U.S. Weight, Lifestyle and Diet Trends, 1970- 2007

For this post, I compiled statistics on U.S. weight, health and lifestyle trends, and graphed them as consistently as possible. They span the period from 1970 to 2007, during which the obesity rate doubled. The data come from the National Health and Nutrition Examination Survey (NHANES), the Behavioral Risk Factor Surveillance System (BRFSS), and the U.S. Department of Agriculture (USDA). Some of the graphs are incomplete, either because the data don't exist, or because I wasn't able to find them. Obesity is defined as a body mass index (BMI) of 30+; overweight is a BMI of 25+. Yes, it's frightening. It has affected adults and children (NHANES).
The percentage of Americans who report exercising in their spare time has actually increased since 1988 (BRFSS).
We're eating about 250 more calories per day, according to NHANES.
The 250 extra calories are coming from carbohydrate (NHANES).

We're eating more vegetables and fruit (USDA).
We're eating more meat by weight, although calories from meat have probably gone down because the meat has gotten leaner (USDA). This graph represents red meat, fish and poultry. The increase comes mostly from poultry. Boneless, skinless chicken breasts anyone?
We're eating more sugar (USDA). The scale of the graph doesn't allow you to fully appreciate that sweetener consumption had increased by a full 100 calories per day by 1999, although it has dropped a bit since then. This is based on food disappearance data. In other words, the amount consumed is estimated using the amount sold domestically, minus a percentage that approximates waste. High-fructose corn syrup has seized nearly 50% of the sweetener market since 1970.
Again, the scale of the graph doesn't allow you to fully appreciate the magnitude of the change here. In 2000, we ate approximately 2.5 ounces, or 280 calories, more processed grains per day than in 1970 (USDA). That has since decreased slightly (34 calories). You might be saying to yourself right now "hey, that plus the 100 calories from sugar adds up to more of an increase than the NHANES data show!" Yes, and I think that points to the fact that the data sets are not directly comparable. NHANES data are self-reported whereas USDA data are collected from vendors. Regardless of the absolute numbers, our processed grain consumption has gone way up since 1970.

Wheat is still king. Although we grow a lot of corn in this country, most of it gets fed to animals. We prefer eating wheat without first feeding it to an intermediary. In absolute quantity, wheat consumption has increased more than any other grain (not including corn syrup).
Bye bye whole milk. Hello skim milk (USDA).

This graph represents "added fats", as opposed to fats that occur naturally in meat or milk (the USDA does not track the latter). Added fats include salad oil, cooking oil, deep fry oil, butter, lard, tallow, etc. We are eating a lot more vegetable oil than we were in 1970. It comes chiefly from the industrial, omega-6 rich oils such as soybean, corn and canola. Added animal fats have increased slightly, but it's pretty insignificant in terms of calories.

There is an artifact in this graph that I have to point out. In 2000, the USDA changed the way it gathered vegetable oil data. This led to an abrupt, apparent increase in its consumption that is obvious on the graph. So it's difficult to make any quantitative conclusions, but I think it's clear nevertheless that vegetable oil intake has increased considerably.

Between 1970 and 1980, something changed in the U.S. that caused a massive increase in obesity and other health problems. Some combination of factors reached a critical mass that our metabolism could no longer tolerate. The three biggest changes in the American diet since 1970:

• An increase in cereal grain consumption, particularly wheat.
• An increase in sweetener consumption
• The replacement of meat and milk fat with industrial vegetable oils, with total fat intake remaining the same.

Mainstream America has done to itself what it did to native American and other indigenous cultures worldwide, with the same result.

