Monday, October 5, 2015

That Time I Ate Most of a Large Pizza in One Sitting

Two weeks ago, I had a brush with Extreme Eating.  My experience illustrates some important principles of how the brain regulates appetite and body fatness-- and how it reacts to calorie-dense, highly rewarding foods.

Yes, it's true.  I stuffed my face with pizza.  And you know what else?  It was just what I needed at that moment.  Let me explain.

I recently went on an 11-day cycle touring trip with my wife, during which we rode and camped our way through broad swaths of Washington and Northwest Oregon.  We carried all our gear on our bikes, and the riding was often hard due to long days, steep hills, and loose gravel trails.

If you've ever been on an extended bike touring or backpacking trip, you know how much you need to eat to maintain your performance.  On this particular trip, I had the misfortune of catching a gastrointestinal bug that cut my appetite for several days.  As we continued on our trip and my body's calorie stores declined, my energy levels began to flag.  My legs became increasingly tired, and I had to start walking up hills that I would normally be able to handle.

I knew I had to replenish my body's calorie stores as quickly as possible, and to do that, I'd need to deploy the world's most powerful tool for putting calories into bodies: junk food.  And that's what I did.  My appetite started to return when we reached Cascade Locks, Washington, and we stopped in to a pizzeria for lunch.  We ordered a 15" pizza, which arrived with an absurdly thick layer of toppings and cheese.  Then, I proceeded to devour about two-thirds of it.  I estimate I ate about 2,200 Calories.

The most interesting thing, for our purposes, is that I was able to eat that much pizza in the first place!  Normally, my appetite would stop me after about 3-4 slices, and eating more than that would be uncomfortable.  But I ate twice that amount without any discomfort, hopped on my bike, and rode off feeling energized.  How is that possible?  The answer illustrates some key principles about how the brain regulates appetite and body fatness.

How it works

Since energy is such a critical part of survival and reproduction, the brain regulation of body energy is highly evolved and very complex, but we can roughly divide it into two systems (1):

  1. A system that regulates food intake on a meal-to-meal basis.  This is the satiety system, and it's centered primarily in the brainstem (particularly the nucleus tractus solitarius).
  2. A system that directly regulates body fat levels.  This is the energy homeostasis system, and it's centered primarily in the hypothalamus (multiple nuclei).  

The energy homeostasis system measures the size of body fat stores, primarily using the fat-secreted hormone leptin.  If your body fat stores begin to decline, the system kicks in to try to restore the lost fat (this is a key reason why weight loss is so difficult and often fleeting).  It does this by decreasing the amount of energy the body expends to some degree, but primarily by increasing appetite and the overall drive to eat food.  It particularly enhances the drive to eat calorie-dense foods like pizza that are highly effective at increasing body fat levels.

The satiety system receives a variety of signals from your stomach and small intestine that inform it of what you've just eaten.  At that point, your brain knows the volume of what you just ate, as well as its calorie density, and its content of fat, protein, and carbohydrate.  It integrates those signals together, and gradually reduces your motivation to eat as you take each additional bite.  This is accompanied by a conscious feeling of fullness.

These two systems interact with one another extensively.  Probably the most important way in which they interact is that the energy homeostasis system sets the gain on the satiety system.  In other words, if your fat stores are depleted, your energy homeostasis system tells your satiety system to become less sensitive to the signals it's receiving from the digestive tract.  This means it takes more food than usual to feel full-- sometimes, much more.

And that's exactly what happened to me.  My fat stores were depleted, and my energy homeostasis system knew it.  It sent a signal to my satiety system, instructing it to delay the satiety signal substantially so I could stuff my face and quickly make up the calorie shortfall.  It made me particularly attracted to calorie-dense junk food, the most effective way to put calories into bodies.

You might feel like your stomach is full after you eat a big meal, but it usually isn't.  The human stomach has a remarkable capacity to stretch and accommodate absurd amounts of food.  That sensation of impending stomach rupture doesn't actually come from your stomach-- it comes from your brain.  It's a highly processed signal that your brain produces by interpreting signals from your stomach in the context of your body's current energy stores.

