- How does the food reward system work? Why did it evolve?
- Why do certain flavors we don’t initially like become appealing over time?
- How does industrially processed food affect the food reward system?
- What’s the most effective diet used to make rats obese in a research setting? What does this tell us about human diet and weight regulation?
- Do we know why highly rewarding food increases the set point in some people but not in others?
- How does the food reward theory explain the effectiveness of popular fat loss diets?
- Does the food reward theory tell us anything about why traditional cultures are generally lean?
- What does cooking temperature have to do with health?
- Reader question: How does one lose fat?
- Reader question: What do I (Stephan) eat?
- Reader question: Why do many people gain fat with age, especially postmenopausal women?
Tuesday, May 24, 2011
Healthy Skeptic Podcast
Chris Kresser has just posted our recent interview/discussion on his blog The Healthy Skeptic. You can listen to it on Chris's blog here. The discussion mostly centered around body fat and food reward. I also answered a few reader questions. Here are some highlights:
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49 comments:
Love this! I still need to listen to the last 15 or so minutes, but wanted to make a quick comment before heading off for my workout.
Interesting how your suggestions (including your 4th stage) map to Tim Ferriss' Slow Carb diet (from his book 4 Hour Body).
He promotes his cheat day (once a week) as a way to avoid calorie-restricting hormone issues (like thyroid). But as he also promotes monotony on the 6 other days of the week, you could see how it could also affect food reward.
If you google 'v-diet' you will find an almost all liquid diet consisting of protein shakes that is used to achieve very low body fat percentages. It looks like it fits in well with your framework.
What I have in mind is doing a healthier 'paleo' version by drinking a shake of blended coconut milk, kale, sweet potatoes, and eggs 2-3 times a day. What are your thoughts on a liquid diet such as this compared with a solid-food diet to effectively achieve low body fat levels?
stephan:
much better presentation of your ideas! Don't dribble it out there.
The idea that the food reward system is overloading your leptin is powerful. Of course, that isn't true for everyone.
I've been thinking a more useful way to approach this is "Why are some people thin" rather than the other way around.
And a ensure/milkshake/muscle milk diet sounds disgusting.
"What does cooking temperature have to do with health?"
I've been wondering about this lately too, because it seems to be a trend with foodie blogs to roast as darkly as possible. Many times I'm squicked out by what I think looks burnt, but they're SO proud, eww. I'll stick with golden with a few brownish spots, no charred for me.
Stephan, this is was a good and persuasive explanation. It explains seeming paradoxes and contradictions.
A big sub-area I'm very curious about is calorie partitioning. We know that the body can do three things with "excess" calories: burn them (ie your energy levels increase), store as fat, or build muscle. And even under the "store as fat" category, the fat could primarily be sub-cutaneous or visceral/ectopic.
It strikes me that food reward causing increasing the set point sounds plausible as an evolved response to running into a surplus of nutritious foods. Basically, eat while you have the chance. Store the nutrients for later, when less nutritious fare may not be available.
But why store it around your liver vs on your butt? Or, why store it as fat vs building muscle? Or even why in some circumstances would the body say no, you need more energy, let's go burn it.
I wonder if calorie partitioning is related to food composition, or if it's "just" related to physical context, ie level of musculo-skeletal stress & exertion.
Put another way, is food reward only for gaining fat, or could food reward be used purposefully to gain muscle or energy?
Here's a summary of what Stephan said he eats (additions or corrections welcome):
Stephan eats foods that are less processed, processed in traditional ways and gently heated.
Breakfast: 1-2 medium potatoes with butter or palm oil, 1 gently cooked egg, sauerkraut or a raw carrot, a handful of almonds or hazelnuts. Or a sourdough buckwheat pancake instead of the potato.
Lunch: 1-2 microwaved potatoes, grassfed ground beef or lamb or chicken, cooked gently with greens & onions and without spices or salt but with herbs.
Dinner: Potatoes or sweet potatoes, beans or lentils (soaked 24 hours before cooking with seaweed) with 50/50 white & brown rice also soaked beforehand, fish, a salad with vinaigrette (or fresh vegetables), cow or goat dairy (usually fermented), almonds or hazelnuts, fruit, and sometimes a small glass of wine.
He drinks herbal tea, but has no caloric beverages or snacks between meals.
