limits. One a day is certainly fine. Their nutrient profile is great, with fat that’s a lot like the fat in olives.

Which is good fat?
Yes.

Which is different from “bad” fat.
Yes.

So what’s the difference between good fat and bad fat? I’ve heard I need to avoid saturated fat.
In the diet, what really matters most is balance. Saturated fat, for instance, is bad not because it is “bad” — there is some in even highly nutritious foods — but because we get too much of it. And too much is bad.

How do I get that fat balance?
To get the right balance of fats in our diet, with an emphasis on a mix of polyunsaturated fats, omega-6, omega-3, and monounsaturated fats, we need a balance of foods. Get the “right” fats from nuts, seeds, olives, avocado, and seafood, and use the best cooking oils: extra virgin olive oil tops that list. To avoid an excess, limit the intake of foods high in saturated fat. That includes most meats, and full-fat dairy. And all junk food is suspect for all sorts of reasons.

What about animal fats like lard or tallow? They’re natural so they must be good, right?
All fat sources are a mix of different fatty acids; almost all fats and oils contain a mix of fat varieties: saturated, polyunsaturated, and monounsaturated. Lard is almost 40 percent saturated fat; and tallow is more than 50 percent saturated. That’s a lot.

Since the world’s best diets consistently derive 10 percent or less of their calories from saturated fat, raising the average amount of saturated fat in your diet makes no sense. And there are other factors: Unlike oils that are predominantly unsaturated, such as olive oil, there is no evidence of a health benefit from lard or tallow.

Olive oil. Got it. That one I knew. What about coconut oil? First I heard it’s good for me. Then I heard it’s bad for me.
There’s certainly no evidence it’s “good” for you, but organic, cold-pressed varieties are probably not “bad” for you, either. But olive oil and cold-pressed canola oil are better choices.

Organic, obviously. Even I know that organic is better. Right? It’s certainly more expensive. Tell me it’s better.
Yes. Unquestionably. For many reasons, including that organic farming protects farmworkers from harmful pesticides. There are also clear environmental and ethical benefits.

But … is it healthier?
Proving specific health benefits for organic food is nearly impossible: Imagine a randomized trial comparing only organic food to no organic food, but exactly matched in every other way.

Okay, I’ll stick with organic. Should I take probiotics?
We know pretty reliably that bad microbiomes are common, and that the “right” gut microbes foster good digestion, robust immunity, better sleep, and even weight control —

Okay, sounds good, but — what about probiotics?
In order to foster a healthy microbiome —

Yes, okay, but — what is the microbiome?
Your microbiome is the ecosystem of diverse bacteria that flourishes, quite naturally, in your digestive system. It’s a part of you; as you get healthier, so does it — and quickly. Whole foods, minimally processed, mostly plants, and plain water are good places to start.

One of the current gimmicks — which helps to sell books — is the idea that you have to eat to feed your microbiome. But let’s face it: every wild species on the planet knows what to eat, and none of them know anything about their microbiota. They eat the foods to which they are adapted, and the bugs adapted to live inside them thrive as they do. There’s a lesson for us there: fixing what’s broken is good, and probiotics may be one way of doing it. A balanced diet is a near-certain way.

Okay — so what are probiotics again?
Probiotics are supplements that encourage the repopulation of a healthy microbiome. Think of it like putting high-quality grass seed on a distressed lawn.

Can you “overdose” on probiotics?
In theory, an overdose could result in something called a “dysbiosis,” where the gut is overgrown with an imbalance of organisms. But it must be very hard to do, since we’re not aware of any cases.

What happens if I eat too much yogurt?
We have no idea. Probably you get full.

Fruits and vegetables that are flash-frozen are likely to retain more nutrients than “fresh” fruits and vegetables imported from far away. Photo: Bobby Doherty

What about vegetables? I’ve heard frozen can be healthier than fresh — is that possibly true?
There are instances of frozen vegetables being of higher quality and higher nutritional content than “fresh” vegetables. This is particularly true when produce is “flash frozen,” meaning frozen quickly at very low temperature right after harvesting. Age is everything, and freezing retards aging. So, “fresh” produce that comes from far away is likely to lose some of its nutrient value during the transit time, whereas frozen produce is more likely to preserve the nutrients it had at the start of its journey. The best vegetables are likely to be fresh and locally sourced, but flash frozen is nearly as good, and those “fresh” vegetables that spend a long time in storage or transit are probably the least nutritious.

Does cooking food make it less healthy?
Yes and no: Heat can damage some antioxidants, so raw berries are more nutritious than cooked. But cooking can make some food more nutritious: We can’t even eat (let alone digest) dried beans and lentils without cooking them; but cooked, they’re among the most nutritious and health-promoting of all foods. The antioxidant that makes tomatoes red, lycopene, is more “bioavailable” (our metabolism can access it more easily) when cooked than when tomatoes are eaten raw. Cabbage and other brassicas — including broccoli and most dark, leafy greens — are more readily digested with gentle cooking as well.

What about soy? Is soy good or bad for me?
Soy foods come in many varieties, and many are highly processed, so suffer the same liabilities of all highly processed foods; they’re high in refined starches, heated oils, added sugar and salt, and low in nutrients and fiber.

So what kind of soy should I eat?
Traditional soy foods such as tofu and tempeh are good for you, largely because they provide sound nutrition and because they usually displace meat. Soy as a supplement is less clearly a good idea.

I heard that processed soy products are linked to cancer.
The estrogen-like compounds in soy can promote cancer growth in animals in labs, but the net effect of eating foods like tofu and tempeh is less cancer, not more.

Here’s a stumper. I always hear I should eat more fish for lean protein. But then I also always hear that too much fish exposes me to toxins like mercury. Which is it?
Fish is unquestionably the healthiest animal protein to eat. However: There are huge sustainability issues, and some fish — especially large, predatory fish, like big species of tuna and mackerel, and swordfish and shark — concentrate mercury by eating smaller fish.

That doesn’t really answer my question.
Like anything else, fish shouldn’t be eaten three times a day. Should it be eaten once a day? If it’s your only animal product, and it’s sustainable and not otherwise tainted, yeah. Smaller fish are far less likely to contain mercury than big ones.