U.S. Weight, Lifestyle and Diet Trends, 1970- 2007

For this post, I compiled statistics on U.S. weight, health and lifestyle trends, and graphed them as consistently as possible. They span the period from 1970 to 2007, during which the obesity rate doubled. The data come from the National Health and Nutrition Examination Survey (NHANES), the Behavioral Risk Factor Surveillance System (BRFSS), and the U.S. Department of Agriculture (USDA). Some of the graphs are incomplete, either because the data don't exist, or because I wasn't able to find them. Obesity is defined as a body mass index (BMI) of 30+; overweight is a BMI of 25+. Yes, it's frightening. It has affected adults and children (NHANES).
The percentage of Americans who report exercising in their spare time has actually increased since 1988 (BRFSS).
We're eating about 250 more calories per day, according to NHANES.
The 250 extra calories are coming from carbohydrate (NHANES).

We're eating more vegetables and fruit (USDA).
We're eating more meat by weight, although calories from meat have probably gone down because the meat has gotten leaner (USDA). This graph represents red meat, fish and poultry. The increase comes mostly from poultry. Boneless, skinless chicken breasts anyone?
We're eating more sugar (USDA). The scale of the graph doesn't allow you to fully appreciate that sweetener consumption had increased by a full 100 calories per day by 1999, although it has dropped a bit since then. This is based on food disappearance data. In other words, the amount consumed is estimated using the amount sold domestically, minus a percentage that approximates waste. High-fructose corn syrup has seized nearly 50% of the sweetener market since 1970.
Again, the scale of the graph doesn't allow you to fully appreciate the magnitude of the change here. In 2000, we ate approximately 2.5 ounces, or 280 calories, more processed grains per day than in 1970 (USDA). That has since decreased slightly (34 calories). You might be saying to yourself right now "hey, that plus the 100 calories from sugar adds up to more of an increase than the NHANES data show!" Yes, and I think that points to the fact that the data sets are not directly comparable. NHANES data are self-reported whereas USDA data are collected from vendors. Regardless of the absolute numbers, our processed grain consumption has gone way up since 1970.

Wheat is still king. Although we grow a lot of corn in this country, most of it gets fed to animals. We prefer eating wheat without first feeding it to an intermediary. In absolute quantity, wheat consumption has increased more than any other grain (not including corn syrup).
Bye bye whole milk. Hello skim milk (USDA).

This graph represents "added fats", as opposed to fats that occur naturally in meat or milk (the USDA does not track the latter). Added fats include salad oil, cooking oil, deep fry oil, butter, lard, tallow, etc. We are eating a lot more vegetable oil than we were in 1970. It comes chiefly from the industrial, omega-6 rich oils such as soybean, corn and canola. Added animal fats have increased slightly, but it's pretty insignificant in terms of calories.

There is an artifact in this graph that I have to point out. In 2000, the USDA changed the way it gathered vegetable oil data. This led to an abrupt, apparent increase in its consumption that is obvious on the graph. So it's difficult to make any quantitative conclusions, but I think it's clear nevertheless that vegetable oil intake has increased considerably.

Between 1970 and 1980, something changed in the U.S. that caused a massive increase in obesity and other health problems. Some combination of factors reached a critical mass that our metabolism could no longer tolerate. The three biggest changes in the American diet since 1970:

• An increase in cereal grain consumption, particularly wheat.
• An increase in sweetener consumption
• The replacement of meat and milk fat with industrial vegetable oils, with total fat intake remaining the same.

Mainstream America has done to itself what it did to native American and other indigenous cultures worldwide, with the same result.

The Myth of the High-Protein Diet

The phrase "low-carbohydrate diet" is a no-no in some circles, because it implies that a diet is high in fat. Often, the euphemism "high-protein diet" is used to avoid the mental image of a stick of butter wrapped in bacon. It's purely a semantic game, because there is no such thing as a diet in which the majority of calories come from protein. The ability of the human body to metabolize protein ends at about 1/3 of calories (1, 2), and the long-term optimum may be lower still. Low-carbohydrate diets (yes, the ones that are highly effective for weight loss and general health) are high-fat diets.

