What truly defines a healthy diet, and why does nuance get lost in online nutrition debates? In this episode of The Proof, I’m joined once again by Dr David Katz, physician, nutrition researcher, and internationally recognised leader in preventive medicine. We unpack the science of diet quality, the role of balance, the impact of ultra-processed foods, and why both human and planetary health must be part of the same conversation.
David shares lessons from decades of research and clinical practice, including his reflections on the ongoing “diet wars” and how stories can overshadow science on social media. Together, we explore what all healthy diets have in common and how shifting both food demand and food supply is key to solving the chronic disease crisis.
What we cover:
- Why diet quality is the leading predictor of health and longevity
- How to define a truly balanced plate
- Why beef is uniquely problematic for human and planetary health
- The rise of keto and carnivore diets, anecdotes versus long-term evidence
- Ultra-processed foods, what they are and why they drive overconsumption
- Supplements, when they help, when they don’t, and what David takes himself
- The bigger picture, food environment, policy, and planetary health
A powerful conversation that cuts through ideology and helps you make sense of nutrition science in the real world.
You can connect with Dr David Katz on LinkedIn, Facebook, and X (Twitter). To learn more about his work, visit davidkatzmd.com, explore Diet ID, and discover the True Health Initiative.
- The Critical Role of Diet in Chronic Disease and Longevity (00:00:00)
- What Does a High-Quality Diet Actually Mean? (00:05:03)
- Why Balance Is the Essence of Diet Quality (00:12:07)
- What Does a Balanced Diet Look Like in Practice? (00:20:30)
- Why Should We Eat Less Beef? (00:23:44)
- Plant-Based vs Omnivore Diets: Which Is Healthier? (00:30:25)
- Are Keto and Carnivore Diets Healthy Long-Term? (00:38:49)
- How Can We Fight Nutrition Misinformation? (00:45:56)
- How Ultra-Processed Foods Hijack Appetite and Drive Overeating (01:00:12)
- How Do We Tell Good vs Bad Ultra-Processed Foods? (01:10:32)
- Can Reformulated Ultra-Processed Foods Improve Public Health? (01:19:04)
- How Measuring Diet Quality Could Transform Public Health (01:26:50)
- How Diet ID Measures and Improves Diet Quality (01:31:15)
- Do Supplements Work and Which Ones Are Worth Taking? (01:43:11)
- Lessons From 40 Years in Medicine and Public Health (01:52:14)
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More about David L. Katz
David L. Katz, MD, MPH, ACPM, FACP, FACLM is a specialist in Internal Medicine, Preventive Medicine/Public Health, and Lifestyle Medicine, with particular expertise in nutrition.
He earned his BA at Dartmouth College (1984); his MD at the Albert Einstein College of Medicine (1988); and his MPH from the Yale University School of Public Health (1993). He completed sequential residency training and board certification in Internal Medicine (1991) and Preventive Medicine/Public Health (1993).
Katz is the founder and former director of Yale University’s Yale-Griffin Prevention Research Center (1998-2019), where he secured and managed roughly $40M in research funding. He is Past President of the American College of Lifestyle Medicine; Founder of the non-profit True Health Initiative; and Founder and CEO of Diet ID, Inc. He has served as Chief Medical Officer for Tangelo, an award-winning food-as-medicine company. He serves as a senior science advisor to Blue Zones and Blue Zones Health.
Katz held faculty positions at the Yale schools of Medicine, Public Health, and Nursing. He cared for patients in the context of primary care Internal Medicine and an innovative model of Integrative Medicine for roughly 30 years, receiving awards for both clinical care and bedside teaching. He served as a residency director in both Preventive Medicine and evidence-based Integrative Medicine. He was the lead architect of the nation’s first fully accredited, combined training program in Internal Medicine and Preventive Medicine. Katz was the inaugural editor-in-chief of the peer-reviewed journal, Childhood Obesity, serving in that role for 5 years.
He is a Fellow of the American College of Preventive Medicine; the American College of Physicians; the American College of Lifestyle Medicine; and Morse College, Yale University.
The recipient of numerous awards for teaching, writing, and contributions to public health, Katz was a 2019 James Beard Foundation Award nominee in health journalism, has been a widely supported nominee for the position of U.S. Surgeon General, and has received three honorary doctorates. He is a 2023 recipient of a Lifetime Achievement Award from the Doctors’ World Gala, and the 2024 recipient of the President’s Award from the American College of Lifestyle Medicine. He was inducted into Sigma Xi, the scientific research honor society, in 2025.
Katz has an extensive media portfolio, having served as a nutrition columnist for O, the Oprah Magazine; an on-air contributor for ABC News/Good Morning America; and with appearances on most major news programs and contributions to most major magazines and leading newspapers, including OpEds in the New York Times and Wall Street Journal. He is one of the original 150 “Influencers” selected by LinkedIN, and has a social media following of nearly one million.
He holds multiple U.S. patents; has roughly 250 peer-reviewed publications; has published many hundreds of on-line and newspaper columns; and has authored/co-authored 19 books to date including multiple editions of leading textbooks in nutrition, preventive medicine, and epidemiology. His most recent book for a general audience, How to Eat, co-authored with Mark Bittman, was a 2021 IACP Awards finalist.
His career-long focus has been the translation of science into action for the addition of years to life, and life to years, and on the confluence of human and planetary health.
On the COVID pandemic, he advocated consistently for a policy of total harm minimization (https://www.truehealthinitiative.org/covid/) by means of risk-stratified interdiction efforts- and for addressing the “prior pandemic” of cardiometabolic disease that contributes so much to acute risk. These views were extensively covered in the New York Times. His commentary on lessons in the pandemic in the American Journal of Health Promotion was recognized among the journal’s “Best Papers of 2024.”
Katz has presented at conferences in all 50 U.S. states and in multiple countries on six continents. Represented by the Harry Walker Agency, he has been recognized by peers as the “poet laureate of health promotion.”
He and his wife, Catherine, live in Connecticut. They have five grown children.
