Essentials: Healthy Eating & Eating Disorders - Anorexia, Bulimia, Binging

0:00Welcome to Huberman Lab Essentials, where we revisit past episodes for the most potent and actionable science -based tools for mental health, physical health, and performance. I'm Andrew Huberman and I'm a professor of neurobiology and ophthalmology at Stanford School of Medicine. Today we are going to talk all about healthy and disordered eating. And indeed we are going to talk about clinical eating disorders such as anorexia, bulimia, and binge eating disorder, as well as some other related eating disorders. However, before we get into this material, I want to emphasize that today's discussion will include what it is to have a healthy relationship with food.

0:41We are going to talk about metabolism, we are going to talk about how eating frequency and what one eats influences things like appetite and satiety, as well as whether or not we have a healthy psychological relationship to food and our body weight and so -called body composition, the ratio of muscle to fat to bone, etc. So as we march into this conversation, I like to share with you some interesting and what I believe are important findings in the realm of nutrition and human behavior. I know these days many people are excited about or curious about so -called intermittent fasting. Intermittent fasting is, as the name implies, simply restricting one's feeding behavior, eating to a particular phase of the 24 hour or so -called circadian cycle.

1:34Other forms of intermittent fasting involve not eating for extended periods of time, for entire days or some people will extend to two days or three days, typically and hopefully they will drink water during those times, sometimes referred to as water fasting, which means that they are eating. They are ingesting fluids and hopefully they are ingesting electrolytes such as salt, potassium and magnesium as well, because while one can survive for some period of time without ingesting calories, it is extremely important to continue to ingest plenty of fluids and electrolytes. The reason for that is that the neurons of your brain and body, the control of your movements, your thoughts, clarity of thinking in general, etc., is critically dependent on the presence of adequate levels of sodium, potassium and magnesium.

2:25The electrolytes and that's because neurons can only be electrically active by way of movement of particular ions, which include things like sodium, potassium and magnesium. So without those, you can't think, you can't function and it actually can be quite dangerous. So why all the excitement about intermittent fasting? Well, a lot of the excitement relates to work that was done by a former colleague of mine down at the Salk Institute for Biological Studies in San Diego named Sachin Panda. Sachin's lab identified some very important and impactful health benefits of restricting one's feeding window to particular times within the 24 hour cycle, or even to having extended fasts that go for a day or two days or maybe even three days.

3:08What they saw was an improvement in liver enzymes, an improvement in insulin sensitivity, which is something that is good. It means that you can utilize the calories and the blood sugar that you happen to have. Being insulin insensitive is not good and is actually a form of diabetes. What Sachin's lab and subsequently other lab showed was that restricting one's feeding window to anywhere from four to eight or even 12 hours during each 24 hour cycle was beneficial in mice and some studies in humans have also shown that it can be beneficial for various health parameters. However, the excitement about intermittent fasting seems to be related to the foundational truth about metabolism and weight loss and weight maintenance and weight gain, which is that regardless of whether or not you intermittent fast or whether or not you eat small meals all day long or you eat one meal in the evening and snack up until then it really doesn't matter in the sense that the calories that you inject.

4:17Rest from whatever source are going to be filtered through the calories that you burn by a way of exercise, basal metabolic rate, which is just the calories that you happen to burn just being alive and thinking and breathing and your heart beating, etc. And the reason why many people prefer intermittent fasting to other forms of let's just call it what it is diet or nutritional framework is that many people find it easier to not eat than to limit their portion size. And here I'm not talking necessarily about eating disorders. I'm talking about the general population. So why are we talking about this and in particular why are we talking about this during an episode that includes a discussion about eating disorders.

5:03The reason is nobody, not the government, no nutritionists, no individual, no matter how knowledgeable they are about food and nutrition and food intake can define the best plan for eating for any one individual. I'm going to repeat that. Nobody knows what truly healthy eating is. We only know the measurements we can take liver enzymes, bloodlippered profiles, body weight, athletic performance, mental performance, whether or not you're cranky all day, whether or not you're feeling relaxed. Nobody knows how to define these and these have strong cultural and familial and sociosuscidal influence.

5:47So if you hang out with people that intermittent fast all day, that will seem normal. If you spend time with people that have never heard of intermittent fasting, intermittent fasting is going to seem very abnormal. Now we are going to talk about eating disorders that really fall into the category of clinically diagnosable eating disorders for which there's actually serious health hazards and even the serious risk of death. There are clear criteria in the psychiatric and psychological communities to define things like anorexia, bulimia, binge eating disorder, all of which we will talk about. Because we have that discussion, I want to emphasize that self -diagnosis can be both a terrific but also a very precarious thing.