He estimates that he eats 50% carbs, 35% fat and 15% protein.
Thank you very much, Stargazey, I'm Spanish, I read English well but I don't understand spoken English. I have listened the podcast 20 times and I don't understand anything. I have translated this in Google. I would like other summaries of the podcast. Thanks.
Silly me! All these years I've been eating food I enjoy while wishing I was thinner!
@Peter, you're right! If I had to eat that stuff, I'd lose 100 pounds. And I don't weigh a whole lot more than 100 pounds!
Very interesting stuff, Stephan.
Some of the evidence you cite is very persuasive.
But I guess there are other problems besides the French. I'm not sure they don't remain a problem, because I still have problems seeing the distinction between a reward as behaviorist psychology means it and actually liking something. I don't know whether it's me or behaviorism.
But besides the French, what about people in India? There the food tastes; it's highly spiced. But I don't think Indians are generally obese.
The other cuisine that occurs to me is Chinese. That is spicy. The Chinese don't seem to be obese on the whole. True, what we know as Chinese food is what Chinese restaurateurs sell not what people eat in China. But I don't think their food is bland. It's also not generally cooked at low temperature. Woks get hot. The only reason food doesn't actually burn when people stir-fry is that they keep it in constant motion.
I don't mean to nitpick. I'm more than half convinced.
Stephan
As you may know, constitutionally lean people (ie very low fat set point) have been found to have higher BMR per kg of FFM than normal weight controls (coupled with lower leptin), consistent with the idea that having a naturally low fat set point should make you highly sensitive to the metabolically stimulating effects of leptin.
This implies that any intervention said to lower your body fat set point should allow you to lose weight while maintaining a normal metabolic rate. Do any of the diets said to work by lowering reward intensity and thus "lowering" fat set point actually meet this criteria? Seth Roberts is supposedly maintaining his weight with 1200 kcal a day and this seems to be what most of his followers end up eating as well, which is more comparable to the average daily intake of severe anorexics than of the constitutionally lean.
My impression is that low-carb, low-fat, raw vegan and other low-reward diets have a strong appetite-suppressing effect, but that this is not necessarily the same as "lowering" the body fat set point, which I construe rather as a wider physiological transformation to more closely resemble the metabolism of a constitutionally lean person. Lots of people who try these diets end up "spontaneously" eating so little that they rapidly develop symptoms of starvation and hypothyroidism, which I don't think should happen if the diets were actually effecting a drop in the body fat set point.
Hi Mike,
India has a huge obesity and diabetes problem in urban areas, and has one of the highest rates of cardiovascular mortality. Their food can be heavily flavored, but traditionally most people predominantly ate simple, low-fat foods. If you look at Southern India for example, the diet was mostly plain rice, legumes and a little coconut. I don't think you can make too many conclusions about average Indian food based on American-Indian or European-Indian restaurants, or even the cooking of affluent Indian households.
I suspect if you look at what the average Chinese person was eating 20 years ago, it would have been very plain. Today, particularly in affluent areas of cities, the food is more flavorful and diverse, and obesity and associated conditions are increasing dramatically.
Hi Collden,
You raise a very important point. Seth Roberts claims to eat an amount of food that strikes me as unhealthy. No offense to Dr. Roberts, but I'd like to see an objective quantification of exactly how much he eats in a day. It can be tough accurately estimating calorie intake. But the other possibility is that his technique doesn't really lower the setpoint.
I wish the bland food diet studies had continued for a longer time. What I'd like to see is that spontaneous food intake rebounds to a normal level once they've leaned out. That is exactly what you see in rodents-- hypophagia only continues until fat mass has been brought in line with the setpoint.
It's possible that there are permanent alterations to homeostatic and/or food reward pathways in the obese that make achieving true leanness difficult or even unhealthy. That's something that is currently being investigated. I think one way of getting at that would be too look at people who have had Roux-en-y gastric bypass surgery. For a number of reasons, I think that surgery probably works primarily because it disrupts gastric signaling that encodes food reward information. It would be interesting to see what their calorie intake, thyroid status, etc. is.
I'm not sure about your statement that lean people have higher BMR per unit lean mass. In rodents, the reverse is true, and that effect is dependent on leptin. Do you have a reference for that?