Healthy cultures around the world tend to consume roughly 10 to 20% of calories from protein:

Masai - 19%

Kitava - 10%

Tokelau - 12%

Inuit - 20%, according to Stefansson

Kuna - 12%

Sweden - 12%

United States - 15%

Human milk - 6%

The balance comes from fat and carbohydrate. Ask a traditional Inuit. If there's no fat on your meat, you may as well starve. Literally. "Rabbit starvation" was a term coined by American explorers who quickly realized that living on lean game is somewhere between unhealthy and fatal.

In the early 1900s, anthropologist and explorer Vilhjalmur Stefansson lived for several years among completely isolated Canadian Inuit (Eskimo) who had never seen a white person before. They were literally a stone-age culture, completely uninfluenced by the modern world. They are representative of how some of our paleolithic ancestors would have lived. Here's Stefansson, quoted from My Life With the Eskimo (1913):

In certain places and in certain years, rabbits are an important article of diet, but even when there is an abundance of this animal, the Indians consider themselves starving if they get nothing else, - and fairly enough, as my own party can testify, for any one who is compelled in winter to live for a period of several weeks on lean meat will actually starve, in this sense: that there are lacking from his diet certain necessary elements, notably fat, and it makes no difference how much he eats, he will be hungry at the end of each meal, and eventually he will lose strength or become actually ill. The Eskimo who have provided themselves in summer with bags of seal oil can carry them into a rabbit country and can live on rabbits satisfactorily for months.

Dr. Loren Cordain, in his excellent paper "Plant-Animal Subsistence Ratios and Macronutrient Energy Estimations in Worldwide Hunter-Gatherer Diets", argues based on calculated estimates that historical hunter-gatherers generally consumed between 19 and 35% of calories from protein:

This high reliance on animal-based foods coupled with the relatively low carbohydrate content of wild plant foods produces universally characteristic macronutrient composition ratios in which protein is elevated (19- 35% of energy) at the expense of carbohydrates (22- 40% of energy).

Later, he states that the most plausible range of fat intakes is 28- 58%. I agree with his assertion that hunter-gatherer diets tended to be relatively high in protein compared with contemporary diets, but I think his protein numbers are a bit high. Why? Because he calculates macronutrient composition based on the whole-carcass fat content of "representative" animals such as deer.

It's clear from the anthropological literature that hunter-gatherers did not go after representative animals. They went after the fattest animals they could find. They knew exactly which animals were fattest in which seasons, which individuals were likely to be fattest within a herd, and which bodyparts were fattest on an individual animal. For example, Stefansson describes how the Inuit relied on (extremely fat) seal in the spring, wolf in the summer, and caribou and bear in the fall and early winter. If necessary, they would discard lean meat in favor of tongue, marrow, internal organs, back fat and other fat-rich bodyparts. This was in order to obtain a minimum of 65% of calories from fat.

Hunter-gatherers would sometimes even provision themselves with enough fat in advance to last a lean season or two. This was true for dozens of tribes along the Northwest coast of North America that relied chiefly on animal foods. Here's another excerpt from My Life With the Eskimo:

...[spring] is the season which the Eskimo give up to the accumulation of blubber for the coming year. Fresh oil is not nearly so palatable or digestible as oil that has been allowed to ferment in a sealskin bag through the summer, and besides that it is difficult often to get seals in the fall... Each family will in the spring be able to lay away from three to seven bags of oil. Such a bag consists of the whole skin of the common seal... This makes a bag which will hold about three hundred pounds of blubber, so that a single family's store of oil for the fall will run from nine hundred to two thousand pounds.

That's a lot of oil! Some of it would have been used to light oil lamps, but much of it would have been eaten. I think Cordain's estimate of the protein intake of hunter-gatherers is a bit high due to his underestimating fat intake. His paper shows that if you break historical hunter-gatherer cultures into 10 groups based on their reliance on animal foods, the most numerous group (46 out of 229) obtained 85- 100% of their food from animal sources. In other words, approximately 20% of historical hunter-gatherers were carnivorous or nearly so. If the human protein ceiling is 35% of calories, that means roughly one fifth of hunter-gatherers ate 65% or more of their calories as fat. It also means carnivory and high-fat diets are not just anomalies, they are part of the human ecological niche. Zero out of 229 groups obtained less than 16% of calories from animal foods. Vegetarianism is not part of our niche.

