A reader sent me a link to a recent CBS documentary titled "Tweaking Tastes and Creating Cravings", reported by Morley Safer.
Safer describes the "flavorist" industry, entirely dedicated to crafting irresistible odors for the purpose of selling processed and restaurant food. They focused on the company Givaudin. Dr. David Kessler, author of The End of Overeating, makes an appearance near the end.
Here are a few notable quotes:
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Showing posts with label Food reward. Show all posts
Showing posts with label Food reward. Show all posts
New Review Papers on Food Reward
As research on the role of reward/palatability in obesity continues to accelerate, interesting new papers are appearing weekly. Here is a roundup of review papers I've encountered in the last three months. These range from somewhat technical to very technical, but I think they should be mostly accessible to people with a background in the biological sciences.
Food and Drug Reward: Overlapping Circuits in Human Obesity and Addiction
Written by Dr. Nora D. Volkow and colleagues. This paper describes the similarities between the mechanisms of obesity and addiction, with a focus on human brain imaging studies. Most researchers don't think obesity is an addiction per se, but the mechanisms (e.g., brain areas important for reward) do seem to overlap considerably. This paper is well composed and got a lot of media attention. Dr. Volkow is the director of the National Institute on Drug Abuse, a branch of the National Institutes of Health. The NIH is the main source of biomedical research funding in the US, and also conducts its own research.
Here's a quote from the paper:
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Food and Drug Reward: Overlapping Circuits in Human Obesity and Addiction
Written by Dr. Nora D. Volkow and colleagues. This paper describes the similarities between the mechanisms of obesity and addiction, with a focus on human brain imaging studies. Most researchers don't think obesity is an addiction per se, but the mechanisms (e.g., brain areas important for reward) do seem to overlap considerably. This paper is well composed and got a lot of media attention. Dr. Volkow is the director of the National Institute on Drug Abuse, a branch of the National Institutes of Health. The NIH is the main source of biomedical research funding in the US, and also conducts its own research.
Here's a quote from the paper:
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Another Simple Food Weight Loss Experience
Whole Health Source reader Sarah Pugh recently went on a six-week simple food (low reward) diet to test its effectiveness as a weight loss strategy, and she was kind enough to describe her experience for me, and provide a link to her blog where she discussed it in more detail (1).
Consistent with the scientific literature and a number of previous reader anecdotes (2), Sarah experienced a reduction in appetite on the simple food diet, losing 15 pounds in 6 weeks without hunger. In contrast to her prior experiences with typical calorie restriction, her energy level and mood remained high over this period. Here's a quote from her blog:
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Consistent with the scientific literature and a number of previous reader anecdotes (2), Sarah experienced a reduction in appetite on the simple food diet, losing 15 pounds in 6 weeks without hunger. In contrast to her prior experiences with typical calorie restriction, her energy level and mood remained high over this period. Here's a quote from her blog:
Well, it looks like the theory that in the absence of nice palatable food, the body will turn quite readily to fat stores and start munching them up, is holding up. At the moment, the majority of the energy I use is coming from my insides, and my body is using it without such quibbles as the increased hunger, low energy, crappy thermo-regulation or bitchiness normally associated with severe calorie restriction.I can't promise that everyone will experience results like this, but this is basically what the food reward hypothesis suggests should be possible, and it seems to work this way for many people. That's one of the reasons why this idea interests me so much.
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A Brief Response to Taubes's Food Reward Critique, and a Little Something Extra
It appears Gary Taubes has completed his series critiquing the food reward hypothesis of obesity (1). I have to hand it to him, it takes some cojones to critique an entire field of research, particularly when you have no scientific background in it.
The food reward hypothesis of obesity states that the reward and palatability value of food influence body fatness, and excess reward/palatability can promote body fat accumulation. If we want to test the hypothesis, the most direct way is to find experiments in which 1) the nutritional qualities of the experimental diet groups are kept the same or at least very similar, 2) some aspect of diet reward/palatability differs, and 3) changes in body fat/weight are measured (for example, 2, 3, 4, 5, 6, 7, 8, 9). Taubes repeatedly stated in his series that controlled studies like these have not been conducted, apparently basing this belief on a 22-year-old review paper by Dr. Israel Ramirez and colleagues that does not contain the word 'reward' (10). Another way to test the hypothesis is to see if people with higher food reward sensitivity (due to genetics or other factors) tend to gain more fat over time (for example, 11, 12, 13, 14, 15, 16). In addition, studies that have examined the effect of palatability/reward on food intake in a controlled manner are relevant (17, 18, 19, 20, 21, 22), as are studies that have identified some of the mechanisms by which these effects occur (reviewed in 23). Even if not all of the studies are perfect, at some point, one has to acknowledge that there are a lot of mutually buttressing lines of evidence here. It is notable that very few of these studies appeared in Taubes's posts.
