Episode 252: Dr. Cate Shanahan - Are Seed Oils as Bad as Sugar?

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Oct 23, 2025

Dr. Cate Shanahan, a family physician and nutrition consultant, dives deep into the dangers of industrial seed oils. She explains how these oils can contribute to sugar cravings and insulin resistance, invoking biochemical mechanisms like oxidation and mitochondrial stress. The 'Hateful Eight' oils are discussed—corn, canola, and others to avoid. Dr. Shanahan offers practical alternatives, advocating for unrefined oils like olive and coconut. Tune in for insights on how changing your fats can transform your health and well-being!

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ADVICE

Choose Unrefined, Flavorful Oils

Avoid refined, flavorless seed oils and favor unrefined, flavorful oils like extra-virgin olive, sesame, and virgin peanut.
Use fruit-based oils (olive, avocado, coconut) and unrefined nut/seed oils for flavor and nutrition.

INSIGHT

Marketing Shaped Oil Science And Policy

Aggressive marketing and alliances with organizations like the American Heart Association helped normalize refined seed oils in the food supply.
This historical influence explains why many clinicians still regard these oils as healthy.

INSIGHT

Mitochondrial Damage Links To Disease

Oxidized seed oils deplete antioxidants and damage mitochondria, driving inflammation and degenerative disease.
This mitochondrial damage underlies many chronic conditions including metabolic and neurodegenerative diseases.

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Dr. Vera Tarman sits down with Dr. Cate Shanahan, family physician, nutrition consultant, and author of Deep Nutrition and Dark Calories, to discuss her case against industrial seed oils, how they may influence metabolic and mental health, and why she believes they can intensify sugar cravings and insulin resistance. We explore mechanisms she proposes (oxidation, mitochondrial stress), the "Hateful Eight" oils, and practical swaps that listeners can try if they choose to reduce seed oils. This episode presents a viewpoint that's debated in nutrition science; we encourage critical thinking, self-experimentation within a safe plan, and consultation with your care team.

What we cover

Seed oils vs. sugar: Why Dr. Shanahan argues seed oils may drive sugar cravings and insulin resistance.
Oxidation & mitochondria: Her biochemical rationale for how highly unsaturated oils can oxidize and affect cell energy.
The "Hateful Eight": Corn, canola, cottonseed, soybean, sunflower, safflower, rice bran, grapeseed—why she cautions against them.
Historical context: Marketing, refinement, and how these oils entered the food supply.
Mental health & cravings: Proposed links between oxidized fats, energy instability, mood, and appetite signals.
Practical swaps: Unrefined olive, avocado, coconut, butter/ghee; flavor-forward nut/seed oils used unheated; reading labels and cooking at home.
Diet nuance: Why some low-carb or plant-forward eaters thrive when minimizing seed oils; where refined proteins fit.

Key takeaways

If you experiment with reducing industrial seed oils, pair it with whole-food carbs and adequate protein to support energy stability.
Favor unrefined, flavor-forward oils (e.g., extra-virgin olive oil) and avoid reheating/frying oils repeatedly.
Improvements people report first: steadier energy, fewer GI symptoms, fewer cravings—but your mileage may vary.
This topic is scientifically contested; treat it as a hypothesis to test safely, not a moral rule.

About Dr. Cate

Dr. Cate Shanahan is a board-certified Family Physician with over 20 years of clinical experience reversing disease at its root by avoiding the big three toxic ingredients. She has spent decades translating the warnings of toxicologists about the harms of vegetable oils and sharing those insights here on DrCate.com, with patients, podcast hosts, and in her NY Times bestselling books, including The FatBurn Fix, Deep Nutrition, and Food Rules. Her passion is helping people feel their best.

After getting her BS in biology from Rutgers University, she trained in biochemistry and genetics at Cornell University's graduate school before attending Robert Wood Johnson Medical School. She practiced in Hawaii for ten years where she studied ethnobotany and her healthiest patient's culinary habits. She combined all these scientific fields to write Deep Nutrition: Why Your Genes Need Traditional Food. Together with Dr. Tim DiFrancesco and NBA legend Gary Vitti, she created the PRO Nutrition program for the LA Lakers and helped forge a partnership between Whole Foods Market and numerous NBA teams.

Her insights on the role of seed oils in human disease have been incorporated into Paleo, primal, low-carb, and keto practices.

In May of 2018, she began as Director of Metabolic Health at ABC Fine Wine and Spirits, a progressive, family-run company focused on saving money while improving health.

She's also the Medical & Scientific Advisor at CB Supplements, overseeing their premium-grade multi-collagen protein, and for Beliv, a forward-thinking Latin American beverage company.

Follow Dr. Cate:

Website: https://drcate.com/

Dr. Cate's books: https://drcate.com/which-drcate-book-should-i-buy/

Facebook: https://www.facebook.com/DoctorCate/

Instagram: https://www.instagram.com/drcateshanahan

The content of our show is educational only. It does not supplement or supersede your healthcare provider's professional relationship and direction. Always seek the advice of your physician or other qualified mental health providers with any questions you may have regarding a medical condition, substance use disorder, or mental health concern.