Further, although the human body can theoretically tolerate up to 35% protein by calories, even that amount is probably not optimal in the long term. I think that's suggested by the fact that diverse cultures tend to find a source of fat and/or carbohydrate that keeps their protein intake roughly between 10 and 20%. I think it's fine to eat plenty of protein, and there's no need to deliberately restrict it, because your tastes will tell you if you're eating too much. However, "high-protein diet" as a euphemism for low-carbohydrate diet is a misnomer. Low-carbohydrate diets are, and have always been, high-fat diets.

The Myth of the High-Protein Diet

The phrase "low-carbohydrate diet" is a no-no in some circles, because it implies that a diet is high in fat. Often, the euphemism "high-protein diet" is used to avoid the mental image of a stick of butter wrapped in bacon. It's purely a semantic game, because there is no such thing as a diet in which the majority of calories come from protein. The ability of the human body to metabolize protein ends at about 1/3 of calories (1, 2), and the long-term optimum may be lower still. Low-carbohydrate diets (yes, the ones that are highly effective for weight loss and general health) are high-fat diets.

Healthy cultures around the world tend to consume roughly 10 to 20% of calories from protein:

Masai - 19%

Kitava - 10%

Tokelau - 12%

Inuit - 20%, according to Stefansson

Kuna - 12%

Sweden - 12%

United States - 15%

Human milk - 6%

The balance comes from fat and carbohydrate. Ask a traditional Inuit. If there's no fat on your meat, you may as well starve. Literally. "Rabbit starvation" was a term coined by American explorers who quickly realized that living on lean game is somewhere between unhealthy and fatal.

In the early 1900s, anthropologist and explorer Vilhjalmur Stefansson lived for several years among completely isolated Canadian Inuit (Eskimo) who had never seen a white person before. They were literally a stone-age culture, completely uninfluenced by the modern world. They are representative of how some of our paleolithic ancestors would have lived. Here's Stefansson, quoted from My Life With the Eskimo (1913):

In certain places and in certain years, rabbits are an important article of diet, but even when there is an abundance of this animal, the Indians consider themselves starving if they get nothing else, - and fairly enough, as my own party can testify, for any one who is compelled in winter to live for a period of several weeks on lean meat will actually starve, in this sense: that there are lacking from his diet certain necessary elements, notably fat, and it makes no difference how much he eats, he will be hungry at the end of each meal, and eventually he will lose strength or become actually ill. The Eskimo who have provided themselves in summer with bags of seal oil can carry them into a rabbit country and can live on rabbits satisfactorily for months.

Dr. Loren Cordain, in his excellent paper "Plant-Animal Subsistence Ratios and Macronutrient Energy Estimations in Worldwide Hunter-Gatherer Diets", argues based on calculated estimates that historical hunter-gatherers generally consumed between 19 and 35% of calories from protein:

This high reliance on animal-based foods coupled with the relatively low carbohydrate content of wild plant foods produces universally characteristic macronutrient composition ratios in which protein is elevated (19- 35% of energy) at the expense of carbohydrates (22- 40% of energy).

Later, he states that the most plausible range of fat intakes is 28- 58%. I agree with his assertion that hunter-gatherer diets tended to be relatively high in protein compared with contemporary diets, but I think his protein numbers are a bit high. Why? Because he calculates macronutrient composition based on the whole-carcass fat content of "representative" animals such as deer.

