Why Ultra-Processed Foods Cause Weight Gain

00:00:00.000 | So these ultra-processed foods have a number of features that make them, make people prone

00:00:07.800 | to gain weight.

00:00:08.800 | And there's really beautiful work, I don't know if you know this, from Kevin Hall at

00:00:11.160 | the NIH who's investigated this.

00:00:12.840 | He's really, in my opinion, the best person doing this kind of human obesity research

00:00:16.680 | today.

00:00:17.680 | And he does these experiments where he takes people into the NIH, into the hospital, hospitalizes

00:00:21.680 | them for several weeks so he can exactly control what they eat.

00:00:24.200 | And he did this beautiful experiment where basically he had chefs prepare two kinds of

00:00:28.480 | food, one ultra-processed and the other not ultra-processed, sort of more whole foods,

00:00:33.760 | more healthier foods, but had them take a lot of care so that when they gave the foods

00:00:38.760 | to independent raters, to people to test, they would say, "This is about equally palatable."

00:00:42.240 | So I like this ultra-processed dish as much as this non-ultra-processed dish.

00:00:47.240 | What's an example of an ultra-processed dish, like an out-of-package macaroni and cheese?

00:00:51.040 | Exactly, that kind of stuff.

00:00:52.040 | With bacon kind of thing?

00:00:53.040 | Exactly.

00:00:54.040 | Versus some pasta sitting next to a vegetable and a nice piece of...

00:00:58.440 | Salmon or something.

00:00:59.440 | Exactly, exactly.

00:01:00.440 | Okay.

00:01:01.440 | And took people into the hospital, basically allowed them to eat just as much as they would

00:01:07.760 | like first of the ultra-processed meals.

00:01:11.040 | So they had the selection of ultra-processed meals for a couple of weeks, and then switched

00:01:14.920 | them to the non-ultra-processed meals, and then also did it in the reverse order.

00:01:18.480 | So the other half of the people, they got the regular food first, then they got the

00:01:20.600 | ultra-processed food.

00:01:21.600 | And what he found is that even though people rated the foods as equally palatable, they

00:01:26.760 | ate much more of the ultra-processed food.

00:01:28.680 | And they actually gained weight during that two-week period when they were being given

00:01:32.120 | the ultra-processed foods.

00:01:33.120 | And then when you switched them, they lost weight.

00:01:35.160 | So the idea being that you can have two sets of food that you have equal preferences for,

00:01:41.000 | but something about the ultra-processed food is making you eat more of it when you actually

00:01:44.160 | consume it.

00:01:45.160 | And there's a number of ideas about why that could be.

00:01:47.120 | So one idea is that these ultra-processed foods have been optimized to have the right

00:01:51.800 | percentage of fat and sugar and protein to sort of promote more consumption once you

00:01:56.280 | start eating it.

00:01:57.280 | So that could be part of it.

00:01:58.600 | Another idea is that, you know, a big thing about whole foods is that they take more energy

00:02:03.400 | to digest and they have more volume.

00:02:05.040 | So one of the striking things from that study is if you just look at the pictures of the

00:02:08.560 | meals, they're the same number of calories, but there's so much more food, seemingly,

00:02:12.880 | on the non-processed food versus the ultra-processed food.

00:02:15.040 | And that's just because whole foods are bigger, because they're not so energy dense.

00:02:19.720 | And we know that, for example, volume is a major signal in the short term for regulating

00:02:23.440 | food intake.

00:02:24.440 | So if you just eat more volume, that could be valuable.

00:02:27.560 | And there's lots of things like that.

00:02:28.720 | So I think that's another plausible hypothesis, but the truth is we don't really know.

00:02:33.120 | - I have a hypothesis and I don't want to force you into speculation, but given that

00:02:37.240 | you've studied and discovered that the neurons and circuits involved in appetitive and consummatory

00:02:44.800 | behaviors can learn based on experience and expectation, I think it's fair game to at

00:02:50.920 | least ask your thoughts on this.