The human brain is naturally attracted to foods that deliver large, concentrated loads of easily digested calories.  That's because eating those types of foods whenever possible kept our ancestors alive and making babies for millions of years under extremely rugged circumstances.  In certain atypical contexts, such as the one I was in during my bike trip, those foods are literally good for you.  But that same ability to deliver calories so effectively becomes a liability when it's exaggerated to an unnatural degree by advanced food technology, readily available all the time, and placed in the context of a population that lives a pampered lifestyle.  Our food technology and lifestyles have evolved, but the hard-wired brain circuitry that sets our appetite and our food affinities hasn't.

And that's why I only let myself eat pizza a few times per year.

Stay tuned for a much deeper exploration of these subjects in my upcoming book, The Hungry Brain.  It should be on shelves in late 2016.


Paul Jaminet said...

Great news about the book!

Chris McFarland said...

I can't even imagine how an extended bike trip is possible with a gastrointestinal bug :) Impressive dedication.

Great news about a pending book.

Ryan Bergren said...

Great article as always. Looking forward to the book

Peaceful Pony said...

Late-2016? Oh man. Was hoping a lot sooner!

Unknown said...

Looking forward to the Book Stephen!

Stephan Guyenet said...

Hi Folks,

Thanks for your enthusiasm about the book. I'm actually almost done writing it, but it takes a long time for a finished draft to turn into a physical book on the shelf. I'm super excited about it though. So far I've interviewed more than three dozen leading researchers.

Thorgal Aegirsson said...

Hi Stephan,

I recognize what you describe in my own experience.
What I would like to know a little more about is the concept of a body mass / fat setpoint. The thing is, I had been losing quite a lot of weight for the last 3 years, at least for my corpulence and body height (nothing dramatic like 150lbs, more like 30-35lbs). 3 months ago, I went through a rough few weeks due to a change of home address. I lost some more weight (~ 8lbs). After 2-3 weeks, my physical activity decreased substantially but my weight has not moved back up since. I eat regular meals (~ 3 x a day), mostly natural whole foods (plenty of carbs, whatever protein comes with them + occasional eggs / cheese / meat or fish - not a daily thing though, and a little fat around the corners for cooking). Sometimes I will have pizza or ice-cream, but it is a rather rare occurrence. If what you say is true, I should have regained the lost weight but I can't seem to overeat as I used to, prior to 2012, I was probably indulging too much in calorie dense junk foods, it's like I am not interested any longer.

Care to explain how this works ?

glib said...

I have done several of those trips, although always between 3 and 7 days (but I have done canoeing trips of 12 days or more), and I know that you have to eat 5-6000 kcal per day if you want to go 60-100 miles in rolling terrain. On the first trip with my wife, we were up in some mountains in France, and I screamed that I had to eat. She told me she had never seen me like that. I ate and became normal again. These trips are quite the metabolic kick, you go through your fat quite a bit, and back then I would go also through some toxins that were stored in the fat. Nowadays when I go through my fat (I worked in Japan for two months this summer, I lost 12 lbs) I notice no ill effects.

Mito Pedersen said...

I'm experiencing recovery from an eating disorder (years and years of undereating, many of them paleo and then perfect health diet) and am having extreme hunger as you describe. My sense of hunger/satiety is completely off. Youreatopia is a cool place (Extreme hunger II) to learn about it.

Sunny said...

Congrats on the trip. Re pizza- sounds like a binge to me. I am surprised or maybe more accurately deflated to consider that with such vast and indepth study of nutrition, the mammoth pizza is chosen as the solution.

Stephan Guyenet said...

Hi Thorgal,

Two things may explain your experience. First, the "setpoint" can change, and one of the things that changes it best is improving the diet (although it isn't necessarily a magic bullet). You didn't say how your diet changed (if at all) during your weight loss, but that is one possible explanation.

Second, how the energy homeostasis system responds can differ between individuals. Some people defend their weight extremely tightly and even a single pound of fat loss will trigger a vigorous response. In other people the energy homeostasis system defends weight more loosely, and it may take a rather large weight loss to trigger a response. Not surprisingly, the latter type of person has an easier time losing weight.

Hi glib,

Thanks for sharing your experience.

Hi Sunny,

I suppose it depends on how you define the word "binge". Does it qualify as a binge if it's constructive?

