Nina Teicholz, author of The Big Fat Surprise, has spent years investigating the scientific basis for the U.S. Dietary Guidelines, particularly the longstanding recommendations to reduce saturated fat.
She questions the scientific foundation of these recommendations, including their treatment of saturated fat and dietary cholesterol, and argues that they contributed to decades of advice favoring low-fat diets over low-carb diets.
Teicholz is also critical of the heavy reliance on observational nutrition studies, which can identify associations but cannot by themselves establish cause and effect.
Her work is controversial. Many nutrition and cardiovascular experts continue to recommend limiting saturated fat. But Teicholz has helped reopen an important debate about how nutritional recommendations become established and how strong the evidence should be before they become national policy.
I found her arguments persuasive and thought this was a good place to begin.
The U.S. Dietary Guidelines were first introduced in 1980 by the Department of Agriculture (USDA) and the Department of Health and Human Services (HHS). They were intended to provide science-based recommendations to promote health and reduce the risk of chronic disease.
Among their most influential recommendations was advice to reduce saturated fat and dietary cholesterol.
These recommendations were largely influenced by early epidemiological studies, such as the Seven Countries Study led by Ancel Keys, which suggested a link between saturated fat, cholesterol, & heart disease.
Teicholz argues that these guidelines were established prematurely, based on incomplete & flawed data. She contends that subsequent research has failed to demonstrate a causal relationship between saturated fat and heart disease. Instead, she suggests that these recommendations have been driven more by political and economic interests than by robust scientific evidence.
She contends that nutrition policy subsequently became resistant to evidence that challenged the prevailing view.
One of Teicholz’s primary criticisms is the demonization of saturated fat. She highlights that the evidence supporting its role in heart disease is far less robust than commonly believed. For instance, she points to meta-analyses and systematic reviews that show no significant association between saturated fat intake and cardiovascular disease. These studies challenge the foundational premise of the dietary guidelines, raising questions about their scientific rigor.
Teicholz contends that the emphasis on low-fat diets has coincided with a rise in obesity, diabetes, and other chronic diseases. When fat is removed from food products, it is often replaced with sugar and refined carbohydrates to maintain palatability. This shift, she argues, has contributed to a dietary landscape that promotes metabolic dysfunction.
She cites research showing that diets higher in fat, particularly those including healthy fats, can improve biomarkers of health such as HDL cholesterol, triglycerides, and insulin sensitivity. These findings challenge the long-standing notion that reducing total fat intake is inherently beneficial.
The subject remains controversial.
Major cardiovascular and nutrition organizations continue to recommend limiting saturated fat, particularly when it is replaced with unsaturated fats. They point to evidence that saturated fat raises LDL cholesterol. They claim that elevated LDL-containing particles contribute to atherosclerotic cardiovascular disease.
Teicholz argues that the evidence doesn't justify the broad dietary restrictions that have been recommended for decades. And other researchers reject the fear of fat and the concerns about high LDL..
The disagreement illustrates an important theme running throughout her work: How certain should we be before nutritional hypotheses become national policy?
Teicholz also critiques the reliance on observational studies, which can show correlations but not causation. She argues that many of the studies used to support the guidelines suffer from methodological flaws, such as confounding variables and recall bias. For example, populations with high saturated fat consumption often differ in other lifestyle factors, such as smoking rates or physical activity levels, making it difficult to isolate the effects of diet.
Dietary studies face another difficulty: accurately determining what people actually eat.
Researchers often depend on questionnaires asking participants to remember foods and quantities consumed days, months, or even years earlier.
Teicholz argues that randomized controlled trials should receive greater weight when dietary recommendations are developed.
As Americans were encouraged to reduce fat, the food industry produced thousands of products marketed as "low-fat" or "fat-free."
Removing fat didn't make these foods healthier.
Many contained substantial amounts of sugar, refined flour, and other highly processed carbohydrates.
Teicholz argues that the emphasis on reducing dietary fat unintentionally encouraged greater consumption of refined carbohydrates and ultra-processed foods.
