Reviewed by Dr. Eric Westman, MD, MHS: June 2025
For decades, a pervasive fear has gripped our dietary consciousness: the fear of fat and cholesterol. We have been diligently trimming the fat off our steaks, opting for low-fat everything, and viewing a pat of butter as a direct assault on our arteries. This dogma, often reinforced during routine doctor’s visits, has painted a simple picture of good versus evil in our bodies. But what if this narrative, this foundational “cholesterol and fat myth,” is not the whole truth? What if the dietary villains we have been taught to fear are merely scapegoats for more sinister culprits lurking in our modern diet?
This article will delve into the complex and often misunderstood world of dietary fats and cholesterol. We will explore the historical context of how these essential nutrients were vilified, examine the science that is debunking long-held beliefs, and reveal what your doctor might not be telling you about what truly drives heart disease. Prepare to question the dietary advice you have taken as gospel and to discover a new perspective on what it means to eat for a healthy heart.
The Genesis of a Dietary Dogma: How Fat and Cholesterol Took the Blame
The story of how fat and cholesterol became public health enemies number one can be traced back to the mid-20th century and the influential, yet deeply flawed, research of a scientist named Ancel Keys. His “Seven Countries Study” appeared to draw a straight line between the consumption of saturated fat, elevated cholesterol levels, and a higher risk of heart disease. This “diet-heart hypothesis” quickly gained traction, heavily influencing the dietary guidelines of governments and health organizations worldwide.
The food industry, in turn, capitalized on this burgeoning fear. Supermarket shelves became inundated with “low-fat” and “fat-free” products, often laden with sugar and refined carbohydrates to compensate for the loss of flavor and texture from the removal of fat. The message was clear and simple: to save your heart, you must banish fat and cholesterol from your plate. This oversimplified message, however, set the stage for a public health crisis of a different kind, as we will see.
Unpacking Cholesterol: More Than Just “Good” and “Bad”
One of the most significant oversimplifications in the cholesterol narrative is the reduction of this vital substance to a simple dichotomy of “good” (HDL) and “bad” (LDL). The truth is far more nuanced. Cholesterol is not inherently evil; in fact, it is a waxy, fat-like substance that is essential for life. It is a crucial building block for our cell membranes, a precursor to vital hormones like estrogen and testosterone, and necessary for the synthesis of vitamin D. Our liver produces the vast majority of the cholesterol our bodies need, and for most people, the cholesterol consumed in food has a surprisingly small impact on the levels of cholesterol in their blood.
The distinction between HDL (high-density lipoprotein) and LDL (low-density lipoprotein) is not about the cholesterol itself, but about the lipoprotein particles that transport it through the bloodstream. HDL is often dubbed “good” because it carries cholesterol away from the arteries and back to the liver for processing. LDL, on the other hand, transports cholesterol to the cells. The traditional view holds that high levels of LDL lead to the buildup of plaque in the arteries (atherosclerosis).
However, what your doctor might not be telling you is that the standard lipid panel, which measures total LDL cholesterol (LDL-C), can be a poor predictor of heart disease risk. More advanced testing reveals that the size and number of LDL particles (LDL-P) are far more critical. Small, dense LDL particles are more strongly associated with cardiovascular disease compared to LDL particles that are “large and fluffy.” A person can have normal or even low LDL-C levels, but a high number of these small, dense LDL particles, putting them at a significantly higher risk.
The Saturated Fat Saga: A Story of Misplaced Blame
Saturated fat has long been considered the primary dietary driver of high LDL cholesterol and, by extension, heart disease. We have been advised to limit our intake of red meat, butter, and full-fat dairy products. However, a growing body of scientific evidence is challenging this long-held belief. Numerous large-scale studies and meta-analyses have failed to find a consistent, strong link between the consumption of dietary saturated fat and an increased risk of heart disease.
The context of the overall diet is paramount. Saturated fat consumed as part of a diet high in sugar and refined carbohydrates is likely to have a different effect than when it is part of a whole-foods-based, low-carbohydrate diet. It is becoming increasingly clear that the blanket demonization of saturated fat has been a misguided and potentially harmful public health strategy.
The Real Dietary Demons: Sugar, Refined Carbohydrates, and Industrial Oils
If saturated fat and dietary cholesterol are not the primary culprits, what is? The scientific evidence is pointing a far more convincing finger at a trio of modern dietary staples: sugar, refined carbohydrates, and industrial seed oils. When we consume an excess of sugar and refined grains (like white bread, pasta, and pastries), our bodies experience a surge in insulin. Over time, this can lead to insulin resistance, a condition at the heart of many chronic diseases, most notably type 2 diabetes. This state of high insulin and insulin resistance promotes inflammation and signals the liver to produce more of the small, dense, and dangerous LDL particles. Furthermore, a high intake of sugar can lead to the formation of advanced glycation end products (AGEs), which can damage proteins in the body and contribute to inflammation and oxidative stress, key drivers of atherosclerosis.