What about maintenance after losing the weight with a blander diet? If the palatability is increased, will the setpoint rise again?
It seems that you answered the maintenance question while I was writing.
Thanks, Stephan.
AFAIK, Southern Indians ate the sorts of things you mention, but was the food *bland* which was what was at issue? And, anyway, the food was so unhealthy (as you'll know from McCarrison's writings, if nowhere else, better than I) that whether it made you fat or not it would kill you pretty darn quick.
Were Northern Indians throughout, say, the 19th century, with a more healthy--and I'd think probably higher fat--diet obese? Not as far as I know. But, again, I don't believe the diet was bland.
As for the Chinese, all you're offering is your suspicions. Now, I think in rural China among the poor in the last century food could be very ordinary. IIRC, Joseph W. Esherick (The Origins of the Boxer Uprising) cites rural Chinese who had nothing much more to eat at times than boiled turnips. But that can't apply to all Chinese at all times and in places, but were all those to whom that didn't apply fat? Maybe they were and maybe not (although I kind of doubt it) but where's the evidence?
And you didn't address the fact that the Chinese do, at least currently, often cook hot. Do we know for sure they didn't in the past?
The rats overeating the chocolate-flavored food, and the 1965 hospital machine are telling stories, but I'm not totally convinced on the bland food. Vietnam, again, has very spicy food. There, I guess, there's just not enough food to go round, so it probably doesn't signify what appetites are switched on or off. But I'm still not convinced about India or China (or France).
Stephan eats potatoes morning, noon and night! Oh my!! ;)
Stephan: Would you please consider getting a glucose meter and some strips and monitoring your BG every 30 minutes one day from the time you get up until you go to sleep? I think this may well be instructive for your readers to see. Please? Oh pretty please do consider it!
I also think it might be helpful to others if you were to accurately (as in weigh/measure) log foods into Fitday or some similar type program for perhaps a week. Obviously this wouldn't do a thing for you, but it might help others to have the information rather than speculating/guesstimating on your own estimations.
Stephan
In rodents, there is no rebound weight gain when they start to eat normally again? Have things like energy expenditure per unit mass and thyroid function been studied in these rodent bland diet experiments?
Some refs,
Energy expenditure adjusted for body composition differentiates constitutional thinness from both normal subjects and anorexia nervosa
Balance in ghrelin and leptin plasma levels in anorexia nervosa patients and constitutionally thin women
BMR variability in women of different weight
And one more,
Basal metabolism and postprandial thermogenesis in anorexia nervosa and constitutional leanness
@CarbSane
Why do you think Stephan posting his blood glucose levels would be instructive? I don't think it would provide information that would translate to most of his readers. Metabolically healthy insulin sensitive people generally maintain relatively low blood glucose levels even after a high carbohydrate meal. A person with insulin resistance (including temporary low carb induced insulin resistance) will see higher post meal glucose levels.
So diabetics, pre-diabetics, and low carb dieters (IE much of his readers) could all be expected to have a much higher glucose level than Stephan after the same meal.
Hi Lisa,
If food reward goes back up, so will the setpoint.
Hi Collden,
Thanks for the references. I think the issue is that I didn't understand what you meant by "constitutional thinness/leanness". These people aren't just lean, they're extremely skinny (BMI ~17). I'm not sure what's going on with them, or if it can be applied to the general population. The studies you sent me support the idea that metabolic rate per unit lean mass is higher in obese people than normal lean people, which is what I thought you were referring to before.
The rodent studies I was referring to started with rodents made obese by force feeding or highly palatable refined diets. When you either stop overfeeding them or put them back on unrefined rodent chow, they become hypophagic until they lose most or all of the fat, after which they eat normally and do not rebound. However, they will rebound if you give them highly palatable food again.
Hi Mike,
N Indians were traditionally eating a highER fat diet compared with S Indians, but still low-fat by modern standards. The staple food was simple whole wheat chappatis. They were also heavier than their S Indian counterparts.
Look at the China Study if you want a reference for the blandness of the average "traditional" Chinese diet. In the 1980s, in almost every region studied, they were getting 70+ percent of their calories from plain rice, other grains or in some cases wheat. Traditional is in quotes because the Chinese diet has changed dramatically over the course of the last 150 years.