6:29There's always a temptation as one learns about the symptomology of a given disorder, doesn't really matter what the disorder is, to ask the question, well, do I have that? Does so -and -so that I know have that? It's tempting to diagnose them and -or ourselves as either having or not having a particular disorder. However, diagnoses really need to be carried out by people who are trained in that particular field and that have deep expertise in recognizing the symptomology, including some of the more subtle symptomology of eating disorders. So if any of the symptoms resonate with you by way of you thinking that you have this particular disorder or someone that you know has this disorder, I would take that seriously.

7:11But I would take that information to a qualified healthcare professional that could diagnose or rule out any of these possible disorders. I'd like to take a quick break and acknowledge one of our sponsors, Element. Element is an electrolyte drink that has everything you need and nothing you don't. That means the electrolytes, sodium, magnesium, and potassium in the correct amounts, but no sugar. Proper hydration is critical for optimal brain and body function. Even a slight degree of dehydration can diminish cognitive and physical performance. It's also important that you get adequate electrolytes.

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8:51So what is an eating disorder? Well, we have to take a step back and confess to the fact that every society, every culture, every family, and every individual has a different relationship to food. Eating disorders, however, have particular criteria that allow us to define them and to think about different modes of treatment as it relates to the particular symptoms, in particular, the psychological and biological symptoms of those disorders. What are the major eating disorders? Anorexia nervosa, most commonly referred to as anorexia, is perhaps the most prevalent and the most dangerous of all eating disorders.

9:36In fact, anorexia is the most dangerous psychiatric disorder of all, even more than depression. The probability of death for untreated anorexia is very high, and sadly, the prevalence of anorexia is very high. If you look it up online or you talk to a qualified professional, it's essentially a failure to eat enough to maintain a healthy weight. You can see all sorts of very troubling symptoms of somebody who's been anorexic for some period of time, a general loss of muscle mass, because they're ingesting fewer calories than they burn. They will have a low heart rate. This is the body and brain's attempt to lower energy output.

10:20They will have low blood pressure. They will sometimes have symptoms like fainting, loss of bone density, osteoporosis, loss of periods in girls and women, and all sorts of disrupted gut and immune functions. There are just tons of terrible symptoms of anorexia that really place the anorexic into a very risky state, which is why mortality from anorexia gone untreated is extremely high. Now, one of the misconceptions about anorexia is that it stems from an overemphasis on perfectionism, or that because of all the images in social media and in advertising of extremely thin and fit or muscular people that individuals are looking at themselves and comparing themselves to those images and thinking that they don't match up and developing anorexia.

11:18That turns out to not be the case. If you look at the prevalence or the rates of anorexia in the last 10 years or 20 years, and you compare that to when anorexia was first identified, which was in the 1600s, and perhaps even earlier, what you find is that rates of anorexia are not going up. Classically defined anorexia has existed as essentially the same prevalence for the last 100, 200, 300, and 400 years, which is incredible and really speaks to the likelihood that there's a strong biological contribution to what we call anorexia neurosa. Anorexia neurosa is extremely common. It's anywhere from 1 to 2 % of women.

12:03And the typical onset is in adolescence, close to puberty, but it can show up later in life as well. In fact, the identification and diagnosis of anorexia tends to be in the early 20s. But if you look back at the history of those individuals, there were typically signs of anorexia that stem back into their early teens or maybe even before that. Now, of course, men can be anorexic as well, but anorexia neurosa does seem to occur at 10 times the rate in women and young girls than it does in men and young boys. So what is hunger and what is satiety? Satiety, of course, being sated or feeling like we've had enough food.

12:45I want to remind people of the basic mechanisms by which the brain and body communicate. The body is communicating two types of information to the brain on a regular basis, but in particular around feeding. And those two types of information are mechanical information and chemical information. When your stomach is full, it sends signals to your brain that are purely based on this mechanical fullness. That's nothing to do with nutrients that says, I'm full. And therefore, don't be as hungry. Don't motivate to find or ingest food. Whereas when our gut is empty, even if we have plenty of nutrients or plenty of body fat stores, we tend to focus on food a bit more.

13:28So volume and mechanical influences have a profound effect on how we think and what we consider doing or not doing. Likewise, chemical effects. When we ingest food, our blood glucose goes up. That information is signal to the brain via neuronal pathways and hormonal pathways. And in particular, there are neurons within our gut that signal to areas of our brainstem that are involved in satiety in our sense of having enough that there's food in our system. So that's chemical information. So how are hunger and feeding and satiety regulated by way of mechanical and chemical signaling. You have, I have, we all have neurons in our hypothalamus that trigger eating and neurons that trigger cessation or stopping of eating your hypothalamus at the base of your forebrains.