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The food reward hypothesis of obesity states that the reward and palatability value of food influence body fatness, and excess reward/palatability can promote body fat accumulation. If we want to test the hypothesis, the most direct way is to find experiments in which 1) the nutritional qualities of the experimental diet groups are kept the same or at least very similar, 2) some aspect of diet reward/palatability differs, and 3) changes in body fat/weight are measured (for example, 2, 3, 4, 5, 6, 7, 8, 9). Taubes repeatedly stated in his series that controlled studies like these have not been conducted, apparently basing this belief on a 22-year-old review paper by Dr. Israel Ramirez and colleagues that does not contain the word 'reward' (10). Another way to test the hypothesis is to see if people with higher food reward sensitivity (due to genetics or other factors) tend to gain more fat over time (for example, 11, 12, 13, 14, 15, 16). In addition, studies that have examined the effect of palatability/reward on food intake in a controlled manner are relevant (17, 18, 19, 20, 21, 22), as are studies that have identified some of the mechanisms by which these effects occur (reviewed in 23). Even if not all of the studies are perfect, at some point, one has to acknowledge that there are a lot of mutually buttressing lines of evidence here. It is notable that very few of these studies appeared in Taubes's posts.
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Losing Fat With Simple Food-- Two Reader Anecdotes
Each week, I'm receiving more e-mails and comments from people who are successfully losing fat by eating simple (low reward) food, similar to what I described here. In some cases, people are breaking through fat loss plateaus that they had reached on conventional low-carbohydrate, low-fat or paleo diets. This concept can be applied to any type of diet, and I believe it is an important characteristic of ancestral food patterns.
At the Ancestral Health Symposium, I met two Whole Health Source readers, Aravind Balasubramanian and Kamal Patel, who were interested in trying a simple diet to lose fat and improve their health. In addition, they wanted to break free of certain other high-reward activities in their lives that they felt were not constructive. They recently embarked on an 8-week low-reward diet and lifestyle to test the effectiveness of the concepts. Both of them had previously achieved a stable (in Aravind's case, reduced) weight on a paleo-ish diet prior to this experiment, but they still carried more fat than they wanted to. They offered to write about their experience for WHS, and I thought other readers might find it informative. Their story is below, followed by a few of my comments.
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At the Ancestral Health Symposium, I met two Whole Health Source readers, Aravind Balasubramanian and Kamal Patel, who were interested in trying a simple diet to lose fat and improve their health. In addition, they wanted to break free of certain other high-reward activities in their lives that they felt were not constructive. They recently embarked on an 8-week low-reward diet and lifestyle to test the effectiveness of the concepts. Both of them had previously achieved a stable (in Aravind's case, reduced) weight on a paleo-ish diet prior to this experiment, but they still carried more fat than they wanted to. They offered to write about their experience for WHS, and I thought other readers might find it informative. Their story is below, followed by a few of my comments.
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The Case for the Food Reward Hypothesis of Obesity, Part II
In this post, I'll explore whether or not the scientific evidence is consistent with the predictions of the food reward hypothesis, as outlined in the last post.
Before diving in, I'd like to address the critique that the food reward concept is a tautology or relies on circular reasoning (or is not testable/falsifiable). This critique has no logical basis. The reward and palatability value of a food is not defined by its effect on energy intake or body fatness. In the research setting, food reward is measured by the ability of food or food-related stimuli to reinforce or motivate behavior (e.g., 1). In humans, palatability is measured by having a person taste a food and rate its pleasantness in a standardized, quantifiable manner, or sometimes by looking at brain activity by fMRI or related techniques (2). In rodents, it is measured by observing stereotyped facial responses to palatable and unpalatable foods, which are similar to those seen in human infants. It is not a tautology or circular reasoning to say that the reinforcing value or pleasantness of food influences food intake and body fatness. These are quantifiable concepts and as I will explain, their relationship with food intake and body fatness can be, and already has been, tested in a controlled manner.
