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Friday, 23 January 2015
Thursday, 15 January 2015
Does high protein explain the low-carb "metabolic advantage"?
In 2012, David Ludwig's group published a paper that caused quite a stir in the diet-nutrition world (1). They reported that under strict metabolic ward conditions, weight-reduced people have a higher calorie expenditure when eating a very low carbohydrate diet (10% CHO) than when eating a high-carbohydrate diet (60% CHO)*.
In other words, the group eating the low-carb diet burned more calories just sitting around, and the effect was substantial-- about 250 Calories per day. This is basically the equivalent of an hour of moderate-intensity exercise per day, as Dr. Ludwig noted in interviews (2). The observation is consistent with the claims of certain low-carbohydrate diet advocates that this dietary pattern confers a "metabolic advantage", allowing people to lose weight without cutting calorie intake-- although the study didn't actually show differences in body fatness.
In Dr. Ludwig's study, calorie intake was the same for all groups. However, the study had an important catch that many people missed: the low-carbohydrate group ate 50 percent more protein than the other two groups (30% of calories vs. 20% of calories). We know that protein can influence calorie expenditure, but can it account for such a large difference between groups?
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Wednesday, 7 January 2015
Is Meat Unhealthy? Part VI
In this post, I'll examine the possible relationship between meat consumption and cancer risk.
Is cancer risk even modifiable?
Cancer is caused by the uncontrolled division of a population of rogue cells in the body. These cells essentially evolve by natural selection to escape the body's multiple anti-cancer mechanisms.
To a large extent, cancer appears to be a numbers game. The human body contains about 37 trillion cells. To get cancer, all you need is one cell that develops key mutations that allow it to shed its built-in restrictions on cell division. The older you are, the more time you have to accumulate mutations, explaining why cancer risk rises sharply with age.
Unlike other common non-communicable diseases, we don't know to what extent cancer is caused by modifiable diet and lifestyle factors vs. bad luck that's completely outside our control. Some cancers, such as lung cancer, are typically linked to lifestyle factors like cigarette smoking-- yet the majority of cancers aren't so easily understood.
Friday, 2 January 2015
Friday, 26 December 2014
Tuesday, 16 December 2014
Is Meat Unhealthy? Part V
In this post, I'll examine the possible relationship between meat intake and type 2 diabetes. Type 2 diabetes is the most common form of diabetes, and it is strongly linked to lifestyle factors.
Non-industrial cultures
Non-industrial cultures have an extremely low prevalence of diabetes, whether they are near-vegan or near-carnivorous. This is supported by blood glucose measurements in a variety of cultures, from the sweet potato farmers of the New Guinea highlands to the arctic Inuit hunters. Here is what Otto Schaefer, director of the Northern Medical Research Unit at Charles Camsell hospital in Edmonton, Canada, had to say about the Inuit in the excellent book Western Diseases (Trowell and Burkitt, 1981):
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Friday, 12 December 2014
Friday, 5 December 2014
Wednesday, 3 December 2014
Is Meat Unhealthy? Part IV
In this post, I'll address the question: does eating meat contribute to weight gain?
Non-industrial cultures
I'll get right to the point: humans living in a non-industrialized setting tend to be lean, regardless of how much meat they eat. This applies equally to hunter-gatherers, herders, and farmers.
One of the leanest populations I've encountered in my reading is the 1960s Papua New Guinea highland farmers of Tukisenta. They ate a nearly vegan diet composed almost exclusively of sweet potatoes, occasionally punctuated by feasts including large amounts of pork. On average, they ate very little animal food. Visiting researchers noted that the residents of Tukisenta were "muscular and mostly very lean", and did not gain fat with age (1, Western Diseases, Trowell and Burkitt, 1981).
Another remarkably lean hunter-gatherer population is the !Kung San foragers of the Kalahari desert. The !Kung San are so lean that many of them would be considered underweight on the standard body mass index scale (BMI less than 18.5). Average BMI doesn't exceed 20 in any age category (The !Kung San, Richard Lee, 1979). Is this simply because they're starving? It is true that they don't always get as much food as they'd like, but on most days, they have the ability to gather more food than they need. The fact that they are able to reproduce normally suggests that they aren't starving. Richard Lee's detailed work with the !Kung San indicates that approximately 40 percent of their calories came from animal foods during his study period in the 1960s. This was mostly meat, with occasional eggs when available.