14:20It's more or less above the roof of your mouth. The hypothalamus contains lots of different kinds of neurons, including neurons that stimulate sexual activity and desire, regulate your body temperature and control appetite and ceasing of eating an appetite. There are two types of neurons within a particular area of your hypothalamus that are relevant here. There are the so -called POMC neurons, okay? Proopioid -Malana -Corton neurons that tend to act as more of a break on appetite by way of another hormone called melanocytes stimulating hormone. And you have a class of neurons called the AGRP neurons.

15:00The AGRP neurons are the ones that stimulate feeding. And they create a sort of anxiety or excitement about food. If you eliminate or kill these neurons, which has been done in experimental mouse models in the laboratory, but also there are humans that have lesions or neurotoxic effects on these AGRP neurons. And what you find is that they don't want to eat. They have no appetite for food whatsoever. Whereas if you stimulate these AGRP neurons, they're more in humans that have, say, a small tumor near these AGRP neurons. They become hyperfagic. They will eat to the point of bursting. Now, there are signals coming back from the body to inform the brain about presence of different levels of nutrients.

15:41And that generally comes from three sources. First of all, is body fat. The more body fat we have, the more we secrete a hormone called leptin, LAPTIN, leptin from body fat. Leptin goes to the brain and suppresses appetite. Not incidentally, leptin signaling is disrupted in people that have bulimia and obesity and certain forms of binge eating disorder. The body fat is doing something else really interesting that relates to anorexia. When there's sufficient levels of body fat and leptin circulating in the blood, and that leptin signal gets to the brain, the hypothalamus and the pituitary gland register that signal.

16:23And in a completely subconscious way, trigger the deployment of eggs in females and the production of sperm and males. So when body fat stores are very low, the reason why periods shut off or sperm production is reduced or even shut off is because there's not enough leptin getting to the hypothalamus and to the pituitary. And they shut off the signals, the hormones, things like conatotropin releasing hormone, luteinizing hormone, follicle stimulating hormone that travel to the overyear to the testes and cause the overyear testes to ovulate or to produce more sperm. So you've got two categories of neurons, one that acts as an accelerator, the AGRP neuron saying eat, eat, and gets you excited to eat.

17:07And then you have a category of neurons, the POMOC neurons that are suppressing hunger, they're acting like a break. And the body is informing the brain all the time about the status of the body and whether or not it needs more food. So you might ask why is it that people who are overweight and have a lot of body fat, why they would continue to eat a lot, seems like that just shouldn't happen. And from an evolutionary standpoint, it makes sense that we should eat as often as we can, as much as we can, and as fast as we can. There are circuits in the brain to reward eating often eating fast and cramming as much food into you as possible.

17:45Because from a purely evolutionary standpoint, food was scarce and seeking food was dangerous, whether or not it was from animal sources or not. And it's always been competitive. Every animal, including humans, has a hardwired circuit that we were born with that pays attention to how much food is available, how much we are getting now and how much we are likely to get in the future. And without going down the rabbit hole of arqueous nucleous biology, in two sentences you have a hypothalamic area called the arqueous nucleus. It's actually the area that houses these PMOC neurons and these other types of neurons that regulate hunger and satiety.

18:27And these neurons in the arqueous nucleus start getting active when we see food and think about food. And they drive hunger in a way that's responsive to what the food looks like, what it smells like, but also our prior history of interactions with that food. And it takes into account social context. What's the pathway? How does this work? Well, you can frame all of behavior, good decision making and bad decision making in a pretty simple box diagram model. We have knowledge of what we should do in one box. We should eat that, we should eat that, we should wait for dinner, we shouldn't wait for dinner.

19:07And then we have what we actually do in another box. In between those two boxes are two intervening forces and those intervening forces are critically important. Those intervening forces are homeostatic processes that regulate the balance of different systems in your body, hot and cold, awake or asleep. Dopamine and the desire to pursue things, serotonin and the desire to just relax and chill. So homeostatic processes and reward systems. And as we now move into discussion about anorexia and bulimia specifically, what you'll see is that anorexia and bulimia are not a breaking of the mindset of what one should do or shouldn't do.

19:53It's a disruption of these homeostatic and reward processes such that decision making is completely disrupted and in many cases is not available to the anorexic or bulimic. Now, I don't want to be abstract here. What I'm saying is that the person who starves themselves to the point where they might die and in some cases sadly do die, they can know perfectly well that their behavior is leading to bad outcomes and possibly even death. And yet they are not able to intervene unless they get particular clinical help because the homeostatic processes, the signals from the body and brain that say you need food, those aren't registering in the same way that they are for other individuals.

20:39And just as a little teaser of where we're headed, anorexics have a sort of switch that's been flipped such that their decision making is actually pretty darn good. It might even be better than yours in terms of evaluating food nutritional content, but their habits are disrupted. So they're not even consciously aware of the fact that they're making terrible and in some cases very dangerous food choices and turns out habits and the way that we build and break and rebuild new habits is one of the most effective treatments for anorexia. I'd like to take a quick break and acknowledge our sponsor, AG1.