1. Increasing the reward/palatability value of the diet should cause fat gain in animals and humans
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Before diving in, I'd like to address the critique that the food reward concept is a tautology or relies on circular reasoning (or is not testable/falsifiable). This critique has no logical basis. The reward and palatability value of a food is not defined by its effect on energy intake or body fatness. In the research setting, food reward is measured by the ability of food or food-related stimuli to reinforce or motivate behavior (e.g., 1). In humans, palatability is measured by having a person taste a food and rate its pleasantness in a standardized, quantifiable manner, or sometimes by looking at brain activity by fMRI or related techniques (2). In rodents, it is measured by observing stereotyped facial responses to palatable and unpalatable foods, which are similar to those seen in human infants. It is not a tautology or circular reasoning to say that the reinforcing value or pleasantness of food influences food intake and body fatness. These are quantifiable concepts and as I will explain, their relationship with food intake and body fatness can be, and already has been, tested in a controlled manner.
1. Increasing the reward/palatability value of the diet should cause fat gain in animals and humans
Read more »
The Case for the Food Reward Hypothesis of Obesity, Part I
Introduction
When you want to investigate something using the scientific method, first you create a model that you hope describes a natural phenomenon-- this is called a hypothesis. Then you go about testing that model against reality, under controlled conditions, to see if it has any predictive power. There is rarely a single experiment, or single study, that can demonstrate that a hypothesis is correct. Most important hypotheses require many mutually buttressing lines of evidence from multiple research groups before they're widely accepted. Although it's not necessary, understanding the mechanism by which an effect occurs, and having that mechanism be consistent with the hypothesis, adds substantially to the case.
With that in mind, this post will go into greater detail on the evidence supporting food reward and palatability as major factors in the regulation of food intake and body fatness. There is a large amount of supportive evidence at this point, which is rapidly expanding due to the efforts of many brilliant researchers, however for the sake of clarity and brevity, so far I've only given a "tip of the iceberg" view of it. But there are two types of people who want more detail: (1) the skeptics, and (2) scientifically inclined people who want mechanism. This post is for them. It will get technical at times, as there is no other way to convey the material effectively.
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When you want to investigate something using the scientific method, first you create a model that you hope describes a natural phenomenon-- this is called a hypothesis. Then you go about testing that model against reality, under controlled conditions, to see if it has any predictive power. There is rarely a single experiment, or single study, that can demonstrate that a hypothesis is correct. Most important hypotheses require many mutually buttressing lines of evidence from multiple research groups before they're widely accepted. Although it's not necessary, understanding the mechanism by which an effect occurs, and having that mechanism be consistent with the hypothesis, adds substantially to the case.
With that in mind, this post will go into greater detail on the evidence supporting food reward and palatability as major factors in the regulation of food intake and body fatness. There is a large amount of supportive evidence at this point, which is rapidly expanding due to the efforts of many brilliant researchers, however for the sake of clarity and brevity, so far I've only given a "tip of the iceberg" view of it. But there are two types of people who want more detail: (1) the skeptics, and (2) scientifically inclined people who want mechanism. This post is for them. It will get technical at times, as there is no other way to convey the material effectively.
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Humans on a Cafeteria Diet
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Book Review: The End of Overeating
The End of Overdating was written based on the personal journey of Dr. David A. Kessler (MD) to understand the obesity epidemic, and treat his own obesity in the process. Kessler was the FDA commissioner under presidents George HW Bush and Bill Clinton. He is known for his efforts to regulate cigarettes, and his involvement in modernizing Nutrition Facts labels on packaged food. He was also the dean of Yale medical school for six years-- a very accomplished person.
Kessler's book focuses on 1) the ability of food with a high palatability/reward value to cause overeating and obesity, 2) the systematic efforts of the food industry to maximize food palatability/reward to increase sales in a competitive market, and 3) what to do about it. He has not only done a lot of reading on the subject, but has also participated directly in food reward research himself, so he has real credibility. The End of Overeating is not the usual diet book baloney.
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Kessler's book focuses on 1) the ability of food with a high palatability/reward value to cause overeating and obesity, 2) the systematic efforts of the food industry to maximize food palatability/reward to increase sales in a competitive market, and 3) what to do about it. He has not only done a lot of reading on the subject, but has also participated directly in food reward research himself, so he has real credibility. The End of Overeating is not the usual diet book baloney.
