#291 - Why No Diet Wins (and What 40 Years of Nutrition Research Actually Shows) | Christopher Gardner, PhD, & Mike Haney
Fri Jan 30 2026
In this episode of A Whole New Level, Christopher Gardner, PhD, joins Mike to discuss his decades in nutrition research, the challenges of conducting randomized controlled trials (RCTs) on diet, and how to communicate complex science to the public. Gardner has led some of the most rigorous research ever comparing dietary approaches in real-world conditions, so his insights about what works (cutting processed food and sugar) and what doesn’t (obsessing about macronutrients) are worth a listen.
Sign Up to Get Your Free Ultimate Guide to Glucose: https://levels.link/wnl
In this episode, we cover:
What a nutritional interventionist is – someone who studies people who are asked to change their diet, tracking them and taking samples to see what might have changed.How to square widely-accepted lessons about nutrition (i.e., junk food=bad) with the high degree of individuality in diets that work.The concept of "equipoise" in study design, which means making sure both diets being compared are well-represented versions of that diet (e.g., a "kick butt diet A and a crappy diet B" is avoided).The dilemma of communicating single-study results to the public and the role of the Netflix documentary on Gardner’s famous twin study in making science engaging.Dr. Gardner's experience on the Dietary Guidelines Advisory Committee and the methodology used to reach conclusions.The focus on ultra-processed foods and the need to message the consensus points of eating more whole foods and vegetables, and avoiding added sugar and refined grains.The learnings from the DIETFITS study, which compared low-carb and low-fat diets among 600 people for a year, and why there was more variation among people within a diet than between the two diets.
🎙 What Dr. Christopher Gardner & Mike Haney discuss:
[00:33] Nutritional Interventionist Role
[02:17] Shortcomings of Nutrition RCTs
[03:59] Garlic Study Example
[16:48] Concept of Equipoise in Study Design
[21:54] Value of Communicating Single Study Results
[28:02] Industry Funding and Transparency
[33:11] Dietary Guidelines Advisory Committee Methodology
[38:48] Ultra-Processed Foods and the Evidence
[48:27] Simplicity vs. Complexity in Nutrition
[50:24] Consensus on Foundational Diet Components
Levels helps you see how food affects your health, empowering you with the tools needed to achieve health goals and improve healthspan. Levels Members gain access to the Levels app and continuous glucose monitors (CGMs), providing real-time feedback on how diet and lifestyle choices impact your metabolic health.
Look for new shows every month on A Whole New Level, where we have in-depth conversations with thought leaders about metabolic health.
🔗 Helpful links
Watch the conversation: https://youtu.be/ZQ0G_jfwKoM
Find us on YouTube: https://youtube.com/levelshealth?sub_confirmation=1
📲 Connect
Connect with Christopher Gardner, PhD, on Instagram: https://www.instagram.com/cgardnerphd/?hl=en
More
In this episode of A Whole New Level, Christopher Gardner, PhD, joins Mike to discuss his decades in nutrition research, the challenges of conducting randomized controlled trials (RCTs) on diet, and how to communicate complex science to the public. Gardner has led some of the most rigorous research ever comparing dietary approaches in real-world conditions, so his insights about what works (cutting processed food and sugar) and what doesn’t (obsessing about macronutrients) are worth a listen. Sign Up to Get Your Free Ultimate Guide to Glucose: https://levels.link/wnl In this episode, we cover: What a nutritional interventionist is – someone who studies people who are asked to change their diet, tracking them and taking samples to see what might have changed.How to square widely-accepted lessons about nutrition (i.e., junk food=bad) with the high degree of individuality in diets that work.The concept of "equipoise" in study design, which means making sure both diets being compared are well-represented versions of that diet (e.g., a "kick butt diet A and a crappy diet B" is avoided).The dilemma of communicating single-study results to the public and the role of the Netflix documentary on Gardner’s famous twin study in making science engaging.Dr. Gardner's experience on the Dietary Guidelines Advisory Committee and the methodology used to reach conclusions.The focus on ultra-processed foods and the need to message the consensus points of eating more whole foods and vegetables, and avoiding added sugar and refined grains.The learnings from the DIETFITS study, which compared low-carb and low-fat diets among 600 people for a year, and why there was more variation among people within a diet than between the two diets. 🎙 What Dr. Christopher Gardner & Mike Haney discuss: [00:33] Nutritional Interventionist Role [02:17] Shortcomings of Nutrition RCTs [03:59] Garlic Study Example [16:48] Concept of Equipoise in Study Design [21:54] Value of Communicating Single Study Results [28:02] Industry Funding and Transparency [33:11] Dietary Guidelines Advisory Committee Methodology [38:48] Ultra-Processed Foods and the Evidence [48:27] Simplicity vs. Complexity in Nutrition [50:24] Consensus on Foundational Diet Components Levels helps you see how food affects your health, empowering you with the tools needed to achieve health goals and improve healthspan. Levels Members gain access to the Levels app and continuous glucose monitors (CGMs), providing real-time feedback on how diet and lifestyle choices impact your metabolic health. Look for new shows every month on A Whole New Level, where we have in-depth conversations with thought leaders about metabolic health. 🔗 Helpful links Watch the conversation: https://youtu.be/ZQ0G_jfwKoM Find us on YouTube: https://youtube.com/levelshealth?sub_confirmation=1 📲 Connect Connect with Christopher Gardner, PhD, on Instagram: https://www.instagram.com/cgardnerphd/?hl=en