00:02:52.680 | So I've been paying a lot of attention to the landscape of what the general public think

00:02:57.960 | about, let's call them elimination diets, where people will just eat meat, or will go

00:03:05.780 | onto a vegan diet, or do some time-restricted feeding, or do any number of different things

00:03:11.000 | that have been shown to promote weight loss, provided people obey the laws of thermodynamics

00:03:17.140 | and consume fewer calories than they burn.

00:03:21.160 | I do believe in calories in, calories out, and there are a number of different routes

00:03:24.540 | to get there, and some are more painful, some are less painful, and it depends on the individual

00:03:29.560 | lifestyle exercise and on and on.

00:03:32.320 | But let's just suppose for a moment, based on Kevin's work on highly processed foods

00:03:39.000 | versus whole foods, that there's a learning that takes place when we eat, and that this

00:03:45.000 | learning takes place over time, such that our brain and appetite start to link the variables

00:03:50.600 | of taste, macronutrients, proteins, fats, and carbohydrates, so knowledge about macronutrients,

00:03:57.920 | a piece of fish is mostly protein, has some fat, a bowl of rice is mostly carbohydrate,

00:04:04.480 | has some protein, put a pat of butter on it, has some fat also, it's sort of obvious.

00:04:10.520 | But taste, macronutrient content, calories, which we already know people with anorexia

00:04:19.540 | are exquisitely good at counting with their eyes.

00:04:24.380 | So it's possible they represent, again, a pathologic extreme of this.

00:04:29.080 | And micronutrient content, maybe even amino acid content, like how much leucine is there.

00:04:35.560 | Now, most people aren't thinking about how much leucine is in a meal, but we know that

00:04:39.640 | leucine is important for certain aspects of muscle metabolism.

00:04:43.280 | It's present in certain proteins and not others.

00:04:45.840 | You're going to find less of it in a vegetable, typically, than you would in a piece of chicken

00:04:50.600 | and so on.

00:04:51.960 | And that when people eat mostly non-processed or minimally processed foods and not in combination,

00:04:59.160 | so we're not talking about stewing all this together or blending all of it together, which

00:05:03.480 | sounds disgusting, right?

00:05:04.480 | Broccoli, rice, and a chicken breast blend together, it just sounds horrible, but eating

00:05:07.360 | them separately, if there's some olive oil and a little pat of butter involved, like

00:05:10.240 | that sounds pretty good.

00:05:11.940 | But a highly processed food in some ways is a blending together of macronutrients, micronutrients,

00:05:19.140 | if there are any, and other features of the food that neurons in the brain seem to pay

00:05:25.180 | attention to, and then giving it a unified taste, a Dorito, right?

00:05:30.420 | A candy bar that we attach to the product, we attach to the name of the processed food,

00:05:36.780 | to the packaging.

00:05:38.400 | But I could imagine, and here's the hypothesis, that that is "confusing" to our neural circuits

00:05:44.740 | in a way that doesn't match up well with our thermodynamic requirements of how much we're

00:05:50.620 | burning versus how much we need to eat.

00:05:52.780 | Whereas when I eat a piece of steak and a vegetable, I actually want less carbohydrate

00:05:59.100 | afterwards.

00:06:00.100 | If I eat the carbohydrate first, for me, it's difficult because I love the taste of carbohydrates,

00:06:03.940 | especially when they're combined with fat.

00:06:05.540 | But there seems to be an easier time regulating food intake when people step back and say,

00:06:11.220 | "I'm going to consume minimally processed whole foods."

00:06:15.060 | And I'm guessing it's not just because they're trying to be healthier, that might be what

00:06:19.660 | stimulates the shift, but that the brain starts to learn the relationship between food volume,

00:06:25.900 | smell, taste, what these things look like, and satiation at the level of, "Oh, that's

00:06:31.980 | enough amino acids because I had a piece of fish, so maybe I don't need to consume as

00:06:35.300 | much of some other things."

00:06:36.340 | Or the vegetables provide volume and fiber, and often vegetables can taste really delicious

00:06:41.580 | too.

00:06:42.580 | So that there's a linking of nutrients, calories, and taste in a way that's more appropriately

00:06:48.100 | matched to the energetic demands of the organism, in this case, us humans, that highly processed

00:06:54.980 | foods bypass.