It's clear from the anthropological literature that hunter-gatherers did not go after representative animals. They went after the fattest animals they could find. They knew exactly which animals were fattest in which seasons, which individuals were likely to be fattest within a herd, and which bodyparts were fattest on an individual animal. For example, Stefansson describes how the Inuit relied on (extremely fat) seal in the spring, wolf in the summer, and caribou and bear in the fall and early winter. If necessary, they would discard lean meat in favor of tongue, marrow, internal organs, back fat and other fat-rich bodyparts. This was in order to obtain a minimum of 65% of calories from fat.

Hunter-gatherers would sometimes even provision themselves with enough fat in advance to last a lean season or two. This was true for dozens of tribes along the Northwest coast of North America that relied chiefly on animal foods. Here's another excerpt from My Life With the Eskimo:

...[spring] is the season which the Eskimo give up to the accumulation of blubber for the coming year. Fresh oil is not nearly so palatable or digestible as oil that has been allowed to ferment in a sealskin bag through the summer, and besides that it is difficult often to get seals in the fall... Each family will in the spring be able to lay away from three to seven bags of oil. Such a bag consists of the whole skin of the common seal... This makes a bag which will hold about three hundred pounds of blubber, so that a single family's store of oil for the fall will run from nine hundred to two thousand pounds.

That's a lot of oil! Some of it would have been used to light oil lamps, but much of it would have been eaten. I think Cordain's estimate of the protein intake of hunter-gatherers is a bit high due to his underestimating fat intake. His paper shows that if you break historical hunter-gatherer cultures into 10 groups based on their reliance on animal foods, the most numerous group (46 out of 229) obtained 85- 100% of their food from animal sources. In other words, approximately 20% of historical hunter-gatherers were carnivorous or nearly so. If the human protein ceiling is 35% of calories, that means roughly one fifth of hunter-gatherers ate 65% or more of their calories as fat. It also means carnivory and high-fat diets are not just anomalies, they are part of the human ecological niche. Zero out of 229 groups obtained less than 16% of calories from animal foods. Vegetarianism is not part of our niche.

Further, although the human body can theoretically tolerate up to 35% protein by calories, even that amount is probably not optimal in the long term. I think that's suggested by the fact that diverse cultures tend to find a source of fat and/or carbohydrate that keeps their protein intake roughly between 10 and 20%. I think it's fine to eat plenty of protein, and there's no need to deliberately restrict it, because your tastes will tell you if you're eating too much. However, "high-protein diet" as a euphemism for low-carbohydrate diet is a misnomer. Low-carbohydrate diets are, and have always been, high-fat diets.

Gluten Sensitivity: Celiac Disease is the Tip of the Iceberg

Celiac disease is a degeneration of the lining of the small intestine caused by a sensitivity to gluten. Gluten is the protein portion of wheat, rye, barley, and wheat relatives (spelt, kamut, emmer, einkorn and triticale). I found an interesting paper recently on the impact of celiac disease on nutrient status and bone density. Researchers compared 54 Northern Italian children with untreated celiac disease to 60 presumably healthy children. The celiac patients had extremely poor vitamin D status, with a deficiency rate of 35.18% compared to 5% in the control group. This was using the lenient cut-off point of 20 ng/mL. Average serum 25(OH)D3 in celiac patients was less than half the level of the control group. The celiac patients also had low serum calcium and magnesium, and elevated parathyroid hormone. Celiac children had lower bone mineral density. All parameters returned to normal after 6 months on a gluten-free diet.

This confirms what has been shown numerous times before: celiac disease interferes with nutrient status, including the all-important fat-soluble vitamins. It's not surprising, since it flattens the villi, finger-like structures necessary for efficient nutrient absorption in the small intestine. But wait, the overwhelming majority of our vitamin D comes from the effect of sunlight on our skin, not through our small intestine! So gluten sensitivity must be doing something besides just flattening villi. Perhaps it does. Feeding wheat bran to "healthy" volunteers caused them to burn through their vitamin D reserves at an accelerated rate. I think this underlines what I've come to believe about wheat: it's problematic for a large proportion of the population, perhaps the majority.

