Food Truths from the world's top nutrition scientist | Walter Willett, PhD

The Proof with Simon Hill

Simon Hill

Nutrition, Health & Fitness, Self-improvement, Education

4.9 • 2.9K Ratings

🗓️ 1 December 2025

⏱️ 125 minutes

🔗️ Recording | iTunes | RSS

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Summary

Dr Walter Willett has spent more than fifty years at the forefront of nutrition research, leading landmark studies that have shaped how we think about fat, carbohydrates, protein and chronic disease. In this episode, he joins me to untangle decades of confusion around saturated fat, seed oils, dairy, eggs, plant protein and more, and to explain what a truly healthy dietary pattern looks like when you consider both human health and planetary health. We explore how evidence from long term cohorts, clinical trials and global dietary patterns converges on a common theme, and what the Planetary Health Diet means in practical terms for you and your family. What We Cover How nutrition science has evolved and why the big picture is now clearer. Why the source of fat and carbohydrate matters more than the amount. The truth about seed oils, saturated fats, and dairy. Protein quality, plant to animal ratios, and what matters most for longevity. How diet affects cognitive ageing and dementia risk. The planetary health diet and how to eat for both people and planet. This is a nuanced, evidence based conversation with one of the most influential nutrition scientists of our time. I hope it helps you feel less confused and more empowered in the choices you make every day. The Fat Misconception of the 1970s (00:01:35) Media, Internet & Public Misinformation (00:05:36) Current Blind Spots & Future Predictions (00:09:55) Dietary Changes & Public Health Impact (00:13:47) Why the Mediterranean Diet Still Leads the Pack (00:18:02 How Nutrition Research Really Works (00:23:33) Fats, Oils, and the Myths That Won’t Die (00:32:57) Dairy: Health vs. Environmental Costs (00:45:35) Protein Intake & Healthy Aging (00:59:57) Fiber's Role in Health (01:19:59) Can Diet Protect Our Brain? (01:29:43) Food Choices and the Future of the Planet (01:40:48) This episode is brought to you by: 38TERA Consider 38TERA's DMN prebiotic supplement a daily multivitamin for your gut. Formulated by yours truly and gastroenterologist Dr Will Bulsiewicz. Use code THEPROOF for a discount at checkout. Function Health Take charge of your health with advanced blood testing and personalised insights. Function Health offers a practical way to track key health markers such as cholesterol, blood sugar, and more. Learn more and join at functionhealth.com/simonhill for a $25 credit toward your membership. Only available to those living in the United States. LMNT Stay hydrated with LMNT. Get a free Sample Pack of LMNT’s most popular drink mix flavours with any purchase at DrinkLMNT.com/SIMON Find your favourite LMNT flavour, or share with a friend. And if you don’t like it? Full refund, no questions asked. IM8 With 92 nutrients, including Vitamin B12, Iodine, Selenium and Vitamin D, in highly absorbable forms, IM8 Daily Essentials is the perfect all-in-one daily multi-vitamin to ensure you meet your daily micronutrient needs. IM8 is offering an exclusive 10% off your first order with a free welcome kit when you enter the promo code SIMON at checkout on im8health.com Eight Sleep Upgrade your sleep with the Pod 5 Ultra by Eight Sleep. Clinically validated to deliver up to 1 extra hour of quality sleep per night through temperature control and biometric tracking. Use code THEPROOF for $400 off at eightsleep.com/theproof. Try it risk-free for 30 days, with worldwide shipping. SKIMS Upgrade your underwear drawer with SKIMS Mens. Soft, stretchy and built to stay in shape, they provide comfort and freedom of movement for training or everyday wear. Shop SKIMS Mens at SKIMS.com. Let them know we sent you! After you order, select "podcast" in the survey and choose The Proof from the dropdown. And if you’re looking for the perfect gifts this season - the SKIMS Holiday Shop is now open at SKIMS.com.

Transcript

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0:00.0	Alrighty friends, today I'm welcoming back someone who has shaped modern nutrition and public health more than almost anyone.
0:08.0	Dr. Walter Willard, physician and the world's most cited nutrition scientist.
0:14.0	It's been a few years since he was last on the proof and with the nutrition landscape only becoming more and more confusing, this felt like
0:22.8	the perfect moment for a deeper, more reflective conversation. Across 50 plus years at Harvard,
0:29.8	Dr. Willett has followed hundreds of thousands of people, producing some of the most influential
0:35.4	data that we have on diet and long-term health.
0:39.3	In this conversation, we explore how his thinking has evolved, what he's changed his mind on,
0:44.3	how low-fat messaging fueled a wave of ultra-processed food consumption,
0:49.3	and why polyunsaturated fats, especially omega-3s, remain essential. We also break down how to think
0:55.9	about dairy fat in 2025, what the evidence really shows us about the best protein sources
1:01.6	for long-term health, and what decades of cohort data reveal about eating for long-term brain
1:07.8	health and protecting cognition as we age.
1:10.9	And in case you're wondering, yes, I made sure to ask Dr. Willett about his own personal food
1:16.8	choices, how he eats today, how this approach has shifted over time,
1:21.3	and why he's concerned about dietary advice from major maha figures like RFK Jr. Plenty of juicy stuff in this one. Please enjoy.
1:35.4	Walter, you've been at the center of nutrition science for decades now. Looking back over that time,
1:48.5	what do you think the field has mostly got right? And what would you say the field has got wrong? Well, probably the field was most off target. When I started
1:57.0	working in this area, this was back in the 1970s. And at that time, the main advice,
2:03.6	the main belief was that all fat is bad and everybody should reduce all fats and oils as much
2:09.3	as possible. That was the center of the food guide pyramid and dietary advice when the pyramid
2:16.0	first came out here in this country in 1993.
2:19.0	And, of course, if you're not going to eat fat, it means loading up on carbohydrates.
	...

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