Hi CarbSane,
Yes, I do like potatoes, haha. I like sweet potatoes too, but they're too sweet for me to eat as a staple. I do sometimes check my blood glucose an hour after dinner. It usually peaks around 110-120 mg/dL after eating 120+ grams of carb at a sitting, typically mostly from potatoes. Morning fasting glucose is typically 85-90.
@Stephan: I just finally got to listen to the rest of your interview. I'm wondering if you could provide a citation about the estrogen leptin-sensitivity connection. I'd appreciate that greatly as I'm one of those postmeno women who would like to shed the rest of my excess weight! Alternately (especially if full text is not available), if you could email me through my profile on blogger that would be great. Thanks!
Hi CarbSane,
Here are some references related to the effect of estrogen in the brain and on leptin signaling:
Estrogen deficiency causes central leptin insensitivity and increased hypothalamic NPY
http://www.ncbi.nlm.nih.gov/pubmed/11753591
Gonadal hormones determine sensitivity to central leptin and insulin
http://www.ncbi.nlm.nih.gov/pubmed/16567519
Silencing of estrogen receptor alpha in the VMN of the hypothalamus leads to metabolic syndrome
http://www.ncbi.nlm.nih.gov/pubmed/17284595
My cookbook states that beans turn mushy if you soak them for so long (24 hours). Can anyone comment on that?
One (perhaps frivolous) question I was left with after listening to the podcast was: do you think chewing gum has an effect on the food reward pathway?
I could imagine that it might partially in terms of flavor, but I was curious more about the physical act of chewing and the memories associated with that action.
Hello Stephan, I have decided to take the challenge you presented on in the podcast (although it's against your recommendation) to try the monotonous diet. The reason being, I have already reached a low BMI of 18.5 (5'9", from 150 to 125 lbs. through calorie restriction), and I'm determined to maintain this body fat reduction.
I am currently using a diet of whey isolate (0g fat, 1g carb, 25 g protein per serving) and white rice only. I am coming off a diet restricted in carbohydrates, and I suspect that the simple matter of changing my diet itself will be enough to disrupt the food reward system in my body. Furthermore, I am in the unique situation of being able to eat continuously at my desk at during the day, and so I can try to eat so as to minimize the chance of caloric surplus at any given time. Also, since there is essentially no fat in my diet, I'd guess there would very little chance of triglyceride esterfication and storage. I wouldn't think this could be any worse than an all-potato diet.
Thanks
Hi Stephan
How does the speed of eating impact on food reward.
As kids you're always told "eat slowly", is this just an old wives tale?
Andrew
Thanks Stephan. Maybe some sort of hormone therapy may be in order here.
Hi Stephan,
I was just curious why you've eating a 50/50 mix of brown/white rice?
Thanks,
Mark
Stephan,
Your diet sounds quite bland. When you switched to this diet, from what I presume was a far more palatable diet, did you suffer cravings, lack of energy, anhedonia or anything like that?
I was wondering what you think about this strategy. Say a person were to follow an exceedingly bland diet until their weight stabilizes. At that point, what if they were to eat a relatively palatable diet one day and the very bland diet the next? One day on, one day off, continually. And place a calorie restriction on their palatable day, maintenance level or slightly below even. Ad libitum on the bland day. Could that potentially work to maintain the weight loss without sacrificing more enjoyable food?
Also, you mentioned in the podcast that a diet based on “gentle cooking”, as opposed to high heat cooking, leads to decreases in inflammation. Could this be due to the lower palatability of lightly cooked foods leading to a decreased calorie intake, and a reduction in the energy imbalance that you believe to be a major cause of trouble?
In terms of a southern Indian diet:
Yes, it can be "plain" and certainly less spiced than at an Indian restaurant. But lets also be honest that it very easy to overeat on it. Plenty of fat people eating a very traditional diet in South India. Idili eating competitions are usual as kids. Also kids love idili dipped into sugar.
Overal, however, that diet kept people slim because they didn't get enough to eat and were starving. Poverty overrides everything else.
In modern life, you see plenty of hyperslim southern indians getting heart attacks at 40, even with a pure vegetarian diet. Massive use of vegatable oil for cooking is probably a cause. Coconut oil is also not as good for you as we like to think.
