Practical limits when matching foods in trials

In this episode, I’m joined by Dr Kevin Hall from the NIH to unpack the science behind ultra-processed foods, energy balance, and the new U.S. Dietary Guidelines.

We explore what controlled feeding studies reveal about why people tend to eat more calories on ultra-processed diets, and whether it’s the foods themselves or the broader environment driving these effects.

What We Cover

• Key takeaways from the new U.S. Dietary Guidelines
• What ultra-processed foods actually mean in research vs policy
• Why people eat more calories without noticing
• The role of energy density and hyper-palatable foods
• Whether ultra-processed foods can be improved rather than eliminated
• Individual variability in response to diet

A fascinating look at the intersection of biology, behaviour, and the modern food system.

You can learn more about Dr Kevin Hall’s work at his website, follow him on X, or connect on LinkedIn. His book, Food Intelligence: The Science of How Food Both Nourishes and Harms Us, co-authored with Julia Belluz, explores the science of metabolism and ultra-processed foods.

• Intro (00:00)
• 2025 Dietary Guidelines First Impressions (01:03)
• Why They Avoided "Ultra-Processed" Language (04:11)
• The UPF Definition Nobody Agrees On (09:59)
• What Actually Makes You Overeat UPFs (19:08)
• Two Food Properties That Hijack Your Calories (27:38)
• What Happens When You Fix Ultra-Processed Food (34:28)
• Why Big Food Won't Fix Its Own Products (45:08)
• How We Went from Famine Fear to Calorie Glut (51:33)
• Why Some People Overeat UPFs and Others Don't (58:12)
• Is Obesity Actually Genetic? (1:01:22)
• Carbs vs. Fat: What the Data Actually Shows (1:06:34)
• Keto vs. Low-Fat: The Metabolic Ward Results (1:17:35)
• A Top Nutrition Scientist's Honest Diet Advice (1:26:22)
• Will Food Labels Actually Change What You Eat? (1:33:11)
• "Am I a Food Industry Shill?" -Kevin Hall (1:41:36)
• Why Kevin Hall Left the NIH for Drug Research (1:44:29)
• The Study He'd Run With Unlimited Funding (1:47:49)

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.

38Tera ships to the United States, Australia, and New Zealand.

Mill

Mill is an odourless, fully automated food recycler that turns kitchen scraps into clean, dry grounds overnight with no smells or mess. Get $75 off and try it risk-free for 90 days at mill.com using code THEPROOF.

Mill ships within the United States.

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.

IM8 ships to 27 countries including the U.S., Canada, the U.K., Australia, and many regions across Europe, Asia, and South America.

Momentous

My go-to supplement brand for protein and creatine is Momentous. Use code THEPROOF for up to 35% off your first order at livemomentous.com.

Momentous ships to many countries worldwide depending on local import regulations.

WHOOP

Whoop, the most advanced fitness and health wearable available. Your personalised fitness and health coach to recover faster, sleep better, and train smarter. Claim your first month free on join.whoop.com/simon.

Whoop ships to 56+ international markets, including the US, Canada, most of Europe, Australia, New Zealand, UAE, Singapore, and parts of Asia.

Simon Hill, MSc, BSc (Hons)

• Creator of theproof.com
• Host of The Proof with Simon Hill
• Author of The Proof is in the Plants

Subscribe & Connect:

• YouTube
• Apple Podcasts
• Spotify
• Instagram: @simonhill
• Twitter: @theproof
• Facebook: The Proof with Simon Hill