Approximately 12% of Americans can be diagnosed as gluten sensitive using blood antibody tests (anti-gliadin IgA or IgG). A subset of these have full-blown celiac disease. The vast, vast majority are undiagnosed. Gluten sensitivity associates with a dizzying array of diseases, including autoimmune disorders, cancer, and neurological problems. The problem with the blood tests is they aren't very sensitive. The most common blood tests for celiac disease look for a class of antibody called IgA. IgA is produced by the mucosa, including the gut. Unless gut damage is already extensive, the majority of IgA stays in the gut. This may cause the assay to overlook many cases of gluten sensitivity. A negative blood antibody test does not rule out gluten sensitivity!

I recently discovered the work of Dr. Kenneth Fine of EnteroLab. He has developed an assay that detects anti-gliadin IgA in stool. Gliadin is one of the problematic proteins in gluten that is implicated in gluten sensitivity. Dr. Fine has been conducting informal research using his fecal anti-gliadin IgA test (data here). He has found that:

• 100% of untreated celiac patients are antigliadin IgA positive by fecal test, compared to only 76% by blood (n= 17).
• 76% of microscopic colitis (a type of chronic diarrhea) patients are positive by the fecal test, compared to 9% by blood (n= 57).
• 57% of symptomatic people (digestive problems?) are positive by the fecal test, compared to 12% by blood (n= 58).
• 62% of people with autoimmune disease are positive by the fecal test.
• 29% of asymptomatic (healthy) people are positive by the fecal test, compared to 11-12% by blood (n= 240).
• Baby and cow feces are 0% positive by the stool assay.

It gets worse. Gluten sensitivity is determined in large part by genetics. A gene called HLA-DQ is intimately involved. It encodes a protein that is expressed on the surface of cells, that serves to activate immune cells when certain foreign substances are present. Different versions of the gene are activated by different substances. HLA-DQ2 and HLA-DQ8 are classically associated with celiac disease. Roughly 42% of the US population carries DQ2 or DQ8. According to Dr. Fine, every allele except DQ4 has some association with gluten-related problems! Only 0.4% of the U.S. population carries HLA-DQ4 and no other allele.

Not everyone who is genetically susceptible will end up developing health problems due to gluten, but it's impossible to estimate how many of the problems we attribute to other causes are in fact caused or exacerbated by gluten.

The immune system can be divided into two parts: innate and adaptive. The innate immune system is a nonspecific, first-line reaction to a perceived threat. The adaptive immune system is a more sophisticated, but slower system that produces a powerful response by particular cell types to a very specific threat. Antibody production is part of the adaptive immune system. Thus, if your gluten sensitivity test is looking for antibodies, it could still be missing an immune reaction to gluten mediated by the innate immune system!

This question has been addressed in a preliminary study. Researchers took gut biopsies from celiac patients and asymptomatic controls. Five out of six asymptomatic controls showed elevated interleukin-15, a marker of innate immune activation, upon exposure to gliadin. An activated innate immune system (commonly called 'inflammation') is associated with a wide array of chronic diseases, from obesity to cancer to cardiovascular disease. Inflammatory cytokines are elevated in celiac patients and may play a role in their bone pathology. What I would like to see is some negative controls-- would the gut biopsies have produced interleukin-15 in response to benign foods or is it truly specific to gluten?

I don't intend to imply that everyone has gluten sensitivity, but I do think the totality of the data are thought-provoking. They also include the association between the introduction of wheat to non-industrial populations and the development of widespread health problems. Another thing to keep in mind is that traditional sourdough fermentation breaks down a portion of gluten, possibly explaining the rise in gluten sensitivity that has paralleled a shift to quick-rise yeast breads. I believe that gluten sensitivity is behind many modern ills, and should be on the short list of suspects in the case of unexplained health problems. This is particularly true of digestive, autoimmune and neurological disorders. Gluten sensitivity is easy to address: stop eating gluten for a few weeks. See how you feel. Reintroduce gluten and see what happens. You might learn something about yourself.