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A Roadmap to Obesity
In this post, I'll explain my current understanding of the factors that promote obesity in humans.
Heritability
To a large degree, obesity is a heritable condition. Various studies indicate that roughly two-thirds of the differences in body fatness between individuals is explained by heredity*, although estimates vary greatly (1). However, we also know that obesity is not genetically determined, because in the US, the obesity rate has more than doubled in the last 30 years, consistent with what has happened to many other cultures (2). How do we reconcile these two facts? By understanding that genetic variability determines the degree of susceptibility to obesity-promoting factors. In other words, in a natural environment with a natural diet, nearly everyone would be relatively lean, but when obesity-promoting factors are introduced, genetic makeup determines how resistant each person will be to fat gain. As with the diseases of civilization, obesity is caused by a mismatch between our genetic heritage and our current environment. This idea received experimental support from an interesting recent study (3).
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Heritability
To a large degree, obesity is a heritable condition. Various studies indicate that roughly two-thirds of the differences in body fatness between individuals is explained by heredity*, although estimates vary greatly (1). However, we also know that obesity is not genetically determined, because in the US, the obesity rate has more than doubled in the last 30 years, consistent with what has happened to many other cultures (2). How do we reconcile these two facts? By understanding that genetic variability determines the degree of susceptibility to obesity-promoting factors. In other words, in a natural environment with a natural diet, nearly everyone would be relatively lean, but when obesity-promoting factors are introduced, genetic makeup determines how resistant each person will be to fat gain. As with the diseases of civilization, obesity is caused by a mismatch between our genetic heritage and our current environment. This idea received experimental support from an interesting recent study (3).
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Food Palatability and Body Fatness: Clues from Alliesthesia
Part I: Is there a Ponderostat?
Some of the most important experiments for understanding the role of food palatability/reward in body fatness were performed by Dr. Michel Cabanac and collaborators in the 1970s (hat tip to Dr. Seth Roberts for the references). In my recent food reward series (1), I referenced but did not discuss Dr. Cabanac's work because I felt it would have taken too long to describe. However, I included two of his studies in my Ancestral Health Symposium talk, and I think they're worth discussing in more detail here.
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Some of the most important experiments for understanding the role of food palatability/reward in body fatness were performed by Dr. Michel Cabanac and collaborators in the 1970s (hat tip to Dr. Seth Roberts for the references). In my recent food reward series (1), I referenced but did not discuss Dr. Cabanac's work because I felt it would have taken too long to describe. However, I included two of his studies in my Ancestral Health Symposium talk, and I think they're worth discussing in more detail here.
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Interview on Super Human Radio
Today, I did an audio interview with Carl Lanore of Super Human Radio. Carl seems like a sharp guy who focuses on physical fitness, nutrition, health and aging. We talked mostly about food reward and body fatness-- I think it went well. Carl went from obese to fit, and his fat loss experience lines up well with the food reward concept. As he was losing fat rapidly, he told friends that he had "divorced from flavor", eating plain chicken, sweet potatoes and oatmeal, yet he grew to enjoy simple food over time.
The interview is here. It also includes an interview of Dr. Matthew Andry about Dr. Loren Cordain's position on dairy; my interview starts at about 57 minutes. Just to warn you, the website and podcast are both full of ads.
The interview is here. It also includes an interview of Dr. Matthew Andry about Dr. Loren Cordain's position on dairy; my interview starts at about 57 minutes. Just to warn you, the website and podcast are both full of ads.
Weight Gain and Weight Loss in a Traditional African Society
The Massas is an ethnic group in Northern Cameroon that subsists mostly on plain sorghum loaves and porridge, along with a small amount of milk, fish and vegetables (1, 2). They have a peculiar tradition called Guru Walla that is only undertaken by men (2, 1):
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Simple Food: Thoughts on Practicality
Some people have reacted negatively to the idea of a reduced-reward diet because it strikes them as difficult or unsustainable. In this post, I'll discuss my thoughts on the practicality and sustainability of this way of eating. I've also thrown in a few philosophical points about reward and the modern world.
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How Does Gastric Bypass Surgery Cause Fat Loss?