00:06:56.220 | Now, I realize that was long-winded and forgive me, but my audience is used to that.

00:07:02.340 | Whenever I'm trying to table something for, no pun intended, for discussion that I would

00:07:07.180 | like to think can at least stimulate some additional thinking about a landscape, in

00:07:11.660 | this case, nutrition and feeding behavior, that for a lot of people is just really confusing.

00:07:16.860 | And here's why.

00:07:17.860 | And this is the last thing I'll say.

00:07:18.860 | I have several friends who have been very overweight their entire lives, for whom the

00:07:24.940 | following diet has worked exceptionally well.

00:07:28.460 | I'm not a diet coach.

00:07:29.460 | I'm not a nutritionist.

00:07:30.460 | I don't pretend to be one.

00:07:32.020 | I say eat proteins like meat, fish, eggs, vegetables, and fruit, and do that for a couple

00:07:39.860 | of months, and then add back in starches as you see fit based on your food intake.

00:07:45.340 | And without fail, they all lose a ton of weight.

00:07:48.300 | They're very happy with that.

00:07:50.060 | They add back in a minimum of starches, they keep the weight off, and they're also exercising,

00:07:56.660 | but not more than they were before in most cases.

00:07:59.360 | And I don't think that it's meat or fish or vegetables per se.

00:08:02.860 | I think it's that they finally develop an appreciation for what different foods have

00:08:07.540 | in terms of what they actually need.

00:08:10.400 | And without fail, they all say, "Oh, you know, I went to this party and I had a piece

00:08:14.400 | of cake and it didn't taste good to me after three or four bites."

00:08:17.480 | So that's interesting too.

00:08:18.820 | So I just would like your thoughts on this.

00:08:20.240 | We're not defining any new diets.

00:08:21.600 | I don't sell any diets.

00:08:22.880 | I don't do any of that.

00:08:24.100 | But I find it amazing that when people start eating minimally processed whole foods, I

00:08:29.260 | have to assume that their brain changes as it relates to appetite, craving, and just

00:08:33.480 | kind of an unconscious understanding about what food is providing them or not.

00:08:38.140 | And that highly processed foods basically bypass all of this and just get you to consume

00:08:42.860 | more, perhaps in hopes of getting something that you probably aren't getting at all or

00:08:48.600 | that you need to consume a lot of this food in order to get.

00:08:51.500 | There are several interesting ideas there.

00:08:54.100 | So there's two that come to mind just thinking about what you just said.

00:08:57.380 | So the one is the idea of what's going on when these people consume simpler diets, more

00:09:02.940 | of whole foods.

00:09:04.620 | And one thing I think that's very likely going on is this phenomenon of sensory-specific

00:09:10.540 | satiety as being engaged.

00:09:12.380 | And so sensory-specific satiety is just the idea that as you expose yourself repeatedly

00:09:17.980 | to a certain flavor or taste, you basically lose appetite for that.

00:09:23.240 | You get specific loss of appetite for that flavor or taste.

00:09:26.340 | This is why, as you said, basically if you start off eating the protein, after a while

00:09:29.740 | you're like, "I don't want any more salmon, but I would like some carbohydrates now,"

00:09:32.540 | because you have this sensory-specific satiety.

00:09:35.060 | And so it's well known, actually, that if you simplify your diet, make your diet really

00:09:39.620 | simple, so there's just a few things, the sensory-specific satiety alone can cause you

00:09:43.840 | to eat less, basically, because there's just less variety in your diet and you don't want

00:09:47.860 | to eat more of that same thing.

00:09:49.240 | And so I think a lot of diets, actually, it's not about the specific macronutrient or the

00:09:53.740 | specific food, it's just that they're reducing the variety in the diet.

00:09:58.060 | Eventually you just get sick of eating the same thing.

00:10:00.980 | And the thought behind that idea is that it's important evolutionarily so that you eat a

00:10:05.100 | diverse diet.

00:10:06.100 | It's the reason, probably, that you want sweets after you've eaten a savory meal and so on.