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22:28As I've highlighted before on this podcast, omega -3 fish oil and vitamin D3K2 have been shown to help with everything from mood and brain health to heart health to healthy hormone status and much more. Again, that's drinkag1 .com slash uberman to get a free one month supply of omega -3 fish oil plus a bottle of vitamin D3 plus K2 with your subscription. So now let's talk about anorexia. This failure to consume enough energy such that the individual is at risk of death. And if not death, then severe metabolic disorders, lack of bone density, etc. A careful analysis through medical epidemiology has shown that you find anorexia even in cultures and societies where food is scarce.

23:10So that really speaks to biological mechanism. Typically anorexia starts in adolescence right around puberty. Puberty at a very broad level is the most significant and dramatic developmental step anyone goes through in their lifespan. The body changes, the brain changes, perceptions change, one's own self -perception changes, and most of those changes are driven by changes in circuitry within the hypothalamus. So neurons that are controlling the production of the so -called sex steroid hormones, things like testosterone estrogen and related hormones prolactin, etc. Those are all changing at very rapid rates.

23:47Let's look under the hood. Let's look at what's known about the neural circuitry and the sorts of perceptions and behaviors of the neural circuitry is driving in order to understand what they are truly suffering from at the level of cause. Not just symptoms. First of all, there's a challenge in studying anorexia because in anorexia what you're essentially studying is the absence of a behavior. It's very hard to study the absence of a behavior as opposed to a behavior. So they did some experiments with anorexics giving them a gallery of pictures of different foods and allowing those anorexic patients to arrange those foods according to preference about what they would select, about food nutrient content, about caloric content.

24:32And they essentially asked these anorexics to evaluate food. And in doing so, they were able to identify something that's very unique to anorexics at the level of their perception of food. Anorexics rather than being anxious in the presence of food have a hyper acuity, a hyper awareness of the fat content of foods, almost at the point of being sort of fat content savants. Now it's a well -known symptom of anorexia, especially young anorexics that they have kind of an obsession with food, caloric content, macronutrient ratios, meaning fat, protein, and carbohydrate ratios. They are actively avoiding high fat content foods, calorie -rich foods, and defaulting towards very low calorie foods if they have to eat.

25:21And that's very important because what that means is that we need to look at the areas of the brain that drive habit formation and habit execution. In the case of the anorexic, those habits are exactly the place where things start to go awry, and that drive this very dysfunctional under -eating behavior that sadly often leads to death or certainly bad medical outcomes. And it turns out that the brain areas associated with habit formation and execution are the best point of intervention. So you have reflexes, and you have neural processes that include what are called duration path and outcome type processes.

26:05A duration path outcome type process we can shorten with DPO. DPO is for all types of goal -related behaviors. So for instance, if you want to go to the grocery store and pick some stuff up and then head home, you're going to think duration, how long do I have? Okay, do I have 45 minutes to get to the store? How long does it take to get to the store? Path, which way am I going to drive there? Which way am I going to navigate through the grocery store? The first time I've ever had a customer out come was I able to get in and get the items I need and get home in time. Okay, DPO, duration path outcome.

26:37It's a very conscious process that requires decision making and it's reward -based. You use these DPO type processes in the short term to pick up groceries and pick a line at the grocery store and decide which trajectory to take home. And you use them for navigating long extended processes in life, trying to get a degree or raise children or get through a particularly challenging year, et cetera. So duration path outcome and that entire process relies on your forebrain, this prefrontal cortex. The prefrontal cortex is what allows you to take information from memory, combine it with information about what's happening in the present context, and then to direct your behavior, your speech, et cetera, toward particular outcomes.

27:25Reflexes on the other hand don't involve the prefrontal cortex in the same way. Habits and reflexes, like once you know how to walk, that doesn't rely on prefrontal cortex. It's subconscious as it's sometimes called, but basically you don't have to use the parts of the brain that are involved in duration path and outcome type analysis. But basically of a brain area and anorexia is have a brain area that's involved in evaluating and decision making around food and then another brain area that's involved in the reflexive consumption of particular foods and the reflexive avoidance of other foods.

27:58There are always homeostatic and reward systems influencing this kind of thing. Well, in the brain of the anorexic, it turns out that the reward systems have been attached to the execution of habits in a way that is unhealthy for body weight. But at least from a purely neural circuit perspective, the reward is now given, this chemical reward in the brain is given for avoiding particular foods and only approaching these very low calorie, low fat foods. So there really does seem to be a flip in the switch in the anorexic brain that rewards them internally. They feel good when they avoid certain foods and they approach others.