Gastric bypass surgery is an operation that causes food to bypass part of the digestive tract. In the most common surgery, Roux-en-Y bypass, stomach size is reduced and a portion of the upper small intestine is bypassed. This means that food skips most of the stomach and the duodenum (upper small intestine), passing from the tiny stomach directly into the jejunum (a lower part of the upper small intestine)*. It looks something like this:
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Food Reward: a Dominant Factor in Obesity, Part VIII
Further reading
I didn't come up with the idea that excessive food reward increases calorie intake and can lead to obesity, far from it. The idea has been floating around the scientific literature for decades. In 1976, after conducting an interesting diet study in humans, Dr. Michel Cabanac stated that the "palatability of the diet influences the set point of the ponderostat [system that regulates body fatness]" (1).
Currently there is a growing consensus that food reward/palatability is a major contributor to obesity. This is reflected by the proliferation of review articles appearing in high-profile journals. For the scientists in the audience who want more detail than I provide on my blog, here are some of the reviews I've read and enjoyed. These were written by some of the leading scientists in the study of food reward and hedonics:
Palatability of food and the ponderostat. Michel Cabanac, 1989.
Food reward, hyperphagia and obesity. Hans-Rudolf Berthoud et al., 2011.
Reward mechanisms in obesity: new insights and future directions. Paul J. Kenny, 2011.
Relation of obesity to consummatory and anticipatory food reward. Eric Stice, 2009.
Hedonic and incentive signals for body weight control. Emil Egecioglu et al., 2011.
Homeostatic and hedonic signals interact in the control of food intake. Michael Lutter and Eric J. Nestler, 2009.
Opioids as agents of reward-related feeding: a consideration of the evidence. Allen S. Levine and Charles J. Billington, 2004.
Central opioids and consumption of sweet tastants: when reward outweighs homeostasis. Pawel K. Olszewski and Allen S. Levine, 2007.
Oral and postoral determinants of food reward. Anthony Sclafani, 2004.
Reduced dopaminergic tone in hypothalamic neural circuits: expression of a "thrifty" genotype underlying the metabolic syndrome? Hanno Pijl, 2003.
If you can read all these papers and still not believe in the food reward hypothesis... you deserve some kind of award.
I didn't come up with the idea that excessive food reward increases calorie intake and can lead to obesity, far from it. The idea has been floating around the scientific literature for decades. In 1976, after conducting an interesting diet study in humans, Dr. Michel Cabanac stated that the "palatability of the diet influences the set point of the ponderostat [system that regulates body fatness]" (1).
Currently there is a growing consensus that food reward/palatability is a major contributor to obesity. This is reflected by the proliferation of review articles appearing in high-profile journals. For the scientists in the audience who want more detail than I provide on my blog, here are some of the reviews I've read and enjoyed. These were written by some of the leading scientists in the study of food reward and hedonics:
Palatability of food and the ponderostat. Michel Cabanac, 1989.
Food reward, hyperphagia and obesity. Hans-Rudolf Berthoud et al., 2011.
Reward mechanisms in obesity: new insights and future directions. Paul J. Kenny, 2011.
Relation of obesity to consummatory and anticipatory food reward. Eric Stice, 2009.
Hedonic and incentive signals for body weight control. Emil Egecioglu et al., 2011.
Homeostatic and hedonic signals interact in the control of food intake. Michael Lutter and Eric J. Nestler, 2009.
Opioids as agents of reward-related feeding: a consideration of the evidence. Allen S. Levine and Charles J. Billington, 2004.
Central opioids and consumption of sweet tastants: when reward outweighs homeostasis. Pawel K. Olszewski and Allen S. Levine, 2007.
Oral and postoral determinants of food reward. Anthony Sclafani, 2004.
Reduced dopaminergic tone in hypothalamic neural circuits: expression of a "thrifty" genotype underlying the metabolic syndrome? Hanno Pijl, 2003.
If you can read all these papers and still not believe in the food reward hypothesis... you deserve some kind of award.
Food Reward: a Dominant Factor in Obesity, Part VII
Now that I've explained the importance of food reward to obesity, and you're tired of reading about it, it's time to share my ideas on how to prevent and perhaps reverse fat gain. First, I want to point out that although food reward is important, it's not the only factor. Heritable factors (genetics and epigenetics), developmental factors (uterine environment, childhood diet), lifestyle factors (exercise, sleep, stress) and dietary factors besides reward also play a role. That's why I called this series "a dominant factor in obesity", rather than "the dominant factor in obesity".