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Non-industrial cultures
I'll get right to the point: humans living in a non-industrialized setting tend to be lean, regardless of how much meat they eat. This applies equally to hunter-gatherers, herders, and farmers.
One of the leanest populations I've encountered in my reading is the 1960s Papua New Guinea highland farmers of Tukisenta. They ate a nearly vegan diet composed almost exclusively of sweet potatoes, occasionally punctuated by feasts including large amounts of pork. On average, they ate very little animal food. Visiting researchers noted that the residents of Tukisenta were "muscular and mostly very lean", and did not gain fat with age (1, Western Diseases, Trowell and Burkitt, 1981).
 |
| !Kung man gathering mongongo fruit/nuts. From The !Kung San, by Richard B. Lee. |
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Monday, 1 December 2014
Recent Interviews
For those who don't follow my Twitter account (@whsource), here are links to my two most recent interviews.
Smash the Fat with Sam Feltham. We discuss the eternally controversial question, "is a calorie a calorie"? Like many other advocates of the low-carbohydrate diet, Feltham believes that the metabolic effects of food (particularly on insulin), rather than calorie intake per se, are the primary determinants of body fatness. I explain the perspective that my field of research has provided on this question. We also discussed why some lean people become diabetic. Feltham was a gracious host.
Nourish, Balance, Thrive with Christopher Kelly. Kelly is also an advocate of the low-carbohydrate diet for fat loss. This interview covered a lot of ground, including the insulin-obesity hypothesis, regulation of body fatness by the leptin-brain axis, how food reward works to increase calorie intake, and the impact of the food environment on food intake. I explain why I think proponents of the insulin-obesity hypothesis have mistaken association for causation, and what I believe the true relationship is between insulin biology and obesity. Kelly was also a gracious host. He provides a transcript if you'd rather read the interview in text form.
Smash the Fat with Sam Feltham. We discuss the eternally controversial question, "is a calorie a calorie"? Like many other advocates of the low-carbohydrate diet, Feltham believes that the metabolic effects of food (particularly on insulin), rather than calorie intake per se, are the primary determinants of body fatness. I explain the perspective that my field of research has provided on this question. We also discussed why some lean people become diabetic. Feltham was a gracious host.
Nourish, Balance, Thrive with Christopher Kelly. Kelly is also an advocate of the low-carbohydrate diet for fat loss. This interview covered a lot of ground, including the insulin-obesity hypothesis, regulation of body fatness by the leptin-brain axis, how food reward works to increase calorie intake, and the impact of the food environment on food intake. I explain why I think proponents of the insulin-obesity hypothesis have mistaken association for causation, and what I believe the true relationship is between insulin biology and obesity. Kelly was also a gracious host. He provides a transcript if you'd rather read the interview in text form.
Monday, 24 November 2014
Is Meat Unhealthy? Part III
When we consider the health impacts of eating meat, cardiovascular disease is the first thing that comes to mind. Popular diet advocates often hold diametrically opposed views on the role of meat in cardiovascular disease. Even among researchers and public health officials, opinions vary. In this post, I'll do my best to sort through the literature and determine what the weight of the evidence suggests.
Ancel Keys and the Seven Countries Study
Ancel Keys was one of the first researchers to contribute substantially to the study of the link between diet and cardiovascular disease. Sadly, there is a lot of low-quality information circulating about Ancel Keys and his research (1). The truth is that Keys was a pioneering researcher who conducted some of the most impressive nutritional science of his time. The military "K ration" was designed by Keys, much of what we know about the physiology of starvation comes from his detailed studies during World War II, and he was the original Mediterranean Diet researcher. Science marches on, and not all discoveries are buttressed by additional research, but Keys' work was among the best of his day and must be taken seriously.
