Is Your Cooking Oil Making You Sick?

For decades, the blame for metabolic disease has swung between sugar and saturated fat. But a provocative new hypothesis is shifting the focus to a third, often overlooked culprit: refined seed oils.

In a 2025 paper published in Frontiers in Nutrition, Dr. Catherine Shanahan introduces the Energy Model of Insulin Resistance, a bold and integrative framework that connects the rise of insulin resistance and metabolic diseases—not to sugar or saturated fats, but to refined, bleached, and deodorized (RBD) seed oils like soybean, corn, and canola oil (Shanahan, 2025). These oils now account for nearly one-third of the average American’s caloric intake.

🔍 A New Lens on Insulin Resistance

Shanahan’s model challenges conventional thinking. Instead of viewing insulin resistance as a primary defect in insulin signaling, she suggests it arises from an increased cellular demand for glucose—a compensatory shift driven by oxidative stress and mitochondrial dysfunction.

Here’s how it unfolds:

1. Seed Oils Increase Oxidative Stress

   Polyunsaturated fats (PUFAs) in seed oils are highly prone to oxidation, especially when stripped of antioxidants during industrial processing. The lipid oxidation products (LOPs) that result can damage cells and mitochondria.

   
   

2. Mitochondria Get Overwhelmed

   As oxidized PUFA-rich fat is burned for energy, mitochondrial antioxidant defenses collapse. This leads to dysfunction and triggers a survival response: the Warburg Effect, where cells favor glucose over fat—even in the presence of oxygen.

   
   

3. Glucose Demand Soars

   With many cells switching to glucose as a safer energy source, blood sugar is rapidly consumed, especially between meals. This may trigger subclinical hypoglycemia, activating stress hormones like cortisol and adrenaline to raise blood sugar—while simultaneously dulling insulin's signal.

   
   

4. Insulin and Stress Hormones

   CollideElevated insulin and counter-regulatory hormones coexist, producing the hallmark of insulin resistance: high blood sugar despite high insulin. Over time, the brain may even "reset" to defend higher glucose levels, deepening the dysfunction.

🧬 What Makes This Model Different?

The Energy Model reframes metabolic disease as a bioenergetic adaptation, not just a breakdown. It aligns with emerging science on mitochondrial health, oxidative stress, and immune-metabolic interactions. Crucially, it offers an explanation for puzzling observations:

• Why fit athletes and normal-weight individuals can still become insulin resistant.

• Why saturated fat isn't consistently linked to heart disease in well-controlled studies.

• Why modern adipose tissue has over 20% linoleic acid today, up from just 5–10% in the 1950s.

• Why many people feel “hypoglycemic” even when their blood sugar is normal.

🛑 Rethinking Dietary Dogma

Despite decades of advice to replace animal fats with vegetable oils, Shanahan argues that RBD seed oils may be the Trojan Horse in our food system. Initially developed for industrial use, these oils were never tested for long-term safety in humans before their mass adoption. Yet they’ve become the backbone of processed foods and institutional meal planning.

Her message is clear: we’ve underestimated the impact of these oils on our metabolic machinery.

📚 The Bottom Line

Dr. Shanahan’s Energy Model of Insulin Resistance is a powerful new narrative that connects dietary changes, oxidative stress, mitochondrial damage, and chronic disease into a single, testable framework. It calls for a re-examination of dietary guidelines and a deeper investigation into the bioenergetic consequences of what we eat.

It’s a reminder that not all calories—or fats—are metabolically equal.

Reference:

Shanahan C. (2025). The energy model of insulin resistance: A unifying theory linking seed oils to metabolic disease and cancer. Frontiers in Nutrition, 12:1532961. https://doi.org/10.3389/fnut.2025.1532961