Is Meat Unhealthy? Part VIII

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Health can be defined as the absence of disease, and that is the lens through which we've been examining meat so far.  However, most of us have a broader view of health that also includes optimal growth and development, physical and mental performance, well-being, fertility, immunity, robustness, and resilience.  What role does meat play in this broader view of health?

Non-industrial cultures

One of the things I keep coming back to in this series is the strong natural affinity that our species has for meat.  Every culture that does not prohibit meat consumption for religious reasons (e.g., Indian Hindus) seeks and eats meat avidly.

A key fact that stands out from my recent conversations with anthropologists is that hunter-gatherers and subsistence agriculturalists place a high value on meat, even if they already have regular access to it.  Here's an excerpt from a paper by Kim Hill, Magdalena Hurtado, and colleagues (1):
Observations of the exchange rate between other foragers and their agricultural neighbors indicate that meat is worth much more than carbohydrate calories (e.g., Hart 1978; Peterson 1981). Hart, in his study of exchanges of meat and casava between Pygmy foragers and neighboring agriculturalists, found that approximately four and one half times as many calories of casava were exchanged for each calorie of meat given. In addition, it appears that almost everywhere in the world meat calories from domestic animals are probably expensive to produce relative to plant calories, and yet subsistence farmers continue to use at least some of their "cheap" plant calories to produce "expensive" animal calories (see Harris 1985 for discussion)
Why do humans around the globe value meat so much?  This strongly suggests that we've evolved an affinity for meat because eating it provides a reproductive advantage.  In other words, meat may increase our "Darwinian fitness".

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Food Reward Friday

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This week's lucky "winner"... the KFC Double Down Dog!!


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Is Meat Unhealthy? Part VII

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Looking at individual diseases is informative, but it can cause us to become myopic, making broad health-related decisions based on narrow information.  It can cause us to miss the forest for the trees.  In this case, the "trees" are individual diseases and the "forest" is total mortality: the overall risk of dying from any cause.  Does eating meat increase total mortality, shortening our lifespans?

Non-industrial cultures

Traditionally-living cultures such as hunter-gatherers and non-industrial agriculturalists are not the best way to answer this question, because their mean lifespans tend to be short regardless of diet.  This is due to ~30 percent infant mortality, which drags down the average, as well as a high risk of death in adulthood from infectious disease, accidents, and homicide/warfare.  It can also be difficult to accurately measure the age of such people, although there are reasonably good methods available.

However, there are semi-industrialized cultures that can help us answer this question, because they feature a somewhat traditional diet and lifestyle, combined with modern medicine and the rule of law.  The so-called Blue Zones, areas of exceptional health and longevity, fall into this category.  These include Sardinia, Italy; Okinawa, Japan; Loma Linda, California; Nicoya Peninsula, Costa Rica; and Icaria, Greece.

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Food Reward Friday

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This week's lucky "winner"... barbecue ribs!!


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Does high protein explain the low-carb "metabolic advantage"?

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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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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.