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Drug Cessation and Weight Gain
Commenter "mem", who has been practicing healthcare for 30+ years, made an interesting remark that I think is relevant to this discussion:
It's clear that smoking cigarettes, taking cocaine and certain other pleasure drugs suppress appetite and can prevent weight gain. These drugs all activate dopamine-dependent reward centers, which is why they're addictive. Cocaine in particular directly inhibits dopamine clearance from the synapse (neuron-neuron junction), increasing its availability for signaling.
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Recovering substance dependent people often put on lots of weight and it is not uncommon for them to become obese or morbidly obese.This relates to the question that commenter "Gunther Gatherer" and I have been pondering in the comments: can stimulating reward pathways through non-food stimuli influence body fatness?
It's clear that smoking cigarettes, taking cocaine and certain other pleasure drugs suppress appetite and can prevent weight gain. These drugs all activate dopamine-dependent reward centers, which is why they're addictive. Cocaine in particular directly inhibits dopamine clearance from the synapse (neuron-neuron junction), increasing its availability for signaling.
Read more »
Food Reward: a Dominant Factor in Obesity, Part VI
Reward Centers can Modify the Body Fat Setpoint
Dopamine is a neurotransmitter (chemical that signals between neurons) that is a central mediator of reward and motivation in the brain. It has been known for decades that dopamine injections into the brain suppress food intake, and that this is due primarily to its action in the hypothalamus, which is the main region that regulates body fatness (1). Dopamine-producing neurons from reward centers contact neurons in the hypothalamus that regulate body fatness (2). I recently came across a paper by a researcher named Dr. Hanno Pijl, from Leiden University in the Netherlands (3). The paper is a nice overview of the evidence linking dopamine signaling with body fatness via its effects on the hypothalamus, and I recommend it to any scientists out there who want to read more about the concept.
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Dopamine is a neurotransmitter (chemical that signals between neurons) that is a central mediator of reward and motivation in the brain. It has been known for decades that dopamine injections into the brain suppress food intake, and that this is due primarily to its action in the hypothalamus, which is the main region that regulates body fatness (1). Dopamine-producing neurons from reward centers contact neurons in the hypothalamus that regulate body fatness (2). I recently came across a paper by a researcher named Dr. Hanno Pijl, from Leiden University in the Netherlands (3). The paper is a nice overview of the evidence linking dopamine signaling with body fatness via its effects on the hypothalamus, and I recommend it to any scientists out there who want to read more about the concept.
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Food Reward: a Dominant Factor in Obesity, Part V
Non-industrial diets from a food reward perspective
In 21st century affluent nations, we have unprecedented control over what food crosses our lips. We can buy nearly any fruit or vegetable in any season, and a massive processed food industry has sprung up to satisfy (or manufacture) our every craving. Most people can afford exotic spices and herbs from around the world-- consider that only a hundred years ago, black pepper was a luxury item. But our degree of control goes even deeper: over the last century, kitchen technology such as electric/gas stoves, refrigerators, microwaves and a variety of other now-indispensable devices have changed the way we prepare food at home (Megan J. Elias. Food in the United States, 1890-1945).
To help calibrate our thinking about the role of food reward (and food palatability) in human evolutionary history, I offer a few brief descriptions of contemporary hunter-gatherer and non-industrial agriculturalist diets. What did they eat, and how did they prepare it?
Read more »
In 21st century affluent nations, we have unprecedented control over what food crosses our lips. We can buy nearly any fruit or vegetable in any season, and a massive processed food industry has sprung up to satisfy (or manufacture) our every craving. Most people can afford exotic spices and herbs from around the world-- consider that only a hundred years ago, black pepper was a luxury item. But our degree of control goes even deeper: over the last century, kitchen technology such as electric/gas stoves, refrigerators, microwaves and a variety of other now-indispensable devices have changed the way we prepare food at home (Megan J. Elias. Food in the United States, 1890-1945).
To help calibrate our thinking about the role of food reward (and food palatability) in human evolutionary history, I offer a few brief descriptions of contemporary hunter-gatherer and non-industrial agriculturalist diets. What did they eat, and how did they prepare it?
Read more »
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