Taking Charge of Your Health: A New Path Forward
The “cholesterol and fat myth” has persisted for decades, in part due to institutional inertia, the influence of the food and pharmaceutical industries, and the slow pace at which medical education adapts to new scientific findings. The focus on lowering cholesterol with medication (such as statins) has been a cornerstone of cardiovascular disease prevention, yet it fails to address the root cause. Empowering yourself with this knowledge is the first step toward true metabolic health. It is time to shift our focus from the outdated and simplistic fear of fat and cholesterol to a more nuanced understanding of how our bodies work. This means having more informed conversations with your doctor, questioning the standard dietary advice, and perhaps even requesting more advanced cholesterol testing to understand your true risk profile.
A heart-healthy diet is not about fat-free products and bland meals. It is about embracing a whole-foods-based approach. This includes:
- Healthy Fats: Enjoy a variety of natural fats from sources like avocados, coconut, beef, butter, nuts, seeds, olive oil, and fatty fish.
- Quality Protein: Include well-sourced meat, poultry, fish, and eggs in your diet.
- Vegetables as Tolerated: Include non-starchy vegetables in your diet to add variety while keeping carbs low, but avoid any that cause adverse effects for you.
- Limiting the Culprits: Substantially reduce or eliminate your intake of added sugars, refined carbohydrates, and processed foods containing industrial seed oils.
The tide is turning on the myths about dietary fat, cholesterol, and cardiovascular disease The narrative that has dominated our understanding of heart health for over half a century is crumbling under the weight of modern scientific inquiry. By understanding the real drivers of heart disease—inflammation, insulin resistance, and the overconsumption of sugar and processed foods—we can finally absolve fat and cholesterol of their undeserved bad reputation and embrace a diet that truly nourishes and protects our bodies for the long term.
Sources
- The Flaws of the Seven Countries Study: Teicholz, N. (2014). The Big Fat Surprise: Why Butter, Meat and Cheese Belong in a Healthy Diet. Simon & Schuster. This book provides a deep-dive investigation into the history of the diet-heart hypothesis and a thorough critique of Ancel Keys’ research and its influence on public policy. A summary of these points can also be found in numerous health articles and scientific reviews discussing the history of dietary guidelines.
- Essential Roles of Cholesterol: Harvard Health Publishing. (2019). “How it’s made: Cholesterol production in your body.” This article, along with standard medical and biology textbooks, outlines the critical functions of cholesterol in building cell membranes, synthesizing hormones like estrogen and testosterone, and producing vitamin D.
- Dietary Cholesterol’s Limited Impact: Soliman, G. A. (2018). Dietary Cholesterol and the Lack of Evidence in Cardiovascular Disease. Nutrients, 10(6), 780. This review article analyzes the scientific literature and concludes that evidence does not support a link between dietary cholesterol and cardiovascular disease in healthy individuals. The 2015-2020 and 2020-2025 Dietary Guidelines for Americans also removed the specific daily limit for dietary cholesterol, citing a lack of evidence for its role in increasing blood cholesterol.
- LDL Particle Size as a Risk Factor: Cromwell, W. C., & Otvos, J. D. (2004). Low-density lipoprotein particle number and risk for cardiovascular disease. Current Atherosclerosis Reports, 6(5), 381-387. This is one of many studies and review articles concluding that LDL particle number (LDL-P) is a more accurate and potent indicator of atherosclerotic cardiovascular disease risk than the standard measurement of LDL cholesterol (LDL-C).
- Re-evaluating Saturated Fat: de Souza, R. J., et al. (2015). Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies. The BMJ, 351, h3978. This comprehensive meta-analysis found no significant association between the intake of saturated fat and the risk of heart disease, stroke, or type 2 diabetes.
- Sugar and Refined Carbs as Drivers of Heart Disease: DiNicolantonio, J. J., Lucan, S.C. & O’Keefe, J. H. (2016). The Evidence for Saturated Fat and for Sugar Related to Coronary Heart Disease. Progress in Cardiovascular Diseases, 58(5), 464-472. This paper details the mechanisms by which high consumption of refined carbohydrates and sugar promotes dyslipidemia, inflammation, insulin resistance, and ultimately, a higher risk of coronary heart disease.
Author Bio
Eric Westman, MD, MHS, is an Associate Professor of Medicine at Duke University, the Medical Director of Adapt Your Life Academy and the founder of the Duke Keto Medicine Clinic in Durham, North Carolina. He is board-certified in Internal Medicine and Obesity Medicine and has a master’s degree in clinical research. As a past President of the Obesity Medicine Association and a Fellow of the Obesity Society. Dr. Westman was named “Bariatrician of the Year” for his work in advancing the field of obesity medicine. He is a best-selling author of several books relating to ketogenic diets as well as co-author on over 100 peer-reviewed publications related to ketogenic diets, type 2 diabetes, obesity, smoking cessation, and more. He is an internationally recognized expert on the therapeutic use of dietary carbohydrate restriction and has helped thousands of people in his clinic and far beyond, by way of his famous “Page 4” food list.
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