Whole Health Source is a non-profit blog managed by Dr. Stephan Guyenet, a biologist who studies the brain’s regulation of body fat levels. I have been following his blog closely for years, and if you’re a nutrition geek like me then I suggest you do the same.
A few months ago he delivered a presentation on The History of The American Diet, at Harvard Food Law Society’s TEDx conference. Here is a post where he discusses the presentation on his blog.
The presentation is available on youtube, and I found it interesting enough to write an article about it.
The video should be of interest to anyone who lives in a western society since the dietary changes have been similar.
Here I am going to outline what I think are the key elements in his presentation.
The main theme is that the nation shifted from eating simple, home cooked meals to eating commercially prepared and packaged foods.
Increase in Obesity
In the year 1892 (120 years ago) the prevalence of obesity in the United States was less than 4% in the age groups 40-69. In the year 2000, this number was up to 25% for those 40-49 years old and almost 40% for the ages 60-69.
In the 20th century, and the past few decades specifically, obesity has reached epidemic proportions.
Changes in Food Preparation
In the 1800s, almost everyone lived near farms. The food choice was rather restricted and seasonal. Cooking, as well as the harvesting of food, was fairly labour intensive.
In the year 1920, gas and electric stoves and electric refrigerators emerged, and around this time grocery stores started popping up everywhere.
With this development followed a diversification in the diet, as well as the appearance of commercially prepared foods (processed foods).
Wheat flour consumption declined in the 20th century, being replaced by sugar, dairy, vegetables and poultry. It started increasing again around 1970, mostly in the form of processed foods.
During the 20th century, wheat consumption shifted dramatically from foods being prepared and eaten in home to processed foods.
Total potato consumption increased slightly from the years 1960 to 2007, mainly in the form of french fries and potato chips.
Consumption of fresh potatoes declined by 50%.
The Change in Fat Sources
In 1909, the main added fats in the diet were butter and lard (mainly saturated fats), and declined dramatically in the next 100 years to be replaced by margarine, shortening and refined seed oils.
The total consumption of added fats increased considerably.
Saturated fat consumption has remained relatively stable (4% increase) while monounsaturated fat has increased by 64% and polyunsaturated fat by 200% (there is an error on the slide where it says 300%).
This is reflected in the amount of linoleic acid (the predominant polyunsaturated fat in refined seed oils) in body fat stores, which has increased from 8% to about 20%. These changes are also seen in breast milk composition.
From 1909, carbohydrate consumption decreased until the year 1980, when it started increasing again.
Fat consumption increased modestly. Protein has increased slightly but remained relatively stable.
As a proportion of total calories, the only macronutrient that has increased from the years 1909 until 2009 is fat, mainly in the form of refined seed oils.
Fat has increased from 31% to 41%, while carbohydrates have decreased from 57% to 49%.
Sugar and Sweetened Beverages
Sugar consumption has increased dramatically. In 1822, the average American consumed less than 10 pounds per year, while in the year 2000 it had increased to 100 pounds per year.
As Stephan says, in 1822 we consumed an amount equal to one 12oz can of cola every 5 days, while today we consume the equivalent of one 12oz can of cola every 7 hours.
Soda vending machines appeared around the year 1920, while the replacement of sugar for High Fructose Corn Syrup happened around 1970.
Much of the increase in sugar intake has been driven by an increase in sweetened beverage consumption, which has increased five-fold from 1947 until 2005.
Engineered Hyperpalatable Foods
Stephan shows a slide with the ingredients list of a typical fast food strawberry milkshake, with a ridiculous amount of chemicals added as “artificial flavour”.
This is a typical food engineered by chemists to maximize palatability, maximize likelihood of repeat purchase, and minimize production cost.
A Major Increase in Calorie Consumption
Calorie intake has increased by 20% or 425kcal/day since the year 1970. Sources vary on this, but everyone agrees that there has been a major increase.
Calories began increasing rapidly in 1980, which corresponds with the dramatic increase in the prevalence of obesity and related problems.
The major takeaway points here are the major shift from simple home-cooked foods towards commercially prepared foods, followed by a massive increase in calorie consumption.
Regarding specific ingredients, the most striking is the massive increase in sugar and refined seed oils.