The sikh study did conclude that that punjabi butter and wheat diet made for hardier soldiers.
"If food reward goes back up, so will the setpoint."
So, if you were to eat a diet extremely low in palatability (like an all-potato diet or a bland liquid diet) to lean out, would returning to a mostly non-processed whole food diet once you reach your desired leanness cause the fat to return? If increasing food reward even a modest amount at the end of a fat loss period leads to fat gain, aren't you doomed to eat that way forever? I'm not sure that's any more realistic than expecting people to maintain calorie restriction, fat restriction, or carb restriction in the long-term. How is restricting food reward a better strategy than other types of restrictive diets?
Hi Stephan,
Regarding the "bland food" hypothesis, can you address this nonscientific observation?
A lot of people I know, including some relatives by marriage and my kids, *love* bland food. By this I mean starches, and if grain, refined starches. White rice, white pasta, white bread, pretzels, potatoes, oatmeal, and even plain matzoh. These certain relatives, including my spouse (but not so much my kids so far), have a tendency to put on weight.
Usually a little salt helps the starch go down, and sometimes butter, but they seem to love the unadulterated starch on its own merits.
My dear, overweight, always-dieting mother-in-law who has hypertension and atherosclerosis, once brought over some plain matzohs and "lite" margarine for herself as a treat. I felt like shouting, "If you're going to do that, at least use real butter!" But I kept my mouth shut.
The food she cooks tends to be low-fat and low-salt and not highly seasoned, and yet the whole family has trouble keeping off the pounds. The family cuisine has been this way for the past twenty years at least, according to my husband.
Can you comment on people craving bland starches? It seems to me that they're calorically rewarding, so one might start to crave them due to the body's making an association, but how does this fit in with your theory, and with the recommendation for a bland diet?
Helen,
I can't comment about putting on weight because I'm young and have never had much body fat, but I do notice a few interesting things when eating more starch: first, I seem to need to eat until physical discomfort and never achieve a simple satiated feeling; I crave more protein; soon after, I have strong cravings for starch (either later that day or the following day if I eat it at night); I lose [lean] weight unless I consciously overeat. With high fat, I have little appetite for protein and spend less time thinking about food. I don't really know what that all means, but the protein thing is interesting. Emily Deans once wrote about sucrose binges leading to anxiety while fat binges don't--I wonder if it happens with glucose/starch.
Hi Charlie,
South Indian coronary problems was the subject of U.K. "Lancet" journal data for full term Mysore hospital births (1934 - 1954). Half were upper class and others lower social order babies studied in 1993 (ie: 40 to 60 years old birth data). For general information: the vegetable oil used in their era was mustard seed oil.
Synopsis is that there is an association (parsed for confounders) for babies born with both head size and birth weight at lowest ranges to have more coronary problems. The South India relationship of coronary heart disease with low birth weight matched study in the British Medical Journal (1993) regarding UK coronary frequency and low birth weight.
Excellent podcast. Stephan has caused quite a stir in the Paleo, HFLC community. I view that as a good thing. It is healthy to constantly question one's assumptions.
The set point theory raises more questions than it answers. I am particularly curious about individual micronutrients and whether they produce the reward stimulus individually or in combinations? Fat, for example, probably doesn't. But combining it with sugar and flour (a donut) will.
And salt is intriguing. Is it salt alone that stimulates the reponse, or in combination with other nutrients or textures? This theory also explains why Paleo may be superior to other diets because of the nutritional value and lack of Neolithic, insalubrious additives.
I should also add that fat, by itself, does not appear to be stimulative. If that were the case, the Plains Indians and Inuit would not have been the lean specimens they were documented to be. Lewis and Clark, among many others, described them as splendid humans in both form and stature. Yet the Plains Indians lived part of the year on Pemmican (60-80 percent fat). And the Inuit ate blubber.
Yet both groups suffered from epidemic rates of diabetes and obesity when introduced to sugar and flour. Fat, like salt, may be healthy unless combined with Neolithic ingredients.
Just spit balling here.
These are very interesting directions to pursue. I've been thinking about the set point and bland food ideas from perspectives of learning (something I study for a living) and traditional foods.
