Is Meat Unhealthy? Part VI

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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.
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Food Reward Friday

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This week's lucky "winner"... croissants!!


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Food Reward Friday

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This week's lucky winner... Cheesecake Factory carrot cake!!


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Is Meat Unhealthy? Part V

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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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Food Reward Friday

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This week's lucky "winner"... Pumpkin pie!!


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Food Reward Friday

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This week's lucky "winner"... Pizza Hut Doritos Crunchy Crust Pizza!


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Is Meat Unhealthy? Part IV

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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).

!Kung man gathering mongongo fruit/nuts.
From The !Kung San, by Richard B. Lee.
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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Recent Interviews

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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.

Is Meat Unhealthy? Part II

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Over time, animals adapt to the foods they regularly consume.  This is how archaeologists can, for example, determine that Triceratops was an herbivore and Tyrannosaurus was a carnivore just by looking at the structure of the skeleton.  Adaptations to diet extend beyond skeletal structure, into digestion, metabolism, the brain, musculature, and other aspects of physical function.  What is our evolutionary history with meat?

Human Evolutionary History with Meat: 200 to 2.6 Million Years Ago

Mammals evolved from ancestral "mammal-like reptiles" (therapsids, then cynodonts) 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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Food Reward Friday

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This week's lucky "winner"... the pumpkin spice latte!!


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Is Meat Unhealthy? Part I

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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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Obesity → Diabetes

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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).

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Food Reward Friday

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This week's lucky "winner"... profiteroles!!


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