One of Keys' earliest contributions to the study of diet and cardiovascular disease appeared in an obscure 1953 paper titled "Atherosclerosis: A Problem in Newer Public Health" (2). This paper is worth reading if you get a chance (freely available online if you poke around a bit). He presents a number of different arguments and supporting data, most of which are widely accepted today, but one graph in particular has remained controversial. This graph shows the association between total fat intake and heart disease mortality in six countries. Keys collected the data from publicly available databases on global health and diet:
Read more »
Ancel Keys and the Seven Countries Study
Ancel Keys was one of the first researchers to contribute substantially to the study of the link between diet and cardiovascular disease. Sadly, there is a lot of low-quality information circulating about Ancel Keys and his research (1). The truth is that Keys was a pioneering researcher who conducted some of the most impressive nutritional science of his time. The military "K ration" was designed by Keys, much of what we know about the physiology of starvation comes from his detailed studies during World War II, and he was the original Mediterranean Diet researcher. Science marches on, and not all discoveries are buttressed by additional research, but Keys' work was among the best of his day and must be taken seriously.
One of Keys' earliest contributions to the study of diet and cardiovascular disease appeared in an obscure 1953 paper titled "Atherosclerosis: A Problem in Newer Public Health" (2). This paper is worth reading if you get a chance (freely available online if you poke around a bit). He presents a number of different arguments and supporting data, most of which are widely accepted today, but one graph in particular has remained controversial. This graph shows the association between total fat intake and heart disease mortality in six countries. Keys collected the data from publicly available databases on global health and diet:
Read more »
Monday, 27 October 2014
Is Meat Unhealthy? Part II
In the last post, I said Part II would be about cardiovascular disease. Shortly after publishing that, I realized that before we move on to diseases, we need to set the stage by considering our evolutionary history with meat. So here we go.
Human Evolutionary History with Meat: 200 to 2.6 Million Years Ago
Mammals evolved from ancestral therapsids approximately 220 million years ago (Richard Klein. The Human Career. 2009). Roughly 100 million years ago, placental mammals emerged. The earliest placental mammals are thought to have been nocturnal shrew-like beasts that subsisted primarily on insects, similar to modern shrews and moles. Mammalian teeth continued to show features specialized for insect consumption until the rise of the primates.
65 million years ago, coinciding with the evolution of the first fruiting plants, our ancestors took to the trees and became primates. For most of the time between then and now, our ancestors likely ate the prototypical primate diet of fruit, seeds, leaves/stems, and insects (1). Some primates also hunt smaller animals and thus eat the flesh of mammals, birds, reptiles, amphibians, and fish in addition to insects. However, the contribution of non-insect meat to the diet is usually small.
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Human Evolutionary History with Meat: 200 to 2.6 Million Years Ago
Mammals evolved from ancestral therapsids approximately 220 million years ago (Richard Klein. The Human Career. 2009). Roughly 100 million years ago, placental mammals emerged. The earliest placental mammals are thought to have been nocturnal shrew-like beasts that subsisted primarily on insects, similar to modern shrews and moles. Mammalian teeth continued to show features specialized for insect consumption until the rise of the primates.
65 million years ago, coinciding with the evolution of the first fruiting plants, our ancestors took to the trees and became primates. For most of the time between then and now, our ancestors likely ate the prototypical primate diet of fruit, seeds, leaves/stems, and insects (1). Some primates also hunt smaller animals and thus eat the flesh of mammals, birds, reptiles, amphibians, and fish in addition to insects. However, the contribution of non-insect meat to the diet is usually small.
Read more »
Friday, 24 October 2014
Tuesday, 21 October 2014
Is Meat Unhealthy? Part I
Introduction
At Dr. McDougall's Advanced Study Weekend, I had the opportunity to hear a number of researchers and advocates make the case for a "plant-based diet", which is a diet containing little or no animal foods. Many of them voiced the opinion that animal foods contribute substantially to the primary killers in the US, such as heart disease and cancer. Some of the evidence they presented was provocative and compelling, so it stimulated me to take a deeper look and come to my own conclusions.
No matter what the health implications of meat eating turn out to be, I respect vegetarians and vegans. Most of them are conscientious, responsible people who make daily personal sacrifices to try to make the world a better place for all of us.
My Experience with Vegetarian and Vegan Diets
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At Dr. McDougall's Advanced Study Weekend, I had the opportunity to hear a number of researchers and advocates make the case for a "plant-based diet", which is a diet containing little or no animal foods. Many of them voiced the opinion that animal foods contribute substantially to the primary killers in the US, such as heart disease and cancer. Some of the evidence they presented was provocative and compelling, so it stimulated me to take a deeper look and come to my own conclusions.
No matter what the health implications of meat eating turn out to be, I respect vegetarians and vegans. Most of them are conscientious, responsible people who make daily personal sacrifices to try to make the world a better place for all of us.
