"Americans are getting used to failures by government experts. Government economists have a dismal
forecasting record. Government actions and advice during the pandemic
were often misguided. And dozens of former government intelligence
experts got the Hunter Biden laptop story wrong.
A less recognized but also important failure may be in nutrition.
Federal experts appear to have issued faulty advice for decades, even as
American obesity exploded from 15 percent in the 1970s to 42 percent today. Federal guidance on nutrition has a large influence on health practice across society. Some researchers argue that Americans have generally responded to the guidance, yet obesity has nonetheless soared.
A clue to shortcomings in federal nutrition guidance comes from calorie data. A new U.S. Department of Agriculture (USDA) study
shows that average daily calorie intake increased 21 percent from
1977–78 to 2003-04, and then started trending down. By 2017–18, calories
were up 15 percent from the 1970s, but as the study notes, “the rise in obesity rate outpaced the increase in calorie intake.”
In a 2022 article,
Professor of Nutrition Dariush Mozaffarian noted that “over the last 20
[years] we are not eating more calories, nor exercising less, but are
still becoming more obese.” As average calories have dipped, the obesity
rate rose from 31 percent in 2001–2002 to 42 percent today.
How can that be? Obesity is caused not just by the amount we eat but
also what we eat. Generally, the government advised us to emphasize
carbohydrates and deemphasize protein and fat, as shown in the food pyramid.
But some nutritionists are now saying that was backwards. As
a libertarian, I don’t want the government telling us what to eat, and
our diets may have been better if that had been the case.
Like government experts, private‐sector experts get things wrong.
But the government uses mandates and subsidies to impose its will, and
its strong positions often displace other views. In a presentation at Cato, author and science journalist Nina Teicholz
discussed the government’s flawed nutrition standards and the harm she
believes they caused. She observed, “the level of certainty you need to
have for public policy of an entire population ought to be very high,”
and federal directives on nutrition fell far short of that level.
The chart shows average daily calorie intakes of Americans, based on
the new USDA data. Carbohydrates are up 22 percent since the late 1970s,
fat is up 12 percent, and protein is unchanged. It appears that we
mainly want to look at carbs to explain the rise in obesity.
Below I excerpt from two studies that sync with Nina
Teicholz’s views about the record of faulty government advice on
protein, fats, and carbohydrates. I understand that other experts have
conflicting views. Nutrition is a complex field and scientists have not
figured it all out yet.
However, the costs of bad diets to individuals, the medical system,
and society are huge, so we should pay close attention to government
interventions. This is particularly true this year because Congress is
set to consider another large farm and food subsidy bill, which may adversely influence American diets.
First, an excerpt from a 2015 study by Evan Cohen and colleagues in Nutrition. Note that the latest USDA data show fat calories up somewhat since this study was published.
Americans in general have been following the nutrition
advice that the American Heart Association and the US Departments of
Agriculture and Health and Human Services have been issuing for more
than 40 [years]: Consumption of fats has dropped from 45% to 34% with
a corresponding increase in carbohydrate consumption from 39% to 51% of
total caloric intake. In addition, from 1971 to 2011, average weight and
body mass index have increased dramatically, with the percentage of
overweight or obese Americans increasing from 42% in 1971 to 66% in
2011.
… Since 1971, the shift in macronutrient share from fat to
carbohydrate is primarily due to an increase in absolute consumption of
carbohydrate as opposed to a change in total fat consumption. General
adherence to recommendations to reduce fat consumption has coincided
with a substantial increase in obesity.
… Since the late 1970s, the US government, following the American
Heart Association (AHA) and much of academia, has consistently
recommended lowering the dietary percentage of fat and saturated fat, as
well as the absolute levels of dietary cholesterol, based on
a theoretical link between those food components and higher risk for
coronary heart disease. This government guidance suggested that the
reduction of dietary fat would be accompanied by a concurrent increase
in the dietary share of carbohydrate. Taken together, these
recommendations were also considered to be beneficial for the prevention
of overweight and obesity, along with diabetes, cancer, and other
chronic diseases.
… In 1961, spurred by emerging medical and epidemiologic research,
the AHA issued dietary recommendations to ‘reduce the intake of total
fat, saturated fat, and cholesterol. In 1977, the US Senate Select
Committee on Nutrition and Human Needs issued Dietary Goals for the
United States, which recommended that fat consumption be reduced to 30%
of energy intake, and that carbohydrate consumption be increased to
account for 55% to 60% of energy intake.