Obesity and Type 2 diabetes increased dramatically during the decades that followed.
That timing doesn't prove that low-fat recommendations caused these epidemics. Many aspects of American life changed simultaneously.
But Teicholz believes the experience provides reason to question whether the dietary advice produced the benefits policymakers expected.
The guidelines’ historical stance on dietary cholesterol—advising limits on foods like eggs and shellfish—is another area of contention. Teicholz points to studies indicating that dietary cholesterol has little effect on blood cholesterol levels for most individuals. Indeed, the 2015–2020 Dietary Guidelines acknowledged this, removing the specific cholesterol limit. However, Teicholz criticizes the lack of broader acknowledgment of the harm caused by decades of misleading advice.
For Teicholz, this history illustrates how nutritional recommendations once presented with considerable confidence can later change as the evidence develops.
Teicholz also scrutinizes the role of political and economic forces in shaping the guidelines. She argues that food industry lobbying, particularly by producers of low-fat and processed foods, has influenced the recommendations. Additionally, she highlights the inherent conflict of interest in having the USDA, which also promotes agricultural products, oversee the guidelines. This dual mandate, she suggests, compromises the objectivity of the recommendations.
The process of creating the guidelines has also faced criticism for its lack of transparency and inclusivity. Teicholz has called for greater scrutiny of the Dietary Guidelines Advisory Committee (DGAC), which she believes relies too heavily on outdated and selective evidence. Her advocacy for a more evidence-based approach has led to calls for reform in how the guidelines are developed.
Teicholz’s critique underscores the importance of reassessing the dietary guidelines, as these recommendations influence not only individual choices but also institutional policies. Schools, hospitals, and government nutrition programs like SNAP and WIC all base their meal plans on the guidelines. If these recommendations are flawed, the repercussions extend to millions of Americans, particularly vulnerable populations who rely on these programs.
Moreover, the guidelines shape public perceptions of healthy eating. The vilification of saturated fat has led many to avoid nutrient-dense foods like dairy, meat, and eggs, potentially missing out on essential vitamins and minerals. Simultaneously, the promotion of low-fat and high-carbohydrate diets has normalized the consumption of processed foods, contributing to the obesity epidemic.
Teicholz’s arguments align with a growing movement advocating for personalized nutrition. Critics of the one-size-fits-all approach of the guidelines argue that individual responses to dietary components can vary widely based on genetics, microbiome composition, and other factors. A more nuanced approach to nutrition could better address the diverse needs of the population.
Teicholz advocates several changes in the way dietary recommendations are developed.
She would like greater reliance on randomized controlled trials and systematic reviews, more transparency about conflicts of interest, greater consideration of dissenting scientific perspectives, and a willingness to reconsider longstanding recommendations when new evidence emerges.
She also questions whether a single dietary prescription is appropriate for everyone.
People differ in metabolic health, genetics, activity, glucose regulation, and responses to particular foods.
Future nutrition policy may need to accommodate more than one path to a healthy diet.
Nina Teicholz’s critique of the U.S. Dietary Guidelines highlights significant shortcomings in the current approach to nutrition policy. Her arguments challenge decades of conventional wisdom, emphasizing the need for a more evidence-based, transparent, and inclusive process. While her conclusions are not without controversy, they have ignited an important debate about the role of science, politics, and industry in shaping public health recommendations.
Are our dietary recommendations based on evidence strong enough to justify the confidence with which they have been presented?
Teicholz believes the answer has too often been no.
Her conclusions may remain disputed, but I find her quite convincing. Her book, articles and interviews were persuasive. Decide for yourself if we have been getting bad advice for decades. In my opinion, her book could have been called "The Big Fat Lie."
Whether or not one agrees with all of her conclusions, her work provides a useful starting point for understanding why the conventional advice to eat less fat and more carbohydrates has increasingly been questioned.
Nina Teicholz's newsletter on nutrition science and policy.