My Experience with Vegetarian and Vegan Diets
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Tuesday, 14 October 2014
Obesity → Diabetes
A new study adds to the evidence that the prevalence of type 2 diabetes is rapidly increasing in the US, and our national weight problem is largely to blame.
The Centers for Disease Control (CDC) currently estimates that a jaw-dropping 33 percent of US men, and 39 percent of US women, will develop diabetes at some point in their lives (1). Roughly one out of three people in this country will develop diabetes, and those who don't manage it effectively will suffer debilitating health consequences. Has the risk of developing diabetes always been so high, and if not, why is it increasing?
In the same issue of the Annals of Internal Medicine as the low-carb vs. low-fat study, appears another study that aims to partially address this question (2).
Read more »
The Centers for Disease Control (CDC) currently estimates that a jaw-dropping 33 percent of US men, and 39 percent of US women, will develop diabetes at some point in their lives (1). Roughly one out of three people in this country will develop diabetes, and those who don't manage it effectively will suffer debilitating health consequences. Has the risk of developing diabetes always been so high, and if not, why is it increasing?
In the same issue of the Annals of Internal Medicine as the low-carb vs. low-fat study, appears another study that aims to partially address this question (2).
Read more »
Friday, 10 October 2014
Wednesday, 1 October 2014
Metabolic Effects of a Traditional Asian High-carbohydrate Diet
A recent study supports the notion that an 'ancestral diet' focused around high-starch agricultural foods can cultivate leanness and metabolic health.
John McDougall gave Christopher Gardner a hard time at the McDougall Advanced Study Weekend. Dr. Gardner conducts high-profile randomized controlled trials (RCTs) at Stanford to compare the effectiveness of a variety of diets for weight loss, cardiovascular and metabolic health. The "A to Z Study", in which Atkins, Zone, Ornish, and LEARN diets were pitted against one another for one year, is one of his best-known trials (1).
Dr. McDougall asked a simple question: why haven't these trials evaluated the diet that has sustained the large majority of the world's population for the last several thousand years? This is an agriculturalist or horticulturalist diet based around starchy foods such as grains, tubers, legumes, and plantains, and containing little fat or animal foods. Researchers have studied a number of cultures eating this way, and have usually found them to be lean, with good cardiovascular and metabolic health. Why not devote resources to studying this time-tested ancestral diet? I think it's a fair question.
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John McDougall gave Christopher Gardner a hard time at the McDougall Advanced Study Weekend. Dr. Gardner conducts high-profile randomized controlled trials (RCTs) at Stanford to compare the effectiveness of a variety of diets for weight loss, cardiovascular and metabolic health. The "A to Z Study", in which Atkins, Zone, Ornish, and LEARN diets were pitted against one another for one year, is one of his best-known trials (1).
Dr. McDougall asked a simple question: why haven't these trials evaluated the diet that has sustained the large majority of the world's population for the last several thousand years? This is an agriculturalist or horticulturalist diet based around starchy foods such as grains, tubers, legumes, and plantains, and containing little fat or animal foods. Researchers have studied a number of cultures eating this way, and have usually found them to be lean, with good cardiovascular and metabolic health. Why not devote resources to studying this time-tested ancestral diet? I think it's a fair question.
Read more »
Friday, 26 September 2014
Help Advance Diabetes Research
A University of Virginia researcher named Hannah Menefee contacted me recently to ask for our help. She and her colleagues are conducting a study on how people with type 2 diabetes use Facebook to manage their health, and how that technology can be leveraged to support effective health communication.
If you have type 2 diabetes, and you'd like to participate in the study, please join their Diabetes Management Study Facebook group. There, you'll receive more information about the study, you'll receive a short survey, and you may be invited into one of the study phases.
If you have type 2 diabetes, and you'd like to participate in the study, please join their Diabetes Management Study Facebook group. There, you'll receive more information about the study, you'll receive a short survey, and you may be invited into one of the study phases.
Friday, 19 September 2014
Thursday, 18 September 2014
My AHS14 Talk on Leptin Resistance is Posted
The Ancestral Health Society just posted a video of my recent talk "What Causes Leptin Resistance?" Follow the link below to access it. Enjoy!
What Causes Leptin Resistance?
What Causes Leptin Resistance?
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