I think there's another approach that may be complementary (or not) to the bland foods idea. Preparations of traditional foods tend to vary in taste, texture, saltiness, etc., whereas modern industrially processed foods do not. This is not always the case, of course, but collecting and processing your own food literally "from scratch" tends to introduce numerous variances, some subtle, others not. In contrast, fast food always tastes the same.
Basically, varying food reward may be an alternative or complement to eating bland foods.
As an aside, traditional foods my grandparents ate (in former Yugoslavia) included very spicy and very salty foods eaten together with bland foods. For example, salted fish with freshly baked bread and strong red wine. Or lard with paprika and polenta. Obesity was nonexistent, even among the "wealthy" who could afford to eat virtually unlimited amounts. I'm sure there are similar cases in other traditional diets and it's something every food reward perspective should, I think, take seriously.
I agree based on the number of cultures that consume higher carb and are healthy that it does seem like the way to go if you can handle it.
If someone has a messed up gut environment, then things like carbs tend to be a digestive difficulty. Do you think healing the gut should take priority over venturing into implementing a higher carb diet. And do you know of any good ways to heal the gut (such as the GAPS diet, etc).
So you would essentially go on a higher fat diet to help set things dtraight, then once your gut is in order you could implement more carbs?
What do you think?
Have you forsaken the unsweetened chocolate? (I forget, was that a treat or was it medicine?)
Any estimate (or actual measurement) of typical daily caloric intake?
Hi BluetoothEnable,
Would you explain what you are attempting to do? It would be interesting to hear what age you started self-experimenting like this.
I have been doing Stephan's original recipe of a liquid diet but find that blended sardines are way too over powering. Beeturia isn't nice either, lol. The taste isn't actually that bad, but people can smell me coming from a block away.
My greatest fear came from raw eggs and liver/kidney. To my surprise raw or less cooked meats actually have an almost completely benign character (flavor, smell, texture).
Stephan, in the podcast you mentioned research papers that address diabetes and cooking methods. Could you cite some of these papers so I can have a look?
Thanks, Michael
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I genuinely feel sorry for Stephan with his boring bland (and to me, unsatisfying) spuds three times a day and with the potentially best part of the diet, the beef, in its least-appetising, least-appealing form, ground (minced).
My (English) ancestors apparently refused to eat spuds for a long time, not believing that they were food fit for humans. (My compatriots have made up for this now though as potato chips (fries to you) accompany virtually every meal (not mine of course). The only way to make a potato palatable is to slather it in animal fat.
I believe in cutting out the middle man and having my animal fat on animals. You may find my diet(*) boring as well, but it's certainly not bland or unsatisfying, and I doubt if I eat more calories than you.
(*Meat (fresh, unprocessed), eggs, optional cheese, optional organ meat, optional fish, cooked (gently) in beef dripping and|or butter and|or coconut oil). Preparation time about 1 minute. Cooking time about 5 minutes. Shopping methodology: very simple. Never get bored with it. Don't feel hungry between meals; don't eat snacks).
I think there are some interesting posts up here.
I would agree that based on certain cultures that seem to be healthy and lean despite eating a higher carb diet is a valid point in that carbs are not necessarily 'bad'. BUT what I find interesting is that carbs are absolutely NOT necessary. You won't die if you don't have them. You can live entirely on meat (as the Inuit did) and live a healthy long life, yet you can't live on vegetable, starch and grains etc. That to me alone convinces me that it's perfectly fine to reduce the amount of carbs in my diet. My digestion have improved significantly, my skin has cleared up, and my hair seems to be healthier too.
I would say the only reason why I bother with any carbs at all is a) I do enjoy vegetables. b) I am in an environment where other people around me eat them constantly and I feel obligated to indulge in them once in a while...
I also like to note the importance of fat. I think before when I was eating a standard diet I wasn't getting enough fat. This was not a result of any type of dieting at all. I ate whatever I wanted simply because I felt that since I was slim and in shape, I could. But even still, my fat intake was naturally lower because of the foods just naturally have less fat. Since increasing my fat intake I don't feel such variations in body temperature (hooray, I can now tolerate 15°C w/o feeling FREEZING), and I feel that my endurance has improved.
The greatest thing I enjoy as a result of eating HF: LC (and moderate protein) is that my digestion is perfect now. That to me alone is worth everything. :-)
*I want the email follow up comments, so am commenting again to use this option*
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