00:10:10.100 | A second idea, though, that comes to mind is just, as you mentioned, this idea of learning.

00:10:14.620 | And so much about our preferences for food, they're not innate, they're driven by learning.

00:10:20.740 | And so there are some things that are innate.

00:10:22.500 | So if you put sugar on a baby's tongue, it'll smile, indicating that it likes it.

00:10:27.740 | And if you put something bitter, it'll frown.

00:10:30.340 | And a rat will do the same thing, a neonate rat.

00:10:33.420 | But most of flavor and the perception of food is not just sweet or bitter, it's this much

00:10:39.540 | more complex sensation that involves smells, it involves taste, and then it involves how

00:10:44.660 | those tastes and smells interact with the post-ingestive effects of the nutrients.

00:10:49.660 | So the sensing of those nutrients in your stomach and in your intestine, primarily in

00:10:54.100 | your intestine, are thought to then feed back and then change your preference for these

00:10:58.340 | foods.

00:10:59.340 | And so there's lots of examples of this that you can just imagine from everyday experience.

00:11:02.440 | Most people, the first time they had a beer or the first time they had a glass of coffee,

00:11:05.420 | found it repulsive, right?

00:11:06.700 | Because it's extremely bitter.

00:11:08.340 | But then we come to crave these things because we know what they do to our body, we like

00:11:11.460 | what they do to our body.

00:11:12.460 | And that doesn't just make us take them like they're medicine, we actually somehow change

00:11:16.140 | our very perception of how that flavor is.

00:11:18.060 | We actually come to savor that flavor we previously found disgusting.

00:11:21.100 | And it's because our sensation of whether something's good or bad depends on our internal

00:11:26.820 | state.

00:11:27.820 | And so it's an interesting idea, perhaps if these ultra-processed foods that have so many

00:11:31.580 | different ingredients and such an unnatural combination, perhaps this process of learning

00:11:36.660 | about the nutrient content of different foods and flavors becomes impaired because it's

00:11:42.620 | just the brain is not used, the brain's used to saying, this is a piece of chicken and

00:11:45.780 | this is primarily protein.

00:11:47.340 | And so I can gauge from this flavor, I can connect this flavor to an amino acid content,

00:11:51.700 | but something that's so diverse, it might be harder to do.

00:11:55.400 | - And isn't it the case that the neurons in the gut and the hormones that are produced

00:12:01.580 | by the gut as we digest food, and that the neurons in the brain that control appetite

00:12:07.060 | and feeding have to be tuned to macronutrient content, because those are the primary colors

00:12:15.220 | of nutrients and nutrients are the way in which we can persist on a day-to-day basis,

00:12:22.060 | right?

00:12:23.060 | I mean, I'm not trying to sound more sophisticated where simpler terms would suffice.

00:12:26.260 | What I'm basically saying is that the neurons in our brains that control these behaviors,

00:12:31.460 | both eating and cessation of eating an ingredient or an entire meal, can't be tuned to a particular

00:12:37.740 | food product or to chicken or to an egg or to a steak or to lentils, but rather to amino

00:12:46.220 | acid content, essential amino acid content in particular, essential fatty acids.

00:12:50.620 | And in the case of carbohydrate, whatever is going to replace whatever glycogen we might

00:12:54.140 | have depleted, right?

00:12:55.140 | I mean, like if we really break it down into biology, eating is for a purpose.

00:12:59.580 | And my understanding is that the purpose of eating is to replace those things as needed

00:13:05.540 | rather than to, you know, taste savory or taste, you know-

00:13:11.660 | Absolutely.

00:13:12.660 | Absolutely.

00:13:13.660 | Absolutely.

00:13:14.660 | Those are just, those sensory cues are just markers that tell the brain what might be

00:13:17.060 | in that substance.

00:13:18.060 | Thank you for tuning in to the Huberman Lab Clips channel.

00:13:21.260 | If you enjoyed the clip that you just viewed, please check out the full-length episode by

00:13:25.140 | clicking here.

00:13:26.140 | [BLANK_AUDIO]

Why Ultra-Processed Foods Cause Weight Gain

Chapters