The Big Fat Surprise

1. The diet-heart hypothesis: A flawed foundation of modern nutrition

Keys's unwavering belief in his own hypothesis, even in its formative stages and even in the face of conflicting evidence, however, suggests he was willing to stray from these scientific principles to defend it.

Ancel Keys' influence: In the 1950s, Ancel Keys proposed the diet-heart hypothesis, suggesting that dietary fat, especially saturated fat, caused heart disease. This idea quickly gained traction despite limited evidence.

Flawed methodology: Keys' Seven Countries Study, often cited as proof of the hypothesis, had significant methodological issues:

• Selective country inclusion
• Small sample sizes
• Data collection during Lent (skewing results)
• Ignoring contradictory findings within countries

Suppression of opposing views: The nutrition community, led by Keys and his allies, systematically marginalized researchers who questioned the diet-heart hypothesis, creating an echo chamber that reinforced their beliefs.

2. Saturated fat: Wrongly vilified and potentially beneficial

So it seems fair to say that at the height of the meat-and-butter-gorging eighteenth and nineteenth centuries, heart disease did not rage as it did by the 1930s.

Historical perspective: Contrary to popular belief, Americans in the 18th and 19th centuries consumed significantly more red meat and saturated fat than today, without the epidemic of heart disease we now face.

Nutritional benefits: Saturated fats from animal sources provide:

• Essential vitamins (B12, B6, A, D, K, E)
• Minerals (iron, zinc, selenium)
• High-quality protein

Cholesterol effects: While saturated fat can raise LDL cholesterol, it also:

• Increases HDL (good) cholesterol
• Improves the LDL particle size profile (larger, less harmful particles)
• Has no clear link to increased heart disease risk in modern studies

3. The Mediterranean Diet: More myth than miracle

Keys had developed a sizable following among his nutrition colleagues, yet at least one scientist in his audience, Jacob Yerushalmy, was not impressed.

Origin and promotion: The Mediterranean Diet concept, popularized by Ancel Keys and later researchers, was based on limited and potentially flawed data from post-World War II Crete.

Questionable evidence:

• Small sample sizes (as few as 33 men on Crete)
• Data collection during Lent, skewing results
• Ignoring contradictory findings
• Retroactive construction of an "ideal" diet that didn't reflect actual eating patterns

Industry influence: The promotion of the Mediterranean Diet was heavily supported by the olive oil industry, potentially biasing research and public perception.

4. Trans fats: From solution to health hazard

Ironically—or perhaps tellingly—the heart disease "epidemic" began after a period of exceptionally reduced meat eating.

Rise of hydrogenated oils: Trans fats, created through hydrogenation of vegetable oils, became widespread in the food supply as a replacement for animal fats deemed unhealthy.

Health consequences:

• Increased LDL cholesterol
• Decreased HDL cholesterol
• Higher risk of heart disease
• Potential links to other chronic diseases

Industry suppression: Food companies and industry groups actively suppressed research highlighting the dangers of trans fats for decades, delaying public awareness and regulatory action.

5. Vegetable oils: Unintended consequences of a "heart-healthy" alternative

From the earliest clinical trials in the 1940s, in which diets high in polyunsaturated fats were found to raise mortality from cancer, to these more recent "discoveries" that they contain highly toxic oxidation products, polyunsaturated oils have been problematic for health.

Oxidation concerns: Polyunsaturated vegetable oils, when heated, produce harmful compounds:

• Aldehydes (including formaldehyde)
• Free radicals
• Oxidized LDL cholesterol

Omega-6 imbalance: The dramatic increase in vegetable oil consumption has led to an unhealthy ratio of omega-6 to omega-3 fatty acids in the modern diet, potentially contributing to chronic inflammation.

Limited research: Despite their widespread use and promotion, the long-term health effects of vegetable oils have not been adequately studied, particularly regarding their potential role in cancer and other chronic diseases.

6. Low-fat diets: Failure to deliver on health promises

The Women's Health Initiative (WHI) was the "Rolls Royce of studies," said Thun, and therefore should be the "final word."

Large-scale failure: The Women's Health Initiative, involving nearly 49,000 women over a decade, found no significant benefits of a low-fat diet in preventing heart disease, cancer, or weight gain.

Unintended consequences:

• Increased consumption of refined carbohydrates and sugars
• Potential nutrient deficiencies, especially in fat-soluble vitamins
• Possible contribution to the obesity and diabetes epidemics

Persistence of flawed advice: Despite mounting evidence of their ineffectiveness, low-fat diets continue to be recommended by many health authorities and organizations.

7. Carbohydrates: The real culprit in chronic diseases

Cleave had seen the same phenomenon in so many remote areas to which he traveled in the early 1900s that he called all chronic illnesses the "saccharine diseases," because so many of these ailments arrived in concert with the introduction of refined carbohydrates—principally sugar and white flour.

Historical observations: Researchers like Otto Schaefer and Thomas Cleave documented the emergence of chronic diseases in isolated populations following the introduction of refined carbohydrates.

Metabolic effects:

• Insulin spikes and chronic elevation
• Increased fat storage
• Inflammation
• Disrupted hunger and satiety signals

Modern research: Recent studies have increasingly implicated refined carbohydrates and sugars in the development of obesity, diabetes, heart disease, and other chronic conditions.

8. The Atkins Diet: Vindication through scientific scrutiny

In trial after trial and by virtually every indicator that they could measure, the high-fat diet was shown to lower the risk for heart disease and diabetes compared to the one low in fat and saturated fat that the AHA had proposed for Americans for so long.

Initial skepticism: The Atkins Diet, promoting high fat and low carbohydrate intake, was long dismissed by the nutrition establishment as dangerous and ineffective.

Research findings: Rigorous clinical trials in the 2000s demonstrated numerous benefits of low-carb, high-fat diets:

• Greater weight loss
• Improved HDL cholesterol
• Lower triglycerides
• Better blood sugar control
• Reduced inflammation markers

Paradigm shift: The accumulating evidence supporting low-carb, high-fat diets has challenged long-held beliefs about nutrition and health, though resistance from the establishment remains.

9. Cholesterol: Rethinking its role in heart disease

Krauss found that when people eat a diet high in saturated fat, they tend to have mostly large, fluffy LDL-particles that are not associated with a high risk of heart disease.

Evolving understanding: Research by Ronald Krauss and others has revealed that the relationship between cholesterol and heart disease is more complex than previously thought.

Key findings:

• LDL particle size matters more than total LDL cholesterol
• HDL cholesterol is a stronger predictor of heart disease risk
• Saturated fat consumption can improve overall lipid profiles

Implications: These discoveries challenge the basis of many dietary recommendations and suggest that the focus on lowering total cholesterol may have been misguided.

10. Nutrition science: The need for paradigm shift and unbiased research

"Can we get the low-fat proponents to apologize?"

Entrenched beliefs: The nutrition establishment has been slow to acknowledge flaws in the diet-heart hypothesis and other long-held beliefs, despite mounting evidence.

Funding bias: Much nutrition research has been influenced by industry funding and preconceived notions, potentially skewing results and interpretations.

Call for reform:

• Greater emphasis on rigorous, long-term clinical trials
• Reduction of conflicts of interest in research and policy-making
• Openness to alternative hypotheses and paradigm shifts
• Improved science communication to the public and policymakers

Last updated: January 23, 2025