I acknowledge that pizza is a blunt tool, but it got the job done!

To be clear, I rarely eat that type of food. 90 percent of what I eat, I make from scratch in my own kitchen. And actually I grow a lot of it myself too. But I'm not afraid to indulge every now and then.

Jennifer Haden said...

Can't wait for your book to come out.

I have a question for you Stephen. I see alot about how carbs aren't bad for you and that combined with a healthy lifestyle and exercise they are beneficial. But one population that always get's disregarded for the most part is disabled or chronically ill people that can't exercise. Do you believe that carb's, either moderate or higher carb, would still be fine for someone that is forced to be sedentary? Is it still all down to calories at the end of the day and not so much macro-nutrients?

RLL said...

The diabetics amongst us would be curious what your blood sugars were doing during all of this. You 'normals' ought occasionally meter them in these extreme situations. I understand readings in the 60s are common, and after a huge meal a brief foray as high as 160, dropping rapidly over a few hours. You may already have done this.

Tim said...

I certainly sympathize with your experience, Stephan! However...

As an European I just have to protest against the identification of pizza with the American junk-food interpretation thereof (i.e. a thick and fluffy dough to hold an even thicker topping with obscene amounts of fat-dripping chese ;). Anybody who has ever tasted an original pizza Marinara on Sicily (a thin, crispy flat bread fragant from the wood stove, topped with nothing but a sauce of ripe tomatoes, garlic, herbs and olive oil - and perhaps a few olives or anchovies) - or even a Margherita topped with fresh basil and some mild Buffalo mozarella (which is not only much lower in fat than hard cheese but becomes so liquid when baked that it would be physically impossible to fit even half the amount on the same diameter as it is standard for an American "pizza"). Of course traditional Italian cuisine has much more to offer than pizza, both culinary and healthwise - but even the original pizza is a much better and less carolic food than what modern fast food made out of it.

Stephan Guyenet said...

Hi Jennifer,

I don't think carbohydrates are inherently fattening in general. However, someone who can't exercise and needs weight control measures might consider either a very-low-fat or a very-low-carb diet, both of which are useful for appetite and weight control. Personally, if I was faced with the choice, I'd go the low-fat route, but I think the response can vary by individual.

Hi Tim,

I've had pizza in Italy and I quite enjoyed it, but I also quite enjoy a well-made American-style pizza. I'm not talking about Pizza Hut, but a good pizzeria.

Sylvain Martel said...

Thank you Stephan to help me understand that when I had four yogourt in one sitting, after a couple of days fasting, and coul hardly stop, my brain was responding correctly. What I understand, from your saying is that when we are eating less calories than our resting daily metabolic rate, it is absolutely normal to have a strong hunger reaction, especially when we are not very well keto adapted.

Am I correct?

Sylain M

Roland Denzel said...

Can't wait for the book!

I recommend a book launch party at Delancey, which is the best place to overeat pizza in the Seattle area.

Anne said...

Hi Stephan,

My apologies in advance for the long post... I have struggled with weight my entire life, and the more I learn about the physiological aspects (e.g., leptin resistance) involved with satiety signals, the more convinced I am that my struggles are related to those factors as well as genetics. Some pertinent background info: I am a 31-year-old female. My TSH and insulin levels fall within the normal range. I have no medical conditions and do not take any medications. I have gained and lost significant amounts of weight numerous times, and each time, I've gained more weight than before at a faster rate. None of my weight issues are explained by eating disorders (e.g., bulimia nervosa, binge eating disorder, etc.) or related to emotional distress. Over five years ago, my weight peaked and I lost over 70 pounds (bringing my weight from obese down to a normal BMI range) over the course of about two years. Since that time, I have primarily maintained most of that weight loss, although there have still been periods of significant (i.e., 10-15 pound) weight gains and losses. For the past five years, my diet has consisted primarily of whole foods. I am highly active (300-400 minutes/week of high intensity physical activity). I do my best to limit food intake to appropriate portions; however, this remains my biggest obstacle. In fact, I RARELY EVER FEEL FULL, NO MATTER WHAT. I have been this way my entire life. If I allowed myself, I could eat an entire pizza every day, and my body does not feel full. I drink at least 1/2 my body weight in ounces of water, eat fiber rich foods, etc; yet, I almost never feel satisfied; thus, it is always a tremendous battle to stop eating. The amount of effort I put forth to simply try to maintain a healthy weight is beyond taxing and I have reached a point where any further weight loss has been unachievable (I would like to lose 10-15 pounds, which is still well within a healthy BMI range). Is there anything you can suggest I do? I have heard of leptin supplements, but I am skeptical of these (and wouldn't even know where to begin to find a good one) . I would be so appreciative of any guidance you can offer. Thank you so much for your time!