Following this report, Dietary Guidelines for Americans, issued by
the USDA and the US Department of Health, Education and Welfare (now the
Department of Health and Human Services; DHHS) in 1980, recommended
a reduction in the consumption of the share of total macronutrients
attributable to fat and saturated fat, and a reduction in the absolute
consumption of cholesterol. To compensate, the guidelines recommended
increasing consumption of carbohydrate as a share of total calories
because “carbohydrates contain less than half the number of calories per
ounce than fats.”
During the 1980s, the federal government continued to issue reports
and recommendations encouraging Americans to limit fat consumption. In
1982, the Committee on Diet, Nutrition, and Cancer of the National
Research Council issued Interim Dietary guidelines that recommended fat
intake be lowered from 40% to 30% of total calories in the diet,
officially endorsing the AHA’s recommendations from 1961 and the Senate
committee’s recommendations from 1977. The USDA and DHHS recommendations
have remained largely unchanged since 1980. In 1992, the Food Guide
Pyramid was released, urging Americans to use fats, oils and sweets
“sparingly,” and to consume between 6 and 11 servings of bread, cereal,
rice, and pasta.
… There is a strong relationship between the increase in carbohydrate share of total intake and obesity.
… this study demonstrated that general adherence to government
dietary recommendations to decrease fat share of total dietary intake
has been accompanied by a rapid increase in obesity rates.
Second, an excerpt from a 2022 study by Joyce Lee and colleagues in Frontiers of Nutrition:
[From 1800 to 2019] processed and ultra‐processed foods
increased from <5 to >60% of foods. Large increases occurred for
sugar, white and whole wheat flour, rice, poultry, eggs, vegetable oils,
dairy products, and fresh vegetables. Saturated fats from animal
sources declined while polyunsaturated fats from vegetable oils rose.
Non‐communicable diseases (NCDs) rose over the twentieth century in
parallel with increased consumption of processed foods, including sugar,
refined flour and rice, and vegetable oils. Saturated fats from animal
sources were inversely correlated with the prevalence of NCDs.
… Ancel Keys’ Diet‐Heart Hypothesis posited that the mid‐nineteenth
century heart disease epidemic resulted from “a changing American
diet”: increased consumption of fats, especially saturated fatty acids
(SFAs), and decreased grain consumption.
… The unprocessed elements of our nineteenth century diet–animal
fats, whole fat dairy, fresh vegetables, and fresh fruits—were
progressively replaced with more processed elements, including
industrial seed oils, HFCS, and ready‐to‐eat snacks and meals. The
data do not support the widely publicized [Ancel Keys’] “changing
American diet” of increasing animal‐derived SFAs over the first
60 years of the twentieth century.
Rather, polyunsaturated fats and partially hydrogenated fats from
vegetable oils progressively replaced lard, butter, and other
animal‐derived fats. Across the twentieth century, rising rates of
obesity, diabetes, heart disease, and cancer were associated with stable
SFA consumption. Yet, large increases in sugar and refined carbohydrate
consumption and more modest increases in total calories make refined
carbohydrates and total calories more likely factors than SFA in NCD
pathogenesis.
… The increased consumption of red meat and SFAs as the cause of the
heart disease epidemic was one foundation for Keys’ Diet‐Heart
Hypothesis, strengthened by authoritative repetition, including
McGovern’s Senate Select Committee’s Dietary Goals for America (1977),
Science in the Public Interest’s (1978) monograph The Changing American
Diet, the New York Times columnist Jane Brody’s (1985) Good Food Book,
Surgeon General Koop’s Report on Nutrition and Health (1988), and the
World Health Organization’s Diet, Nutrition, and the Prevention of
Chronic Diseases (1990). However, neither the USDA nor other data
supported this narrative.
… The alleged increase in American SFA consumption in the twentieth
century was considered the cause of the dramatic rise of
non‐communicable diseases (NCDs) … [But] our findings suggest that SFAs
are unlikely to drive obesity, diabetes, or other NCDs.
… US and international agencies and medical associations strongly
supported a low‐fat/low‐SFA, high‐carbohydrate diet for everyone
over age 2 years, and through 2008, advocated sugar as healthy for
diabetics and the general population.
… Evidence supports both the roles of energy balance and refined
carbohydrates‐insulin mechanisms in obesity, with their relative roles
likely varying based on genetics and other factors.
… our findings suggest that increased sugar and refined carbohydrate
consumptions during the twentieth century in America may have played
a larger role than total calories or physical activity, although this
remains a speculation without accurate data on all variables.
Data Notes: The chart shows average daily calories for all
Americans over age two. USDA data on grams were converted to calories
using 4 grams per calorie for protein and carbohydrates and 9 grams per
calorie for fat. Using this approach, the sum of calories in the chart
matches the USDA total for 1977–78 but understates the total for 2017–18
of 2,093 calories. More on nutrition and the farm bill here and here. The Nutrition Coalition explores these issues here."