Thomas Hemming Larsen said...

Hi Stephan,

Thanks a lot for sharing this experience. I feel I can relate to it. I have a history of anorexia but have regained my weight. I'm still very lean though. My weight has been stable for months now. I still mentally have problems with eating consistently despite being active and working out hence needing the calories. I often have cravings for fat or foods like cheese and nuts (some times thick textures too).
Am I experiencing what you're describing? That my brain is saying that it needs more calories? Often I'll fill myself with low calorie, high fiber foods without feeling satiated, is that the same mechanism? The brain senses that its not a lot of calories so it tells me to eat more?

Honey Razwell said...

The brain indeed regulates weight and this largely involuntarily regulation dominates. It is amazing. The fitness industry has a foundation of lies. Our conscious efforts are limited if the body says "no."

Some people can indeed eat lots of pizza and not gain much bodily matter or fat matter specifically.

One thing I have to note to everybody and it is something I should have noted years ago:

Energy is an extremely difficult concept to understand and it is often misused by even medical doctors. It was an extremely difficult concept to understand for Feynman himself. Where does leave the rest of us?

Energy is not a thing - at all. There is no caloric energy whatsoever being turned into or converted into fat matter or any other body matter of any sort. It is impossible for humans to convert energy into matter- stuff. Our bodily matter ( fat, muscle, organ bone etc.) is not built from calories. Our matter comes from OTHER matter. Calories are NOT what puts body fat on us at all. Heat energy cannot be turned in to matter.

The caloric hypothesis is wrong in principle, as energy cannot in anyway be turned into matter in a human or an animal. Energy is an abstract concept. It is not a "thing" at all, it is a property of a thing.

While the insulin hypothesis is very limited and too simplistic, the caloric model ALSO posits something very wrong in principle.

Best wishes,

John said...

Pizza is my favorite food. When I eat it I notice something very fascinating - I tend to feel hungrier as I eat until I've finished the entire pizza, and then I progressively feel more and more full for a few hours. I'm talking large 18" pizzas that are probably in the 5k+ calorie neighborhood. In one sitting.

I'll feel hot all night, and for a large portion of the following day, and will definitely notice appetite suppression for about 24 hours.

I've been 5'9" and 155lbs for about a year, and 165-170lbs for about 5 years before that (deliberately cut down Leangains style - super high protein, tons of veggies - 0.5 - 1lb/week loss without a single craving).

I am sort of a bottomless pit - I can usually eat way beyond a point I know consciously is "enough" food. If I'm not counting calories, I find the most effective weight management tool for me is fasting until dinner on the days I know I've got a big dinner ahead, and being very deliberate with my food choices the next day. If I go to a restaurant, I know its going to involve bread bowl decimation, appetizer, entree, and dessert, all regardless of whether I've eaten earlier in the day. Perhaps gorging myself somewhat regularly is not the healthiest behavior but I haven't had a "I am CRAVING x" sensation in a long long time, and have stayed lean, strong, and healthy for a long time now.

Stephan Guyenet said...

Hi John,

The French have a saying, "l'appetit vient en mangeant": appetite develops as you eat. Basically, sensory cues (smell, appearance, flavor) of foods the brain values highly cause the brain to take the brakes off your normal satiety mechanisms. Junk food is a confluence of food properties the brain is hard-wired to value. The eating motivation this food triggers is probably unnaturally strong relative to what our distant ancestors would have experienced with the simple food that was available. We've used technology to optimize our food to match our innate food preferences, but we've done it a little too well. I'll be discussing this in detail in my upcoming book.

Anyway, glad you've found a way to mange it constructively.